This is the image supplied to us by the Zodiac Killer on the Phillips 66 Mount Diablo map on June 26th 1970. By placing the numbers 0, 3, 6 and 9 around the crosshairs, akin to a clock face, and instructing us that 0 is to be set to Mag. N, the Zodiac Killer is telling us that we have to travel a certain amount of degrees around the clock face from point zero (set to magnetic north, which was 17 degrees in 1970).

The Zodiac Killer realized that the information he provided in the Button letter was insufficient to discover where he was planning to set the bomb. He also realized it was insufficient to solve the 32-Symbol cipher. That is why he placed two crosshairs in his next communication on July 26th 1970. One of the crosshairs contained the radians value, while the other crosshairs contained the inches value. Zodiac wrote:

"P.S. The Mt. Diablo code concerns Radians + # inches along the radians".

It was that simple, all we had to do was place the first crosshairs (shown on the right) over a compass rose. The center of the little black circle with SFPD next to it, landed exactly at 246 degrees, which is 4 radians and magnetic north. That is the answer to the radians value. The target was SFPD.

The second crosshairs had the phrase "P.S. The Mt. Diablo code concerns Radians + # inches along the radians" written over it. Why would the Zodiac Killer place an arrow pointing before the inches value, if he didn't intend for us to place a number here? The answer could only ever be 5 inches, because using the Phillips 66 map scale of 6.4 miles to the inch, only 5 inches falls over San Francisco (4 & 6 inches falls into the sea).
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The target of SFPD was therefore 4 radians and five inches from Mount Diablo. The target (to a 97.5% accuracy) was the Southern Freeway by Ingleside Police Station, explained in greater detail here.

Druzer and I have recently been working on the Mount Diablo map code solution, using the measurements of four radians and five inches supplied by the Little List letter crosshairs. Druzer came up with a solution to the 32-Symbol cipher that satisfied the three repeating ciphertext characters in the code, giving us an estimate of where the Zodiac Killer was threatening to "set his bomb". The target was the Southern Freeway alongside Ingleside Police Station, stated in a previous article as 4.08 radians (4 radians} and 4.84 inches (5 inches) from Mount Diablo, indicating that the Zodiac Killer was rounding off his values and giving us an estimate.

It has been stated on this site and elsewhere, that the 32 character code is unsolvable using conventional cipher techniques without the killer supplying us with a key. There are 29 unique characters within the code, making any solution practically unprovable. The solutions offered by using the 408 and 340 keys have produced less than convincing results, particularly when we consider that this code contains an "anchor" and "omega" symbol, not used in the 408 and 340 ciphers. Attempting to correlate the letters used in the code to written text in both the Button letter (June 26th 1970) and Little List letter (July 26th 1970) also produces negative results. Therefore, it could be argued, that a code containing 29 unique characters must have an alternative meaning, in accompaniment to the code solution of "estimate:four radians and five inches".

The Zodiac Killer gave us an estimate of 4 radians, but the actual figure (shown above) was 4.084 radians. That is, 4.084 multiplied by one radian value (57.3 degrees) to equal 234 degrees. When we add in the magnetic north which Zodiac instructed us to do (17 degrees in 1970), we get 251 degrees and the location of Ingleside Police Station. Could the 32 character code contain the value of 234 degrees, which once set to magnetic north, now identified the exact location of Ingleside Police Station? If we resort to basic numerology where A=1, B=2, C=3 etc, and add up the values of the alphabetical characters in the Zodiac Killer's 32 character code, we arrive at a total of 234 (or 234 degrees). When set to magnetic north, it gives us the value of 251 degrees, which when subtended from the peak of Mount Diablo passes directly over Ingleside Police Station and the Southern Freeway. "The map (set to 17 degrees magnetic north) coupled with the code of 234 will tell you where the bomb is set".

On July 26th 1970, the Zodiac Killer mailed the Little List letter with the important clues to the Mount Diablo mystery, stating "PS. The Mt. Diablo Code concerns Radians & # inches along the radians". The answer would be about radians and inches. With the northern section of the map crosshairs positioned at zero and to be set to magnetic north, the Zodiac Killer gave us the value of 4 radians and magnetic north (246 degrees) by the placement of the bold, black circle within the first crosshairs on the Little List letter.

The target was the San Francisco Police Department at Ingleside (SFPD). The second set of crosshairs on the Little List letter contained the hashtag (number sign) in the phrase above, with an arrow placed underneath, beckoning us to insert a number before inches. Only 4 radians and magnetic north, coupled with 5 inches could ever fall over San Francisco, constrained by its land mass. No other values can meet the requirement of targetting SFPD. To an overall accuracy in excess of 98%, the location of the bomb was to be set on the embankment of the Southern Freeway just 274 feet from Ingleside Police Station. For the full story, read The Answer to the Mount Diablo Code.

My solution to the 32-Symbol code in the above article did not marry up the ciphertext to the plaintext adequately, however, Druzer, an invaluable contributor to both Zodiac Killer forums, supplied a solution that married up the three repeating ciphertext characters with corresponding plaintext characters. His solution took "PS. The Mt. Diablo Code concerns Radians & # inches along the radians". into "four radians and five inches" that satisfied the requirement of the Zodiac Killer's Mount Diablo code. This would ultimately provide us with 24 of the plaintext characters for the solution, leaving us 8 ciphertext characters to decode. Druzer came up with the answer, but how was this achieved?     

The problem that materialized, was where to place "four radians and five inches" within the 32-Symbol array. We needed an entry point. The clue had to exist within the ciphertext characters themselves. Two of the most notable ciphertext characters were the Anchor and Omega symbols (the latter of which had never been used before), so possibly it was this symbol that held the key of where to insert "four radians and five inches".

The Omega symbol can be written two ways (shown on the left), with a quick search on Wikipedia revealing information on the radian per second. The radian per second (symbol: rad⋅s−1 or rad/s) is the SI unit of angular velocity, commonly denoted by the Greek letter ω (omega). The radian per second is also the SI unit of angular frequency. The radian per second is defined as the change in the orientation of an object, in radians, every second. 

Using this as the entry point in our ciphertext characters, the word "radians" was placed at the beginning of the Omega sign in the code, hoping that the 24 plaintext characters of "four radians and five inches" would travel to the end of the code. Inserting "four" before "radians", It fell into the code seamlessly (as shown below).

Now we can add in the three plaintext characters represented by O, C and ∆ to the three repeating ciphertext characters in the first section of the code, like so.

Ingleside Police Station is actually 4.08 radians (4 radians} and 4.84 inches (5 inches) from Mount Diablo, so the Zodiac Killer was rounding off his values and giving us an estimate. As can be seen in the above diagram, the word "estimate" fits perfectly into the first eight characters of the code, giving us the final answer to the 32-Symbol code of "estimate: four radians and five inches". The Zodiac Killer was informing us that the answer to the Mount Diablo code of "four radians and five inches" was just an estimate to the location of the bomb at Ingleside Police Station (SFPD). The Merriam-Webster dictionary defines "estimate" as a rough or approximate calculation, which is exactly what it is.

In respect to the Mount Diablo code, the Zodiac Killer gave us two clues to where his bomb was to be set, in the form of two crosshairs on July 26th 1970. The first crosshairs contained a bold, black circle positioned at 4 radians and magnetic north around its circumference. Next to this circle, the Zodiac Killer placed SFPD=0, indicating the target was a San Francisco Police Department. The second crosshairs were overwritten with the wording "P.S. The Mt. Diablo code concerns Radians + # inches along the radians". The hashtag (recognized as a number sign) was positioned above a pointing arrow, beckoning us to insert a number value before inches. The answer is five inches, because this is the only value that falls over San Francisco from Mount Diablo using the map scale of 6.4 miles to the inch. The bomb was to be set alongside Ingleside Police Station, on an embankment bordering the Southern Freeway. For further explanation in simplified form, please visit here, or for more extensive coverage read the article The Answer to the Mount Diablo Code.

Footnote: Ordinarily radians would be measured counter-clockwise, but the Zodiac Killer gave us crosshairs superimposed over Mount Diablo with an arrow pointer set in the north facing position, "to be set to Mag. N". He allocated it a zero position, with a 3, 6 and 9 in the form of a clock face around its circumference. This was to instruct us to travel clockwise around the circumference of the crosshairs in this instance. Which is why it was no fluke that the bold, black circle fell exactly at 4 radians and magnetic north.

The Blast Estimate of Zodiac (Part Two)

It is fairly obvious by now that the Zodiac Killer didn't just pluck Mount Diablo out of a hat for the starting point of his Mount Diablo code in the Button letter on June 26th 1970. He knew the history of Mount Diablo and knew that the peak of Mount Diablo was used for the purpose of land boundaries in the majority of Northern California and Nevada, with the summit used as the "initial point", the north/south meridian and east/west baseline intersection point. However, because of the vastness of California, surveying required three "initial points" of Mount Diablo, Mount Pierce and the San Bernardino Mountain to form grid lines.

The Zodiac Killer knew the prominence of Mount Diablo from an elevation standpoint, but very likely knew some of the history and purpose of Mount Diablo - and why he chose this mountain as his "initial point" for the code of radians and inches to be measured from.

It is true that only a tiny proportion of a population would understand what a radian is, but the conclusion drawn from the Zodiac Killer's use of radians as an angular measurement, that he must have been familiar with them through his profession or hobby, is not necessarily the case. He could easily have read a book, magazine, or newspaper article in the preceding hours, days, weeks or months to mailing the Button letter. While most people will not be knowledgeable to the concept of radians, it takes very little time to familiarize oneself with them. Therefore, the idea of radians being a requirement to his daily life through his work (past or present) is not necessarily the case. It may have been a topic he had recently read and so decided to utilize the measurement of radians in his Mount Diablo code. Despite highlighting this point, it is clear that the Zodiac Killer through his communications with the newspapers, did exhibit good "mental mapping" skills in relation to the environment around him. His compass skills were correct in all instances, whether by use of a map or through an extensive knowledge of the locations he murdered in. 

The Zodiac Killer stated correctly that "the girl was on her right side feet to the west" regarding the murder of Betty Lou Jensen at Lake Herman Road. He was correct in his payphone directions after the attack at Blue Rock Springs, stating "If you will go one mile east...... On Columbus Parkway to the public park, you will find the kids in a brown car". The Zodiac Killer was aware of the Volkswagen Karmann Ghia at Lake Berryessa being north of Park Headquarters. He showed his "cardinal points" awareness  in the November 9th 1969 'Bus Bomb' letter, describing his exit through the park of "The dogs never came with in 2 blocks of me + they were to the west + there was only 2 groups of parking about 10 min apart then the motor cicles went by about 150 ft away going from south to north west". All this, along with the use of radians in the Mount Diablo map pinpointing Ingleside Police Station and the Southern Freeway as his supposed bomb target, should give you pause for thought when the Zodiac Killer identified "Washington St and Maple St" as the location of the Paul Stine murder.   

When you factor in the cryptic directions given in the Pines and Monticello cards, it becomes increasingly likely that the Zodiac Killer had a keen interest in maps, the surroundings in which he lived and worked, along with the hunting grounds he chose for murder. It may suggest that he methodically planned out these attacks well in advance, so as to facilitate the best possible chance of escape. Taking this all into consideration, it now becomes a much more reasonable argument to suggest that the Zodiac Killer may have had prior and extensive knowledge of radians, rather than just a passing whim prior to his mailing of the Button letter on June 26th 1970.

The problem with solving the Zodiac Killer's 32 Symbol cipher and Phillips 66 Map code, is a failure to follow the instructions given by the killer in the June 26th 1970 letter and its follow up on July 26th 1970. The Zodiac Killer stated "The map coupled with this code will tell you where the bomb is set.  You have untill next Fall to dig it up". This tells us that the solution to the 32 symbol cipher will not supply us with the exact position of the supposed bomb. Any solution to this 32 character code pinpointing the exact position of the bomb will be incorrect, because this can only be realized by coupling it with the map. Therefore, the position of the bomb to be set, was a combination of both code and map.

In his following letter he stated "P.S. The Mt. Diablo code concerns Radians + # inches along the radians". This tells you that the code is about radians and inches but not necessarily the entire solution. Any solution to the position of the bomb that doesn't use radians and inches (as implicitly stated by the killer) will be wrong. The phrase "P.S. The Mt. Diablo code concerns Radians + # inches along the radians" would supply the inches value, hence the hashtag before inches, along with the arrow beneath, instructing us to insert a value here. This isn't rocket science - the hashtag is widely recognized as a number sign, so by placing this immediately before the word "inches", the Zodiac Killer is telling us to insert a number before inches. The only way to find a bomb in Northern California using his instructions, is to travel a set amount of radians around his crosshairs, and then subtend a set amount of inches from it. In this case, a number of radians around Mount Diablo and a number of inches from it. Placing a hashtag and arrow before the word "inches", is rather a giveaway that a number value should precede it. Even the map code was 6.4 miles to the inch. Any solution that gives us the answer in degrees or miles is wrong, because "The Mt. Diablo code concerns Radians + # inches along the radians". We need to follow his instructions. This is why any theory of crime scene locations being chosen because they are separated by a radian or near radian value, is wrong also. The whole premise of the June 26th 1970 letter was to discover the location of his bomb, not measure angles between crime scenes or any other object we choose to construct or imagine

The Zodiac Killer gave us crosshairs superimposed over Mount Diablo with an arrow pointer set in the north facing position, "to be set to Mag. N". He allocated it a zero position, with a 3, 6 and 9 in the form of a clock face around its circumference. This was to instruct us to travel clockwise around the circumference of the crosshairs, to be set at 17 degrees (which was the magnetic north value in 1970). We had to travel a set amount of radians around his crosshairs over Mount Diablo, in addition to this value of 17 degrees. So, we are looking for a set amount of inches and a set amount of radians. The Zodiac Killer was incapable of keeping secrets and resisting putting pen to paper, so just one month later he gave us the answer, when the July 26th 1970 letter arrived at the San Francisco Chronicle.          

Never done before or since by the Zodiac Killer, he drew a big fat zero around the circumference of his crosshairs with SFPD alongside it. This represented the San Francisco Police Department. This bold, black circle sat at 246.2 degrees, which is 4 radians and magnetic north. This was the radian component of "The Mt. Diablo code concerns Radians + # inches along the radians". The answer was 4 radians. All we had to do now was find the "inches" value.

The Zodiac Killer mailed virtually every correspondence to the San Francisco Chronicle, describing the makeup of his bomb on November 9th 1969. He followed this up with a diagram of a school bus and photoelectric cells on April 20th 1970, referencing the murder of San Francisco police officer Brian McDonnell on February 16th 1970, who suffered devastating and sadly fatal injuries two months earlier, when a bomb packed with fence staples exploded on an outside ledge of Park Police Station in the Upper Haight neighborhood of San Francisco. The Zodiac wrote about the "blast" he was going to have when he mailed the Dragon card on April 28th 1970. All of these communications directed towards the San Francisco Chronicle indicating he was constructing a bomb, with the SFPD attribution totaling zero adorning many. Therefore, it's pretty obvious that placing SFPD around the circumference of his crosshairs, next to a big fat zero and set to a value of 4 radians and magnetic north (4 X 57.3 + 17), indicates that the target for the bomb is San Francisco - or more specifically - the San Francisco Police Department. When the above crosshairs are set over Mount Diablo, we now have to travel 4 radians and magnetic north from the peak of the mountain. Let us now find the inches value to be inserted into "Radians and # inches along the radians".

We actually don't have to look hard to find the answer. The land mass and geography of San Francisco is such, that only 5 inches can fall over it. Using the map scale of 6.4 miles to the inch, anything less than 5 inches, and anything more than 5 inches, doesn't fall inside San Francisco. Therefore, there is only one answer. The same applies to the radians value. Anything more or less than 4 radians and magnetic north (such as 5 radians and magnetic north, or 3 radians and magnetic north), doesn't fall inside the geography of San Francisco. A bomb threat on San Francisco (hence SFPD=0), can only be 4 radians and magnetic north, and 5 inches along that radian value. The choice of words by the Zodiac Killer when he wrote "Radians and # inches along the radians". were chosen carefully. We were instructed to find "radians", and an amount of "inches" along the amount of "radians" we found. Once we found the radians value, we would travel 5 inches along that radian. The answer to the map was the magnetic north value of 17 degrees, to be coupled with four radians and five inches of the code. The two "coupled" together gave us the full answer. Druzer, an avid Zodiac researcher, came up with a solution to the 32 character code which I believe is correct, when he suggested Estimate: four radians and five inches. This solution not only satisfies the 32 characters, but correlates three plaintext letters to the only three repeating ciphertext characters in the code, thereby providing a perfectly valid key. See The Blast Estimate of Zodiac, The Blast Estimate of Zodiac (Part Two). and The Blast Estimate of Zodiac (Part Three).

The map scale is 6.4 miles to the inch. This gives us a distance of 6.4 multiplied by 5 (inches). Therefore, the bomb was to be set at 4 radians and magnetic north, and 32 miles from the peak of Mount Diablo. The only San Francisco Police Department that comes anywhere close is Ingleside Police Station. This San Francisco Police Department sits at 30.96 miles from the peak of Mount Diablo (4.84 inches). It also sits at 251 degrees from the peak of Mount Diablo (4.08 radians).

The Zodiac Killer gave us a rough guide of 4 radians and magnetic north, and 5 inches (hence the word "estimate"). If he had given us the exact measurement, it would have been 4.08 radians and 4.84 inches, He was clearly giving us an approximate measurement. Since Ingleside Police Station was the only San Francisco Police Department anywhere close to these measurements, it's fairly obvious this was his target. The Zodiac Killer's distance in miles was 96.8% accurate. His angular accuracy in degrees was 98.0%. The Zodiac Killer was very unlikely to have selected a specific target that fell on an exact whole number of radians and inches.   

The Zodiac Killer was targeting Ingleside Police Station for his bomb, but clearly he wasn't going to start digging a hole on the lawn of Ingleside Police Station. The Zodiac Killer also threatened to blow up a school bus on April 20th 1970, in which he drew us a diagram with a steep embankment on the right, with the sun rising to the east. This would suggest we should be looking for a bus route traveling from north to south (where the sun rises to the east in the morning), with a steep embankment to the right of the bus, where the Zodiac Killer can lay his photoelectric cells and conceal his bomb. He also has to access that roadway from a position of anonymity, with his vehicle parked at the top of the embankment in relative seclusion. What are the odds of that location being the exact closest portion of road to Ingleside Police Station, meeting all the criteria above. This would satisfy the drawing on the April 20th 1970 letter and the target of SFPD (Ingleside Police Station). The Zodiac Killer could metaphorically kill two birds with one stone.

So let us travel just 274 feet from Ingleside Police Station to the nearest section of road heading north to south.

Again, what are the chances that the area highlighted by the red rectangle would mimic exactly his bomb diagram of a school bus and embankment, as drawn in the April 20th 1970 letter. Not only that, but this would have been a school bus route in 1970. Children from the northern and eastern areas of San Francisco would use the school bus to reach St Thomas More Catholic School at 50 Thomas More Way. There is even a bus route road sign 38 feet from the proposed location of the bomb (whether it existed in 1970 I don't know). So, let us drop down to the exact position of the red rectangle and take a closer look.

All the Zodiac Killer had to do to access the embankment, was to access the parking lot of the City College of San Francisco and drive to its eastern edge - and at night - in relative anonymity to the police station, dig the bomb into the embankment. It is highly unlikely that the Zodiac Killer ever intended to plant a bomb, but this location fits all the criteria of targeting both a San Francisco Police Department and a school bus at the same time. It achieves his objective of targeting school children for maximum terror, and achieves his objective of "rubbing the pigs nozes in their booboos". The location of the bomb not only matches the diagram from April 20th 1970, but satisfies the criteria of the Mount Diablo map and code to an overall accuracy of 97.5%. The 32 character cipher is also answered. The Zodiac Killer likely had no intention of laying this bomb, but it was the threat that mattered most of all. The Zodiac Killer knew that the clues he provided us with on June 26th 1970 were inadequate in cracking the bomb location and code, so he gave us these additional clues in the Little List letter on July 26th 1970, one month later.

# Radian values are normally measured in a counter-clockwise direction, but the positioning of the bold, black circle at 246 degrees (4 radians and magnetic north), along with the north facing arrow pointer, the addition of the clock face set at zero, and the instructions to "set to Mag. N.", appears to indicate the Zodiac Killer measured his radians from the north position clockwise. In effect, he was multiplying the radian value of 57.3 by a factor of 4, set to magnetic north of 17 degrees (246.2).   

It has been stated on this site and elsewhere, that the 32 character code is unsolvable using conventional cipher techniques without the killer supplying us with a key. There are 29 unique characters within the code, making any solution practically unprovable. The solutions offered by using the 408 and 340 keys have produced less than convincing results, particularly when we consider that this code contains an "anchor" and "omega" symbol, not used in the 408 and 340 ciphers. Attempting to correlate the letters used in the code to written text in both the Button letter (June 26th 1970) and Little List letter (July 26th 1970) also produces negative results. Therefore, it could be argued, that a code containing 29 unique characters must have an alternative meaning, in accompaniment to the code solution of "estimate:four radians and five inches". Here is one possibility. 

The Zodiac Killer gave us an estimate of 4 radians, but the exact figure is 4.084 radians. That is, 4.084 multiplied by one radian value (57.3 degrees) to equal 234 degrees. When we add in the magnetic north which Zodiac instructed us to do (17 degrees in 1970), we get 251 degrees and the precise location of the Southern Freeway embankment and Ingleside Police Station. Could the 32 character code contain the value of 234 degrees, which once set to magnetic north, now identified the exact location of Ingleside Police Station? If we resort to basic numerology where A=1, B=2, C=3 etc, and add up the values of the forward facing alphabetical characters in the Zodiac Killer's 32 character code, we arrive at a total of 234 (or 234 degrees). When set to magnetic north, it gives us the value of 251 degrees, which when subtended from the peak of Mount Diablo passes directly over Ingleside Police Station and the Southern Freeway. 

​    "The map (set to 17 degrees magnetic north) coupled with the code of 234 will tell you where the bomb is set".

On April 20th 1970 the Zodiac Killer mailed a letter to the San Francisco Chronicle with three key components. [1] The Zodiac Killer stated "I hope you do not think that I was the one who wiped out that blue meannie with a bomb at the cop station.  Even though I talked about killing school children with one. It just wouldn't doo to move in on someone else's teritory". The Zodiac Killer was referencing the murder of San Francisco police officer Brian McDonnell on February 16th 1970, who suffered devastating and sadly fatal injuries two months earlier, when a bomb packed with fence staples exploded on an outside ledge of Park Police Station in the Upper Haight neighborhood. He continued [2] "But there is more glory in killing a cop than a cid because a cop can shoot back". [3] The Bay Area murderer also included a bus bomb diagram, with a school bus traveling south in the morning and the sun rising to the east. The bomb was positioned on a steep embankment.

It therefore shouldn't be any surprise that his next letter on June 26th 1970 contained all three of these components in its design: [1] He claimed he had set a bomb by Ingleside Police Station, [2] claimed his "glory" by insinuating his involvement in the shooting death of Officer Richard Radetich and [3] his bus bomb diagram matched perfectly the bomb to be set by Ingleside Police Station. 

In the June 26th 1970 Button letter he stated "The Map coupled with the code will tell you where the bomb is set*. It is clear the bomb was to be set in San Francisco, the target for the majority of his communications and ire toward police. The code provided the inches and radians value, and the map was to provide the magnetic north value of 17 degrees in 1970 (to be set at Mag. N" - magnetic north - from his zero point clockwise). This was plainly evident when he provided the extra two clues in the following Little List letter on July 26th 1970.

The positioning of the bomb had to meet certain criteria. With a high degree of accuracy, Ingleside Police Station was situated 4 radians and magnetic north, and 5 inches from Mount Diablo. Even a line subtended from Mount Diablo passing over the neighborhood of Ingleside in San Francisco, when considered alongside the addition of SFPD=0, should have told us that the target for the bomb was likely the San Francisco Police Department in Ingleside. No other police station in San Francisco comes close to 4 radians and magnetic north, and 5 inches along the radians. The next task was looking for the exact location for the bomb to be buried. It most likely would have been set in the vicinity of the police station, just distant enough not to be observed.
 
The bus bomb diagram in the April 20th 1970 letter (shown above) depicted a school bus traveling from north to south in the morning, next to a steep embankment, with the sun rising to the east. This location is just 230 feet from Ingleside Police Station. School buses traveling from the northern and eastern edge of San Francisco to St.Thomas More Catholic School would travel the Southern Freeway, passing only 210 feet from Ingleside Police Station. From this location the bus would be traveling south in the morning to begin classes for the day, the sun would be rising from the east, and this location has a steep embankment mirroring exactly his bus bomb diagram of April 20th 1970. This portion of the Southern Freeway is flanked by the parking lot at the City College of San Francisco. This parking lot is the ideal location to access the embankment without parking on the freeway.        

Sgt Richard P. Radetich (25) was murdered on June 19th at 5:25 am, gunned down by three shots from a .38 caliber revolver at point blank range through the driver side window of his vehicle while in the process of serving a parking ticket. He was sat in his police car near 643 Waller Street, San Francisco in the Lower Haight District. Numerous magazine and newspaper articles covered his brutal execution and gave a background of the young officer's life. Officer Richard Radetich attended Balboa High School in San Francisco, before attending a criminology course at the City College of San Francisco with the express intention of joining the San Francisco Police Department. His first assignment was at Ingleside Police Station, before transferring to the Accident Investigation Bureau.  

The Zodiac Killer was an avid reader of the newspapers and had previously mentioned the murder of Officer Brian McDonnell on February 16th 1970, killed by a bomb placed on the ledge of Park Police Station. In the June 26th 1970 Button letter, the Zodiac Killer claimed his involvement in the murder of Richard Radetich, while giving us a location for the bomb that bisected Ingleside Police Station and the City College of San Francisco - two of the places Officer Richard Radetich attended prior to his murder, while serving in the Accident Investigation Bureau. Had the Zodiac Killer read about the murder of the young officer, and cynically positioned his claimed bomb on the Mount Diablo map at a location pertinent to Officer Radetich's life. Exactly between Ingleside Police Station and the City College of San Francisco? And the design of the bus bomb diagram was just a fortunate coincidence to this location.

The April 20th 1970 bus bomb diagram was penned two months before the murder of Officer Richard Radetich, so if this location was deliberately earmarked well in advance of his murder, it is unlikely the Zodiac Killer chose it because of the history of the young officer in the newspapers subsequent to June 19th 1970. But it wouldn't rule out the deliberate targeting of an officer connected in some fashion to Ingleside Police Station or an advance knowledge of their history, however implausible this may seem. Whatever the case, the primary focus of Ingleside Police Station and an attack on an officer, because "there is more glory in killing a cop" is a viable one. The location of a proposed bomb on the Southern Freeway by Ingleside Police Station, matches both the Mount Diablo map and code of 4 radians set to magnetic north, and 5 inches along the 4th radian. The location also matches perfectly the bus bomb diagram within the April 20th 1970 letter. These still stand, irrespective of any connection to Officer Richard Radetich, which may have no bearing whatsoever. 

The Ingleside Police District encompasses the area south of Cesar Chavez Street to the San Mateo County line and west from Highway 101 to Faxon Avenue. It is  home to the San Francisco City College campus and many diverse residential neighborhoods including Sherwood Forest, Mt. Davidson, Glen Park-Sunnyside, Diamond Heights, Bernal Heights, Upper Noe, Mission Corridor, the Excelsior and St. Francis Wood, St. Mary's Park, Visitacion Valley, Precita Park, Cayuga, Outer Mission and Holly Park.

THE 340 CIPHER WAS CRACKED ON DECEMBER 3RD 2020 BY DAVE ORANCHAK, SAM BLAKE AND JARL VAN EYCKE, SO THIS EARLIER ARTICLE SHOULD BE VIEWED IN RESPECT TO RECENT DEVELOPMENTS.

The one thing we can confidently state about the Zodiac Killer was his propensity to engage with the newspapers when prompted. This was demonstrated throughout his letter-writing campaign, but particularly evident when he responded to Jack E. Stiltz on August 4th 1969 and Chief of Police Martin Lee on November 9th 1969. This was clearly a tactic of the police to engage the Zodiac Killer in communication rather than murder and hopefully ascertain more knowledge of their nemesis through his wording. This was exemplified by Dr. D.C.B. Marsh on October 22nd 1969, when an article entitled Cipher Expert Dares Zodiac to Tell Name was presented to the Zodiac Killer through the San Francisco Examiner, explicitly aimed at prodding his ego. It was hoped that the murderer of five would take up the challenge rather than shy away from the dare or produce something meaningless in response.

Many people have stated that the 408 Cipher was not the hardest cryptogram to solve, despite the fact that many claiming it was an easy cipher could not have cracked it. Hindsight is a wonderful thing. What the 408 Cipher told us, whether the Zodiac Killer just read a book or manual on cipher-solving, is that he had enough knowledge to comprehend that a code comprising of 13 characters was incapable of supplying a provable solution without a key. In other words, if you cannot prove the origin and voracity of the key, anything you produce will fail to meet a burden of proof. The composition and structure of the article below was likely designed to play on the narcissistic traits of the Zodiac Killer and encourage him, at least in part, to rise to the challenge. Responding to the dare in the San Francisco Examiner with absolutely nothing but 13 meaningless characters and no answer whatsoever, is a rather pointless exercise - and could be construed as a failure on Zodiac's part.

The newspaper article pressed the Zodiac Killer no less than four times, implying to do so would lead to his capture under the guise of dare, truth and honesty. I sincerely doubt anybody expected the Bay Area murderer to supply us his full name in the code, to which he would later supply the key or answer. Therefore, the question is, how could the Zodiac satisfy the challenge without giving us his forename and surname? The simple answer is, he could supply us his initials without any fear it would jeopardize his freedom. The important quote in the article is "Zodiac has not done this, because to tell the complete truth in relation to his name - in cipher code - would lead to his capture". Dr. D.C.B. Marsh must have known that a Zodiac Killer providing something 'in relation to his name', left the door open to the murderer supplying us his initials. Six months later, the Zodiac Killer opened his April 20th 1970 communication with "This is the Zodiac speaking. By the way have you cracked the last cipher I sent you. My name is...." 

The Zodiac Killer knew that a code of 13 was unsolvable, which is why he would eventually give us the answer in a later communication in 1970. The prompt was "Zodiac has not done this, because to tell the complete truth in relation to his name - in cipher code - would lead to his capture". The answer was "This is the Zodiac speaking. By the way have you cracked the last cipher I sent you. My name is Fk, I'm crackproof". In other words, my initials are FK and you can't solve the last cipher I sent you because I'm crackproof - although I've held my end of the bargain by supplying something in relation to my name. The Zodiac Killer satisfies his ego and the challenge by Dr. D.C.B. Marsh and the San Francisco Examiner. The answer was supplied in the October 5th 1970 '13 Hole' Postcard - but would we recognise it when we saw it?

The June 26th 1970 Mount Diablo code and map were no different, except this time the Zodiac Killer supplied us the exact answer to the 32 symbol cipher after only 30 days. The Phillips 66 map contained the Zodiac crosshairs as part of the puzzle, so it wasn't that surprising that the answer came embedded within two crosshairs on the July 26th 1970 'Little List' letter. The first crosshairs with the bold circle supplied the radians, and the second crosshairs with the hashtag and arrow supplied the inches. The only two components required to locate the supposed bomb location.

The end of the Little List Letter read "PS. The Mt. Diablo Code concerns Radians and # inches along the radians". The Z32 was the easiest code to crack because the Zodiac Killer just gave us the answer above - the code concerned "Radians and inches along the radians". Why make it any more complicated than it has to be? A code of 29 unique symbols within a total of 32 characters is simply not solvable without a key - and there is insufficient wording on the 13 Hole Postcard, Halloween Card or Los Angeles Letter written in plain English to formulate any such key. The Z32 is even worse than giving us the English alphabet of 26 letters, replacing M with A, W with B and H with C and saying "now solve it". There is no transposition key present in the remaining three communications from October 5th 1970 to March 13th 1971, so if the Zodiac Killer was to be consistent in his inability to resist revealing his deeds, then the only realistic alternative is he gave us all the answers instead.      

Not only did the Zodiac Killer give us the answer to the 32 character code on a separate line, he capitalized the first "Radians" to effectively tell us this was the beginning of the solution (he didn't capitalize the second "radians", so why the first). You need look no further than the Paul Stine police report to notice that the hashtag symbol is used in conjunction with a number. Why insert a hashtag - and an arrow pointing to the hashtag - if you are not suggesting something should be inserted here?

The symbol # is most commonly known as the number sign, The symbol is described as the "number" character in an 1853 treatise on bookkeeping, and its double meaning is described in a bookkeeping text from 1880. The instruction manual of the Blickensderfer model 5 typewriter (c. 1896) appears to refer to the symbol as the "number mark". Some early-20th-century U.S. sources refer to it as the "number sign", although this could also refer to the numero sign. A 1917 manual distinguishes between two uses of the sign: "number (written before a figure)"; and "pounds (written after a figure)". Mainstream use in the United States is as follows: when it prefixes a number, it is read as "number", as in "a #2 pencil" (indicating "a number-two pencil"). The one exception is with the # key on a phone, which is always referred to as the "pound key" or "pound". Thus instructions to dial an extension such as #77 are always read as "pound seven seven". Wikipedia.

The Zodiac Killer by use of an arrow pointer underneath the hashtag, was telling us to replace the hashtag with a number value. The Mount Diablo map scale was 6.4 miles to the inch, so it is probably unsurprising that the "Mt Diablo code would concern inches". In this instance, I have placed the number 5 into place, giving us the answer to the code of "Radians and 5 inches along the radians" (which is 32 letters in length). The reason for 5 inches is self explanatory, because 4 or 6 inches from Mount Diablo to San Francisco would fall into the sea on the east and west side. The San Francisco element will be covered shortly. The Zodiac Killer also gave us a second set of crosshairs (shown below).

This was the first time the Zodiac Killer had ever placed an accentuated zero within his crosshairs alongside the acronym SFPD. This had to be the second clue to the location of the bomb. The hashtag and arrow signified the value of inches required, so this had to signify the radian value. By some massive stroke of luck (almost beyond belief), the bold, black accentuated circle fell over 246 degrees on a compass rose - which is 4 radians and magnetic north (17 degrees in 1970). Therefore, the target of his bomb must have been 4 radians and magnetic north, and 5 inches along the radians. 

All Zodiac's bomb threats were focused towards the San Francisco Chronicle and San Francisco Police Department, so placing this bomb location alongside the acronym SFPD should tell us that the threat was most likely focused toward a police station. By another massive stroke of luck, when we travel 4 radians and 5 inches from Mount Diablo, the target area for the bomb lies right by Ingleside Police Station. Allowing for a degree of flexibility of less than 1%, by the Zodiac Killer rounding off his radians and inches, along with the black circle diameter, no other San Francisco police station comes close. However, we need to find a location where a school bus would be traveling from north to south (with the sun to the east), that has an embankment on the right side (as displayed on the April 20th 1970 bomb diagram), with easy and covert access to that embankment, and within a few hundred feet from Ingleside Police Station. The Zodiac Killer certainly wouldn't have wanted to attract attention by parking on the road itself, but by accessing the incline from a secondary location - likely at the top of the embankment - he could achieve this task in relative anonymity. Fortunately for us, that location sits only 230 feet from Ingleside Police Station. The perfect location for the Zodiac Killer to target a school bus and thumb his nose at the San Francisco Police Department, with covert access to the top of the embankment via the car park of San Francisco City College.     

The 32 character code wasn't the complete solution, because the Zodiac Killer explicitly stated "the map coupled with the code will tell you where the bomb is set". The code contained the inches by way of "Radians and 5 inches along the radians", to be coupled with the map which contained the 4 radians and Mag. N (246.2 degrees). A bomb set here would have had maximum impact, striking a school bus as Zodiac had promised, but more importantly, right under the noses of the San Francisco Police Department for acute embarrassment.        

In addition to the Fk I'm crackproof clue, the 13 Hole Postcard was punched in the style of a 'Dick Tracy' code with a "red crucifix decoder". What are the chances that if we arrange the 13 holes into the shape of a cross and place them over the midsection of the 340 cipher both horizontally and vertically, they would reveal the wording "paradice" and "slaves"? Then, what are the chances that the Zodiac Killer would write "paradice" and "slaves" in his next communication in a cross formation on the card, accompanied by "sorry no cipher" in a cross formation on the inside of the Halloween Card envelope? - totaling three cross formations - but supposedly, all created for absolutely no reason whatsoever in just two communications. Isn't it more believable they were created for purpose. The Zodiac Killer could easily have written "sorry no cipher" just the once, but deliberately fashioned it this way to tell us that the 340 character cipher was not a cipher after all. It was simply a design of "paradice" and "slaves" as exhibited by the Halloween Card. Throw in a few bigrams, pivots and 'corrected sixth line', and hopefully it will look convincing. 

All these clues from the back end of the Little List Letter to the Halloween Card giving us the literal answer to the Z340, Z32 and Z13 in "paradice" and "slaves", "Radians and 5 inches along the radians".and "Fk, I'm crackproof".  The following observations will go into a little more detail on the Z13 code.

On January 29th 1970, the Yellow Cab Company put up a thousand dollar reward for any information leading to the arrest of the Zodiac Killer. In addition, the Teamsters Union which represents the Yellow Cab Company were reported in the San Francisco Chronicle to be considering offering a further reward on February 8th 1970 in the case of Paul Stine and Charles Jarman (another taxicab murder victim). The April 20th 1970 letter gave us the code and was immediately followed by "I am mildly cerous as to how much money you have on my head now". The October 5th 1970 postcard gave us the possible solution of "Fk, I'm crackproof" and was immediately followed by "What is the price tag now". These are the only two communications in which the Zodiac Killer asked the police the price of his capture. These two communications not only had a code and an answer that fitted the code, but both were followed by the exact same question. When the Zodiac Killer was designing his 13 Hole Postcard, it is very likely he had at his disposal a copy of his original April 20th 1970 letter, or the San Francisco Chronicle newspaper cutting below, to which he was now supplying the answer. This may have been the trigger that influenced him to repeat the phrase "how much money you have on my head now" into the very similar "What is the price tag now". The Zodiac Killer, in essence, had inadvertently bound both communications together through phraseology, as well as code and solution.   

The Zodiac Killer introduction would now give us his name (albeit his initials) in absence of his full name. It would also read fluently as a sentence, as follows: "This is the Zodiac speaking. By the way have you cracked the last cipher I sent you? My name is Fk, I'm crackproof". Nobody realistically believed he was going to supply his full name, but this way he satisfies the promise in a restricted format. Two communications mailed nearly six months apart, with a solution that satisfies the code, as well as a satisfactory introduction to the code - and both followed by the same question.    

The three 8's (representing Jesus Christ in gematria), along with the number 8 which symbolizes a new beginning, actually begins each element of the phrase Fk I'm crackproof. In addition, when we begin the phrase on the first 8, it fits perfectly around the existing K and M already present in the code and thereby creating a cyclical format, where the code ends and begins with the same letter. The Little List Letter provided the solution to the Button Letter and Mount Diablo code that preceded it. His next communication, the 13 Hole Postcard, provided the solution to the 13 Symbol Cipher before that, and finally the Halloween Card provided the solution to the 340 cipher. Three chronological solves to the three previous ciphers - and the only thing we had to add was the number "5", for which he inserted the hashtag and arrow. Why look for convoluted and excessively complicated solutions to these ciphers, when the Zodiac Killer gave us all the answers literally word for word.

This isn't a case of dragging wording from the entire Zodiac collection of cards and letters, but using just the two crosshairs of the Little List Letter, followed by the 13 Hole Postcard and Halloween Card. The bold, black circle and "PS. The Mt. Diablo Code concerns Radians and # inches along the radians" to answer the Z32. The 13 holes, red cross, "paradice" and "slaves", and "sorry no cipher" to answer the Z340. And finally, "Fk, I'm crackproof" to give us a shorthanded version of his name, while still retaining his anonymity. Three answers in just three months. The alternative is that the codes are genuine, the designs on the 13 Hole Postcard and Halloween Card are devoid of any purposeful meaning, and the big-headed, braggart called Zodiac, kept his lips 'butoned' for however many years afterwards.

The Zodiac Killer gave us the answers to his six unsolved ciphers by March 13th 1971 without ambiguity, but effectively gave us all the answers by October 27th 1970. The Zodiac gave us the answer to the Mount Diablo code (32 symbol Cipher} in the Little List Letter on July 26th 1970. In fact, he gave us the answer word for word, in the form of Radians and 5 inches along the radians (all we had to do was add the number 5 where he placed the arrow and hashtag}. The 13 Hole Postcard on October 5th 1970 gave us the answer to the 13 Symbol Cipher word for word, in the form of Fk I'm crackproof. The Halloween Card on October 27th 1970 gave us the answer to the 340 Cipher word for word, in the form of Paradice and Slaves. No mathematics was required and no manipulation was needed - all we had to do was use the three phrases that Zodiac provided us with in three consecutive communications, to answer the three previously unsolved ciphers. But that wasn't all. The Zodiac gave us the answer to both the Fairfield Letter codes of December 7th and 16th of 1969, again word for word using the Halloween Card. The 18 unsolved characters in the 408 cipher he again gave us the solution word for word, using the trinity of communications on July 31st 1969 and following letter on August 4th 1969, when he revealed his pseudonym to the world. However, there is even more.

The Zodiac Killer's 408 Cipher was effectively a written message that he enciphered into characters. When you take a look at the decoded message, it isn't structured and organized - because one line or row bleeds into the following. The Zodiac Killer didn't contain his words within the confines of one row. For example, when he opened the cipher with "I like killing people", the letter E is positioned at the beginning of the second row. This randomness is not displayed in the answers to his remaining six unsolved portions of code. The answer to the 18 unsolved characters, the 340 Cipher, the two Fairfield letters, the 13 Symbol Cipher and the 32 Symbol Cipher are all organized and deliberately structured, where every single solution and word is contained within each line - and do not leak from one row to another. Let us take a look at the 13 Symbol Cipher that exhibits symmetry within its design.

When the Zodiac's solution or answer to the 13 Symbol Cipher was inserted into the code above, it showed an organized and structured pattern without a word bleeding from one end of the cipher to the other. The Zodiac Killer gave us the cyclical solution of Fk I'm crackproof on October 5th 1970, and followed this up with the line "This is the Zodiac speaking Like I have allways said, I am crack proof" on March 13th 1971. But in the Los Angeles Letter you will notice he separates "crackproof" to "crack proof", exactly how it is found in the 13 Symbol Cipher. It does not bleed from the end of the cipher to the start.

The first 8 begins FK. The second 8 begins IM. The third 8 begins CRACKPROOF. But CRACK and PROOF are separated, without either word being fragmented. The FK and IM also fit nicely around the existing K and M in the cipher. The cipher solution maintains an organized and symmetrical appearance. The introduction on the April 20th 1970 letter now read "This is the Zodiac speaking. By the way have you cracked the last cipher I sent you? My name is Fk, I'm crackproof". He was leading us into the belief these were his initials.

The Paradice and Slaves configuration from the Halloween Card to the 340 Cipher also exhibited form, with Paradice exactly bisecting the columns of the 340 Cipher, and Slaves exactly bisecting the rows of the 340 Cipher in a 17 X 17 pattern. Each word contained within a row or column. The Halloween Card envelope providing us with "sorry no cipher" in a cross formation, not only telling us that the 340 wasn't a standard cipher, but the design of the 340 was to be found in a cross formation.

The 32 Symbol Cipher also adhered to a solution where no word bled from one row to another. The 32 Symbol Cipher contained two rows of 17 and 15 characters - obviously created this way for a purpose. When we discovered that the number 5 was to be inserted into the cipher using the arrow and hashtag, the answer of Radians and 5 inches along the radians again fell perfectly into the 32 Symbol Cipher with no word extending from one line to another. You will notice that when the Zodiac Killer provided us with the answer in the July 26th 1970 Little List Letter, he self-contained the answer on a separate line, with the first Radians beginning with a capital letter. This was the beginning of the code solution.

"PS. The Mt. Diablo Code concerns Radians and # inches along the radians" was in fact Radians and 5 inches along the radians. When this is placed into the 32 Symbol Cipher, you will notice that once again it retains separation, with "inches" ending line one, and "along" beginning line two. Each word is contained within the line. This organization and structure flies in the face of the solved portion of the 408 Cipher and implies a deliberate and calculated design. But we need to take it even further.

Explained in greater detail in the article The Answer to the Z38 Code, the structure of the Zodiac 38 character cipher was pointed out. The code below has been structured with different character counts on each line (unlike the 408 and 340 ciphers), but is instead arranged in a formation of 12 characters on line one, 7 characters on line two, 5 characters on line three, 6 characters on line four and 8 characters on line five. This may suggest that the words are contained separately on each line, without running from one line to another. We would expect Slaves and Paradice to be grouped together - and the last two lines satisfy this character count of 6 and 8. We then have three lines remaining of 12, 7 and 5 characters. By Gun satisfies the 5 characters, By Knife satisfies the 7 characters, and By Fire, By Rope satisfies the 12 characters. This forms the basis of the completed 38 character code solution, mimicking the second Fairfield Letter design and the exact wording on the Halloween Card configuration. Furthermore, no word extends from one line to another, exactly as displayed in the above codes.

For anybody believing that the two Fairfield letters mailed on December 7th 1969 and December 16th 1969 were just a hoaxer, unrelated to Zodiac, then they have to explain, not only what purpose they served, but how the 38 character code manufactured by a lazy imbecile, incapable of even recreating a credible Zodiac Killer communication, just so happened to design five lines of 12, 7, 5, 6 and 8 characters, which could by sheer accident allow by fire, by rope, by knife, by gun, slaves and paradice to fall nicely onto each line. Ten words, self-contained on each line, which just happened to correlate with the October 27th 1970 Halloween card, ten months in the making. Not to mention, that by fire, by rope, by knife, by gun, slaves and paradice can be found in the "word search" 340 cipher just 29 days prior, in exactly the same design as the Halloween card.

Any doubts that the December 7th 1969 coding was a hint to the solution of the 340 cipher, should have been lessened by the inclusion of many repeating sequences of characters from the November 8th 1969 offering. The above configuration in the 340 cipher will probably be described as accidental by eminent codebreakers. However, if the December 7th 1969 author was just an ignorant charlaton, bereft of the solution to the 340 cipher, who just slapped a quick and meaningless 38 character code together, then it has to be purely by chance once again, that he managed to fortuitously create a code of 38 characters that mimicked the exact character count of by fire, by rope, by knife, by gun, slaves and paradice, present in two other cryptic communications mailed by the Zodiac Killer. Not only was this extremely lucky, but the clown impersonator of Zodiac, would for a futher time, just happen to create another cryptic addition on December 16th 1969 that mimicked the Zodiac designs in the 340 cipher and Halloween card.  

The Zodiac Killer was rather quite polite on November 8th 1969, when he cordially requested "could you print this new cipher in your frunt page?" However, after 38 days his patience was running thin, aghast at the inability of code breakers to pry open his simplistic cipher. In fact, he was starting to get bloody pissed off with authorities, demanding "you better print" in his December 16th 1969 letter (see right). Underneath his demand was yet another clue to his 340 cipher, and a design that again mimicked the yet to be mailed Halloween card.

The Tim Holt comic book connection unearthed by Tahoe27 (displayed in the Halloween card), not only contained the four phrases of by gun, by knife, by rope and by fire in each quadrant, but they were preceded by the word "death" in the comic itself. Exactly as depicted in the configuration on the right.
There are five characters, followed by four crosshairs placed around a larger crossed circle. This hoaxer was certainly having a bit of luck, creating 38 characters to mimic the Halloween card words of paradice, slaves, by gun, by knife, by rope and by fire, but also mimicking the design - including each mode of murder by the possible 5-letter introduction of "death", found on the wheel of the Tim Holt comic book.

The luck doesn't end there mind. The author of the December 7th 1969 letter wrote the words "I just need help". The phrase "please help me" would appear thrice in the authenticated Melvin Belli letter on December 20th 1969, despite the fact neither of the two Fairfield letters were ever published in the newspapers. Damn, this hoaxer is seemingly getting a lot of things correct, even thirteen days and ten months in advance.

So far (including the Tim Holt comic book unearthed by Tahoe27), every single solution or answer to the ciphers can be achieved using the exact words employed by Zodiac from three consecutive communications spanning July 26th 1970 to October 27th 1970. [1] Radians and 5 inches along the radians [2] Fk I'm crackproof [3] Paradise and Slaves, and [4] By Fire, By Gun, By Rope, By Knife, Paradice and Slaves. And none extend or bleed into another line, or from end to beginning in the 13 Symbol Cipher. That is five ciphers down with one to go. 

The Zodiac Killer claimed that his 408 Cipher contained his identity or pseudonym. What was important to the Bay Area murderer was the structure exhibited by all the above codes. The characters he used were of no particular significance, because they weren't designed to be solved without future Zodiac input. This input came towards the end of his letter writing campaign, when he supplied us all the answers in just three consecutive communications. He was effectively wrapping up business. There was no way a man with such an inflated ego and inability to resist writing to the newspapers, could keep the secret to his ciphers for upwards of five decades. The answer to the 408 Cipher was given to us in just four days, contained in the trinity of July 31st 1969 letters and the August 4th 1969 'Debut of Zodiac' Letter. He claimed his identity was in the 408 cipher - and we know his identity was "Zodiac" because he gave us his pseudonym. All we then had to do, was fit Zodiac around the declaration of who he was. 

Initially, the Zodiac Killer had intended to leave 12 characters at the base of the 408 Cipher, but his accidental omission of the word "people" when he encoded his message, inadvertently left him with 18 unsolved characters. However, this was of no consequence - it was an easy adjustment. You will notice again, that the unsolved 18 characters are split into an ungainly 1 and 17 configuration. If we are to hold true to single words not bleeding from one line to another, then the single character must stand for I or A. We know that the Zodiac Killer was an egotist, beginning the 408 Cipher with "I like killing people because it is so much fun". He also began two of the July 31st letters with "I am the killer". So it wouldn't be any great leap of faith to believe that the isolated singular character on line 23 was "I". Coupling the "Zodiac" with "I am the killer" to produce "I am the Zodiac Killer" satisfies his declaration of identity and the 18 characters at the base of the 408 Cipher. We again have used only the words written by the Zodiac Killer - and no word extends from one line to another. The third of code containing his identity was mailed to the San Francisco Chronicle, which is why he began that introduction with "This is the murderer". He was reserving "I am the Zodiac Killer" for the base of the 408 Cipher.  

We now have six unsolved portions of code answered, using only the words written by the Zodiac Killer in a total of four communications. Every single answer was organized and structured to remain within each row, line and column with no manipulation whatsoever. We can wait another 50 years for these codes to be "solved" - or believe they were all answered by October 27th 1970 from the pen of the Zodiac Killer.

The Zodiac Killer gave us the answers to his six unsolved ciphers by March 13th 1971 without ambiguity, but effectively gave us all the answers by October 27th 1970. It is important to read Three Months After the Mount Diablo Code to understand all of the following, but I shall give a very brief recap. The Zodiac gave us the answer to the Mount Diablo code (32 symbol Cipher} in the Little List Letter on July 26th 1970. In fact, he gave us the answer word for word, in the form of Radians and 5 inches along the radians (all we had to do was add the number 5 where he placed the arrow and hashtag}. The 13 Hole Postcard on October 5th 1970 gave us the answer to the 13 Symbol Cipher word for word, in the form of Fk I'm crackproof. The Halloween Card on October 27th 1970 gave us the answer to the 340 Cipher word for word, in the form of Paradice and Slaves. No mathematics was required and no manipulation was needed - all we had to do, was use the three phrases that Zodiac provided us with in three consecutive communications, to answer the three previously unsolved ciphers. But that wasn't all. The Zodiac gave us the answer to both the Fairfield Letter codes of December 7th and 16th of 1969, again word for word using the Halloween Card. The 18 unsolved characters in the 408 cipher he again gave us the solution word for word, using the trinity of communications on July 31st 1969 and following letter on August 4th 1969, when he revealed his pseudonym to the world. However, there is even more.

The Zodiac Killer's 408 Cipher was effectively a written message that he enciphered into characters. When you take a look at the decoded message, it isn't structured and organized - because one line or row bleeds into the following. The Zodiac Killer didn't contain his words within the confines of one row. For example, when he opened the cipher with "I like killing people", the letter E is positioned at the beginning of the second row. This randomness is not displayed in the answers to his remaining six unsolved portions of code. The answer to the 18 unsolved characters, the 340 Cipher, the two Fairfield letters, the 13 Symbol Cipher and the 32 Symbol Cipher are all organized and deliberately structured, where every single solution and word is contained within each line - and does not leak from one row to another. Let us take a look at the 13 Symbol Cipher that exhibits symmetry within its design.             

I don't have to explain the above, because its structure and symmetry is there for all to see. The Zodiac Killer had already responded to prompts by Vallejo Police Chief Jack Stiltz to send more details to prove the letter writer and killer were one and the same. The more the Zodiac Killer wrote, not only lessened his time for killing, but may have provided additional clues to detectives regarding his identity. This tactic was likely adopted by Professor D.C.B. Marsh in the October 22nd 1969 San Francisco Examiner newspaper article by Will Stevens, which laid down a challenge to the Zodiac Killer to reveal his name. The newspaper stated Dr Marsh told the Examiner today: "The killer wouldn't dare, as he claimed in letters to the newspapers, to reveal his name in the cipher to established cryptogram experts. He knows, to quote Edgar Allen Poe, that any cipher created by man can be solved by man. Zodiac has not told the truth in his cipher messages to the Examiner, the Chronicle and the Vallejo Times-Herald. Zodiac has not done this, because to tell the complete truth in relation to his name -in cipher code - would lead to his capture. I invite Zodiac to send The American Cryptogram Association a cipher code - however complicated - which will truly and honestly include his name".

The above invitation by Dr. Marsh, quoting Edgar Allen Poe, was met with the 13 Symbol Cipher that mirrored a code used in Poe's A Few Words on Secret Writing. The alphabet being split A to M, and N to Z. The 13 Symbol Cipher began with A and ended with M. So it was logical to place the alphabet alongside the 13 Symbol Cipher and see if any patterns emerged by counting the numerical difference between corresponding characters. This resulted.

I don't want to labor the point again, so for a full explanation please visit the article Embedded Symmetry  Suffice to say, that when the Zodiac's solution or answer to the 13 Symbol Cipher was inserted into the code above, it showed an organized and structured pattern without a word bleeding from one end of the cipher to the other. The Zodiac Killer gave us the cyclical solution of Fk I'm crackproof on October 5th 1970, and followed this up with the line "This is the Zodiac speaking Like I have allways said, I am crack proof" on March 13th 1971. But in the Los Angeles Letter you will notice he separates "crackproof" to "crack proof", exactly how it is found in the 13 Symbol Cipher. It does not bleed from the end of the cipher to the start.

The first 8 begins FK. The second 8 begins IM. The third 8 begins CRACKPROOF. But CRACK and PROOF are separated, without either word being fragmented. The FK and IM also fit nicely around the existing K and M in the cipher. The cipher solution maintains an organized and symmetrical appearance. The introduction on the April 20th 1970 letter now read "This is the Zodiac speaking. By the way have you cracked the last cipher I sent you? My name is Fk, I'm crackproof". He was leading us into the belief these were his initials.

The Paradice and Slaves configuration from the Halloween Card to the 340 Cipher also exhibited form, with Paradice exactly bisecting the columns of the 340 Cipher, and Slaves exactly bisecting the rows of the 340 Cipher in a 17 X 17 pattern. Each word contained within a row or column. The Halloween Card envelope providing us with "sorry no cipher" in a cross formation, not only telling us that the 340 wasn't a standard cipher, but the design of the 340 was to be found in a cross formation.

The 32 Symbol Cipher also adhered to a solution where no word bled from one row to another. The 32 Symbol Cipher contained two rows of 17 and 15 characters - obviously created this way for a purpose. When we discovered that the number 5 was to be inserted into the cipher using the arrow and hashtag, the answer of Radians and 5 inches along the radians again fell perfectly into the 32 Symbol Cipher with no word extending from one line to another. You will notice that when the Zodiac Killer provided us with the answer in the July 26th 1970 Little List Letter, he self-contained the answer on a separate line, with the first Radians beginning with a capital letter. This was the beginning of the code solution.

"PS. The Mt. Diablo Code concerns Radians and # inches along the radians" was in fact Radians and 5 inches along the radians. When this is placed into the 32 Symbol Cipher, you will notice that once again it retains separation, with "inches" ending line one, and "along" beginning line two. Each word is contained within the line. This organization and structure flies in the face of the solved portion of the 408 Cipher and implies a deliberate and calculated design. But we need to take it even further.

Explained in greater detail in the article The Answer to the Z38 Code, the structure of the Zodiac 38 character cipher was pointed out. The code below has been structured with different character counts on each line (unlike the 408 and 340 ciphers), but is instead arranged in a formation of 12 characters on line one, 7 characters on line two, 5 characters on line three, 6 characters on line four and 8 characters on line five. This may suggest that the words are contained separately on each line, without running from one line to another. We would expect Slaves and Paradice to be grouped together - and the last two lines satisfy this character count of 6 and 8. We then have three lines remaining of 12, 7 and 5 characters. By Gun satisfies the 5 characters, By Knife satisfies the 7 characters, and By Fire, By Rope satisfies the 12 characters. This forms the basis of the completed 38 character code solution, mimicking the second Fairfield Letter design and the exact wording on the Halloween Card configuration. Furthermore, no word extends from one line to another, exactly as displayed in the above codes.

So far (including the Tim Holt comic book unearthed by Tahoe27), every single solution or answer to the ciphers can be achieved using the exact words employed by Zodiac from three consecutive communications spanning July 26th 1970 to October 27th 1970. [1] Radians and 5 inches along the radians [2] Fk I'm crackproof [3] Paradise and Slaves, and [4] By Fire, By Gun, By Rope, By Knife, Paradice and Slaves. And none extend or bleed into another line, or from end to beginning in the 13 Symbol Cipher. That is five ciphers down with one to go. 

The Zodiac Killer claimed that his 408 Cipher contained his identity or pseudonym. What was important to the Bay Area murderer was the structure exhibited by all the above codes. The characters he used were of no particular significance, because they weren't designed to be solved without future Zodiac input. This input came towards the end of his letter writing campaign, when he supplied us all the answers in just three consecutive communications. He was effectively wrapping up business. There was no way a man with such an inflated ego and inability to resist writing to the newspapers, could keep the secret to his ciphers for upwards of five decades. The answer to the 408 Cipher was given to us in just four days, contained in the trinity of July 31st 1969 letters and the August 4th 1969 'Debut of Zodiac' Letter. He claimed his identity was in the 408 cipher - and we know his identity was "Zodiac" because he gave us his pseudonym. All we then had to do, was fit Zodiac around the declaration of who he was. 

Initially, the Zodiac Killer had intended to leave 12 characters at the base of the 408 Cipher, but his accidental omission of the word "people" when he encoded his message, inadvertently left him with 18 unsolved characters. However, this was of no consequence - it was an easy adjustment. You will notice again, that the unsolved 18 characters are split into an ungainly 1 and 17 configuration. If we are to hold true to single words not bleeding from one line to another, then the single character must stand for I or A. We know that the Zodiac Killer was an egotist, beginning the 408 Cipher with "I like killing people because it is so much fun". He also began two of the July 31st letters with "I am the killer". So it wouldn't be any great leap of faith to believe that the isolated singular character on line 23 was "I". Coupling the "Zodiac" with "I am the killer" to produce "I am the Zodiac Killer" satisfies his declaration of identity and the 18 characters at the base of the 408 Cipher. We again have used only the words written by the Zodiac Killer - and no word extends from one line to another. The third of code containing his identity was mailed to the San Francisco Chronicle, which is why he began that introduction with "This is the murderer". He was reserving "I am the Zodiac Killer" for the base of the 408 Cipher.  

We now have six unsolved portions of code answered, using only the words written by the Zodiac Killer in a total of four communications. Every single answer was organized and structured to remain within each row, line and column with no manipulation whatsoever. We can wait another 50 years for these codes to be "solved" - or believe they were all answered by October 27th 1970 from the pen of the Zodiac Killer.

THE 340 CIPHER WAS CRACKED ON DECEMBER 3RD 2020 BY DAVE ORANCHAK, SAM BLAKE AND JARL VAN EYCKE, SO THIS EARLIER ARTICLE SHOULD BE VIEWED IN RESPECT TO RECENT DEVELOPMENTS.

The following article will coalesce several pieces of work from 2019 into one cogent story regarding a handful of communications mailed by the Zodiac Killer in 1970. For some, the following will be repetitive, for which I apologize. It will hopefully make the case that the Zodiac Killer was winding down his operations and ultimately revealing the answers to his Z340, Z32 and Z13 ciphers and codes, to which he knew were practically unsolvable without such a prompt. The Zodiac Killer was a narcissistic braggart, who boasted of his exploits and threatened all and sundry with the possibility of more murders and mayhem if his demands were not met, including the claim he had killed far more than could be accounted for. If we applied the same model to his ciphers and codes, we would have expected him to be unable to resist giving us the answers - or at the very least - some clues to break open his puzzles. The notion of a killer keeping deathly silent on the solutions to his codes for up to 50 years, runs contrary to everything we know about the Bay Area murderer during his brief but deadly reign. That is why I don't believe he did.

The story begins with the final thing he wrote on the July 26th 1970 Little List Letter, and finishes just two communications later with the October 27th 1970 Halloween Card. All the answers to his codes were contained in just three short months. The end of the Little List Letter read "PS. The Mt. Diablo Code concerns Radians and # inches along the radians". The Z32 was the easiest code to crack because the Zodiac Killer just gave us the answer above - the code concerned "Radians and inches along the radians". Why make it any more complicated than it has to be? A code of 29 unique symbols within a total of 32 characters is simply not solvable without a key - and there is insufficient wording on the 13 Hole Postcard, Halloween Card or Los Angeles Letter written in plain English to formulate any such key. The Z32 is even worse than giving us the English alphabet of 26 letters, replacing M with A, W with B and H with C and saying "now solve it". There is no transposition key present in the remaining three communications from October 5th 1970 to March 13th 1971, so if the Zodiac Killer was to be consistent in his inability to resist revealing his deeds, then the only realistic alternative is he gave us all the answers instead.

Not only did the Zodiac Killer give us the answer to the 32 character code on a separate line, he capitalized the first "Radians" to effectively tell us this was the beginning of the solution (he didn't capitalize the second "radians", so why the first). You need look no further than the Paul Stine police report to notice that the hashtag symbol is used in conjunction with a number. The Zodiac Killer by use of an arrow pointer underneath the hashtag, was telling us to replace the hashtag with a number value. The Mount Diablo map scale was 6.4 miles to the inch, so it is probably unsurprising that the "Mt Diablo code would concern inches". In this instance, I have placed the number 5 into place, giving us the answer to the code of "Radians and 5 inches along the radians" (which is 32 letters in length). The reason for 5 inches is self explanatory, because 4 or 6 inches from Mount Diablo to San Francisco would fall into the sea on the east and west side. The San Francisco element will be covered shortly. The Zodiac Killer also gave us a second set of crosshairs (shown below).

This was the first time the Zodiac Killer had ever placed an accentuated zero within his crosshairs alongside the acronym SFPD. This had to be the second clue to the location of the bomb. The hashtag and arrow signified the value of inches required, so this had to signify the radian value. By some massive stroke of luck (almost beyond belief), the bold, black accentuated circle fell over 246 degrees on a compass rose - which is 4 radians and magnetic north (17 degrees in 1970). Therefore, the target of his bomb must have been 4 radians and magnetic north, and 5 inches along the radians. 

All Zodiac's bomb threats were focused towards the San Francisco Chronicle and San Francisco Police Department, so placing this bomb location alongside the acronym SFPD should tell us that the threat was most likely focused toward a police station. By another massive stroke of luck, when we travel 4 radians and 5 inches from Mount Diablo, the target area for the bomb lies right by Ingleside Police Station. Allowing for a degree of flexibility of less than 1%, by the Zodiac Killer rounding off his radians and inches, along with the black circle diameter, no other San Francisco police station comes close. However, we need to find a location where a school bus would be traveling from north to south (with the sun to the east), that has an embankment on the right side (as displayed on the April 20th 1970 bomb diagram), with easy and covert access to that embankment, and within a few hundred feet from Ingleside Police Station. The Zodiac Killer certainly wouldn't have wanted to attract attention by parking on the road itself, but by accessing the incline from a secondary location - likely at the top of the embankment - he could achieve this task in relative anonymity. Fortunately for us, that location sits only 230 feet from Ingleside Police Station. The perfect location for the Zodiac Killer to target a school bus and thumb his nose at the San Francisco Police Department, with covert access to the top of the embankment via the car park of San Francisco City College.             

Then came the 13 Hole Postcard punched in the style of a 'Dick Tracy' code with a "red crucifix decoder". What are the chances that if we arranged the 13 holes into the shape of a cross and place it over the midsection of the 340 cipher both horizontally and vertically, it would reveal the wording "paradice" and "slaves"? Then, what are the chances that the Zodiac Killer would write "paradice" and "slaves" in his next communication in a cross formation on the card, accompanied by "sorry no cipher" in a cross formation on the inside of the Halloween Card envelope? - totaling three cross formations - but supposedly, all created for absolutely no reason whatsoever in just two communications. Isn't it more believable they were created for purpose. The Zodiac Killer could easily have written "sorry no cipher" just the once, but deliberately fashioned it this way to tell us that the 340 character cipher was not a cipher after all. It was simply a design of "paradice" and "slaves" as exhibited by the Halloween Card. Throw in a few bigrams, pivots and 'corrected sixth line', and hopefully it will look convincing. 

All these clues from the back end of the Little List Letter to the Halloween Card giving us the literal answer to both the Z340 and Z32 in "paradice" and "slaves", and "Radians and 5 inches along the radians". Could either the 13 Hole Postcard or Halloween Card give us the answer to the Z13 as well? Again, totally unsolvable because of its limited number of characters, the Zodiac Killer could either keep quiet for up to fifty years or give us the answer.

From a previous article: On January 29th 1970, the Yellow Cab Company put up a thousand dollar reward for any information leading to the arrest of the Zodiac Killer. In addition, the Teamsters Union which represents the Yellow Cab Company were reported in the San Francisco Chronicle to be considering offering a further reward on February 8th 1970 in the case of Paul Stine and Charles Jarman (another taxicab murder victim). The April 20th 1970 letter gave us the code and was immediately followed by "I am mildly cerous as to how much money you have on my head now". The October 5th 1970 postcard gave us the possible solution of "Fk, I'm crackproof" and was immediately followed by "What is the price tag now". These are the only two communications in which the Zodiac Killer asked the police the price of his capture. These two communications not only had a code and an answer that fitted the code, but both were followed by the exact same question. When the Zodiac Killer was designing his 13 Hole Postcard, it is very likely he had at his disposal a copy of his original April 20th 1970 letter, or the San Francisco Chronicle newspaper cutting below, to which he was now supplying the answer. This may have been the trigger that influenced him to repeat the phrase "how much money you have on my head now" into the very similar "What is the price tag now". The Zodiac Killer, in essence, had inadvertently bound both communications together through phraseology, as well as code and solution.   

The Zodiac Killer introduction would now give us his name (albeit his initials) in absence of his full name. It would also read fluently as a sentence, as follows: "This is the Zodiac speaking. By the way have you cracked the last cipher I sent you? My name is Fk, I'm crackproof". Nobody realistically believed he was going to supply his full name, but this way he satisfies the promise in a restricted format. Two communications mailed nearly six months apart, with a solution that satisfies the code, as well as a satisfactory introduction to the code - and both followed by the same question.    

The three 8's (representing Jesus Christ in gematria), along with the number 8 which symbolizes a new beginning, actually begins each element of the phrase Fk I'm crackproof. In addition, when we begin the phrase on the first 8, it fits perfectly around the existing K and M already present in the code and thereby creating a cyclical format, where the code ends and begins with the same letter. The Little List Letter provided the solution to the Button Letter and Mount Diablo code that preceded it. His next communication, the 13 Hole Postcard, provided the solution to the 13 Symbol Cipher before that, and finally the Halloween Card provided the solution to the 340 cipher. Three chronological solves to the three previous ciphers - and the only thing we had to add was the number "5", for which he inserted the hashtag and arrow. Why look for convoluted and excessively complicated solutions to these ciphers, when the Zodiac Killer gave us all the answers literally word for word.

This isn't a case of dragging wording from the entire Zodiac collection of cards and letters, but using just the two crosshairs of the Little List Letter, followed by the 13 Hole Postcard and Halloween Card. The bold, black circle and "PS. The Mt. Diablo Code concerns Radians and # inches along the radians" to answer the Z32. The 13 holes, red cross, "paradice" and "slaves", and "sorry no cipher" to answer the Z340. And finally, "Fk, I'm crackproof" to give us a shorthanded version of his name, while still retaining his anonymity. The alternative is that the codes are genuine, the designs on the 13 Hole Postcard and Halloween Card are devoid of any purposeful meaning, and the big-headed, braggart called Zodiac, kept his lips 'butoned' for however many years afterwards.  

FOLLOW UP ARTICLE:
THE ANSWER, ORGANIZATION AND STRUCTURE OF THE SIX UNSOLVED CODES

This has been covered before, but I just wanted to expand in a little more detail without pinpointing a particular location.

How embarassing is the notion of a 50-year-old unsolved cipher, that we were given the answer to in just thirty one days? - and an answer that came straight from the horse's mouth. The 32 Symbol Cipher solution was served to us on a silver platter in the July 26th 1970 Little List Letter using the Zodiac crosshairs and six words. 

When the Button Letter was mailed on June 26th 1970, the Zodiac Killer gave us a map of San Francisco and Vicinity with his crosshairs centered over Mount Diablo, stating "the map coupled with this code will tell you where the bomb is set." If we were to find a perceived bomb, it is fairly obvious we have to travel a certain angle and distance from the top of Mount Diablo to find the location. Therefore, the 32 symbol code, if it served any purpose whatsoever, had to contain a measurement in the form of degrees and distance. The map scale was 6.4 miles to the inch - so that will be the distance the Zodiac Killer has to employ from Mount Diablo to make any sense. The degrees he used was radians, because he told us so in the July 26th 1970 Little List Letter. The Zodiac stated "P.S. The Mt. Diablo code concerns Radians + # inches along the radians". He is actually telling us that the 32 symbol code contains radians and inches in the solution.

"P.S. The Mt. Diablo code concerns (is about ) (has to do with) Radians + # inches along the radians". Any cipher expert such as David Oranchak, or quite frankly, any Joe Bloggs such as myself, will tell you that a 32 symbol code with only three repeating characters is unsolvable without a key. The Zodiac Killer was certainly no muppet - and clearly knew this when he concocted this jumble of random characters. But he gave us a large chunk of the key a mere 31 days later in the form of an arrow and a hashtag, writing "Radians and # inches along the radians" on a separate line to distinguish the very fact. We just had to key in the number. The symbol # is most commonly known as the number sign, The symbol is described as the "number" character in an 1853 treatise on bookkeeping, and its double meaning is described in a bookkeeping text from 1880. The instruction manual of the Blickensderfer model 5 typewriter (c. 1896) appears to refer to the symbol as the "number mark". Some early-20th-century U.S. sources refer to it as the "number sign", although this could also refer to the numero sign. A 1917 manual distinguishes between two uses of the sign: "number (written before a figure)"; and "pounds (written after a figure)". Mainstream use in the United States is as follows: when it prefixes a number, it is read as "number", as in "a #2 pencil" (indicating "a number-two pencil"). The one exception is with the # key on a phone, which is always referred to as the "pound key" or "pound". Thus instructions to dial an extension such as #77 are always read as "pound seven seven". Wikipedia.

All of Zodiac's bomb threats were mailed to the San Francisco Chronicle newspaper - even detailing the murder of San Francisco police officer Brian McDonnell on February 16th 1970, who suffered devastating and sadly fatal injuries when a bomb packed with fence staples exploded on an outside ledge of Park Police Station in the Upper Haight neighborhood of San Francisco. The Zodiac constantly signed off his communications with the barbed acronym SFPD = 0 and threatened "there is more glory in killing a cop than a cid because a cop can shoot back". If that wasn't enough, the Phillips 66 Road Map was labelled San Francisco and Vicinity.  Based on a map scale of 6.4 miles to the inch, only 5 inches would land in San Francisco (4 and 6 inches would fall into the sea, other than Treasure Island). Fortunately, the Zodiac Killer gave us the angle from Mount Diablo, courtesy of his bold, black circle on the Little List crosshairs. It fell 4 radians (and magnetic north) clockwise from his arrowed pointer, around the clock face he provided. Radians are usually measured counter-clockwise, but the Zodiac Killer placed the bold circle exactly 4 radians "set to Mag.N" clockwise.

The answer was now extremely simple. All we had to do was insert a number in place of the hashtag, shown by the big flashing arrow pointing us in the right direction. The hashtag conveniently preceded "inches", so it's here we will slot in the number 5 - and bingo - we have our answer to the inches component of "Radians + 5 inches along the radians" or "Radians and 5 inches along the radians". The full answer of "four radians and five inches", coupled with the magnetic north value of 17 degrees would be our guide.  As with all the best puzzles, the answer is usually hidden in plain sight. Druzer, an avid Zodiac researcher, came up with a solution to the 32 character code which I believe is correct, when he suggested Estimate: four radians and five inches. This solution not only satisfies the 32 characters, but correlates three plaintext letters to the only three repeating ciphertext characters in the code, thereby providing a perfectly valid key. See The Blast Estimate of Zodiac, The Blast Estimate of Zodiac (Part Two). and The Blast Estimate of Zodiac (Part Three). The map scale is 6.4 miles to the inch. This gives us a distance of 6.4 multiplied by 5 (inches). Therefore, the bomb was to be set at 4 radians and magnetic north, and 32 miles from the peak of Mount Diablo. The only San Francisco Police Department that comes anywhere close is Ingleside Police Station. This San Francisco Police Department sits at 30.96 miles from the peak of Mount Diablo (4.84 inches). It also sits at 251 degrees from the peak of Mount Diablo (4.08 radians).

The Zodiac Killer gave us a rough guide of 4 radians and magnetic north, and 5 inches (hence the word "estimate"). If he had given us the exact measurement, it would have been 4.08 radians and 4.84 inches, He was clearly giving us an approximate measurement. Since Ingleside Police Station was the only San Francisco Police Department anywhere close to these measurements, it's fairly obvious this was his target. The Zodiac Killer's distance in miles was 96.8% accurate. His angular accuracy in degrees was 98.0%. The Zodiac Killer was very unlikely to have selected a specific target that fell on an exact whole number of radians and inches.   

In the Little List communication it is apparent that Zodiac Killer gave us two prominent crosshairs: [1] with the accentuated black circle with SFPD=0 alongside, and [2] the extra large crosshairs with "P.S. The Mt. Diablo code concerns Radians + # inches along the radians" scrawled across it. Attaching these important additions was clearly done for purpose, thereby informing us of the radian value required, and the correlation between the crosshairs on the Phillips 66 Map and the measurements of radians and inches. With 29 unique characters in a 32 character code, any correlation between the characters and alphabetical solution was always going to be minimal, therefore it is encumbent upon us to look to other reasons for its design. The Blast Estimate of Zodiac (Part Three). 

In the final instalment of this series we will attempt to refine the previous conclusions gleaned from the Zodiac Killer letters.
The Zodiac Killer stated on April 20th 1970 "I hope you do not think that I was the one who wiped out that blue meannie with a bomb at the cop station. Even though I talked about killing school children with one. It just wouldn't doo to move in on someone else's teritory.  But there is more glory in killing a cop than a cid because a cop can shoot back.  I have killed ten people to date. It would have been a lot more except that my bus bomb was a dud.  I was swamped out by the rain we had a while back." In the correspondence, the Zodiac Killer was referring to the murder of San Francisco police officer Brian McDonnell on February 16th 1970, who suffered devastating and sadly fatal injuries two months earlier, when a bomb packed with fence staples exploded on an outside ledge of Park Police Station in the Upper Haight neighborhood. The wording in the letter suggested that the Upper Haight neighborhood was not somewhere he was prepared to venture, but the suggestion of a school bus bomb and police station, when we take into account the SFPD positioned strategically by the bold, black circle on the Little List crosshairs and indicative of a location point, brings forth the notion of a school bus bomb under the noses of the San Francisco Police Department. Targeting a school bus within sight of a police station would certainly have dealt law enforcement a mighty blow.

The Zodiac Killer may have had a location in mind, despite the fact it was never followed through on - and this location has tentatively been identified as four radians (+magnetic north) and five inches along the radian in two previous articles. The exact position he had in mind to set up his photoelectric cells to detonate the bomb didn't necessarily have to conform to these measurements exactly, just be close enough to be rounded off by the Zodiac Killer. However, the other clues he gave us in the April 20th 1970 and July 26th 1970 communications were replete with information. We narrowed down a section on Google Maps between Daly City and Ingleside in San Francisco (between 246 and 249 degrees).

To narrow down the location even futher, we should be looking for a bus route approaching a school from north to south (so the sun is rising from the east on the left side). The roadway must have sufficient embankment on its right side to elevate photoelectic switch B. It must be within the parameters of 4 radians and 5 inches (allowing for a small margin of error). The addition of the pronounced black circle within the crosshairs of the Little List Letter in the form of SFPD=0, is suggestive of a location close to a San Francisco Police Department. In other words, the Zodiac Killer may have intended his "blast" right under the noses of law enforcement: "Hey pig doesnt it rile you up to have your noze rubed in your booboos?" Despite not knowing the exact topography of this location in 1970, I have found a site just 230 feet from Ingleside Police Station alongside Southern Freeway. 

The Zodiac Killer mailed us three parts of one cipher on July 31st 1969, to the San Francisco Chronicle, San Francisco Examiner and Vallejo Times-Herald. In his communication to the Chronicle he stated "In this cipher is my idenity". Bearing in mind this is the only portion of cipher with unsolved characters, it could be argued that any identity the Zodiac was offering would be found at the signing off phase in this cipher. It didn't really matter, because only four days later he gave us his identity in the form of "This is the Zodiac Speaking". The Zodiac Killer clearly made a mistake when taking his draught message into his 408 cipher, accidentally omitting the word "people" from the final offering. If we therefore conclude his original identity to be left was actually six characters shorter, it would have reduced the 18 unsolved characters to 12. Using the first-person singular pronoun of "I", his identity at the base of the 408 cipher would read "I am the Zodiac", to become "I am the Zodiac Killer" upon realization of his mistake. The Bay Area murderer literally gave us the exact wording to his unsolved 18 characters through his introductions in the Examiner and Herald letters (both communications began with "I am the killer"). Once we knew the pseudonym or identity as Zodiac on August 4th 1969, the conversion to "I am the Zodiac Killer" was the next logical step. This would become a habit for the Zodiac Killer, who would ultimately give us the exact wording to solve his remaining three ciphers. Not only would he give us the solutions to the codes, but his practice of using 'filler' with no apparent correlation to the solution would continue.  

The Zodiac Killer was no master criminal in the style of Moriarty, but he was nobody's fool either. To make the false assumption he didn't understand ciphers or codes when creating his remaining three offerings to the San Francisco Chronicle, would be a misguided one. Even somebody with limited knowledge of coding, knows that giving us a 32 character code with 29 unique characters within its framework, is practically unsolvable without a key. You can literally fill in the blanks as you choose. Therefore, the only realistic solution to the two smaller codes can come in two forms: [1] The Zodiac Killer can give us a key to decrypt the code, or [2] He can simply give us the answer. The Zodiac Killer may well have chosen option two, and given us the entire solution to all his three unsolved codes in subsequent communications. In fact, the possibilty exists that he supplied us with all the answers in three consecutive communications from July 26th 1970 to October 27th 1970 - in the Little List Letter (07/26/70), 13 Hole Postcard (10/05/70) and Halloween Card (10/27/70). The Zodiac Killer was likely giving us all the solutions before slipping back into anonymity. The newspaper article on November 16th 1970 by Paul Avery, linking Zodiac to the Riverside murder of Cheri Jo Bates on October 30th 1966, likely drew one final breath from the Zodiac Killer through 1971, before his race was run.    

The "key" phrases for the four codes are *in this cipher is my identity", "the Mt. Diablo code concerns radians and inches",  "Fk, I'm crackproof" and "paradice and slaves". The 408 cipher we have examined, so we will now tackle the 32 symbol code.

The Little List Letter mailed on July 26th 1970, one month after the Mount Diablo code (06/26/70), told us the code "concerns radians and # inches along the radians". It was as simple as adding in two figures to complete the code (hence the hashtag symbol denoting a number). The Zodiac gave us the exact wording for the solution, detailed here in a previous article. As stated above, the 32 symbol code with 29 unique characters couldn't be solved without a key or the answer. The Mount Diablo map and crosshairs were the framework, onto which we "coupled" the code for the location of the bomb. The answer was likely "4 radians and 5 inches along the radian", thereby giving us the solution word for word. An alternative to this solution (where only the hashtag is replaced by the number 5), is "P.S. The Mt. Diablo code concerns Radians and 5 inches along the radians". The Zodiac didn't necessarily have to incorporate the number 4 because we already knew the radian value from the bold, black circle provided on the Little List Letter crosshairs.

The next solutions may have been given to us in the 13 Hole Postcard - that may ultimately become the most important communication of them all. By combining the "red crucifix" decoder and 13 punch-holes in true "Dick Tracy" style, the Paradice and Slaves formation would be revealed, bisecting the 340 cipher superficially along its mid-section both horizontally and vertically. See the article 'The Dick Tracy 340 Cipher'.  The Zodiac Killer wrote Paradice and Slaves on the Halloween card in the identical formation it could be found on the face of the 340 cipher. Three clues within the space of three weeks.

The Zodiac Killer also gave us the phrase "Fk, I'm crackproof" (upside down) on the 13 Hole Postcard. Apart from an expletive, the other viable option here, is the Zodiac Killer exclaiming that he is crackproof, preceded by his initials. The reason for this line of thinking, is the Zodiac Killer's wording before the 13 Symbol Cipher on April 20th 1970. The code is designed symmetrically and looks contrived, with three circled 8's fashioned at its center. The Zodiac Killer couldn't have supplied us with his name with any expectation it would be solved, because the code was simply too short and capable of providing us with thousands of solutions. However, he could provide us a solution to the code by giving us his initials. By doing it this way, he is in a roundabout way, giving us his name and a solution to the code that satisfies the introduction that preceded it: "This is the Zodiac speaking. By the way have you cracked the last cipher I sent you. My name is Fk, I'm crackproof".

This solution not only fits into the 13 Symbol Cipher, but reads continuously if imagined in circular fashion. The Zodiac Killer gave us three 8's within a circle (the symbol of infinity, and regeneration and rebirth within Christianity), with the letters K and M positioned ideally in the code to fit "Fk, I'm crackproof" around. There are three elements to this phrase: Fk, I'm, and crackproof. When the entire phrase is slotted around the letters K and M, the number 8 begins each element of the phrase (as shown below).

The Zodiac Killer had effectively given us the exact wording of "I am the Zodiac Killer", "Paradice and Slaves", "Fk I'm crackproof" and "Radians and (5) inches along the radians" - all of which can be inserted untouched into all four ciphers and provide us with solutions that don't require a key (The "paradice and slaves" solution would only be present on the "canvas" of the 340 cipher, so this would only be a superficial observation). The idea of a killer who constantly responded to the newspapers at every turn, somehow resisting the temptation to ever disclose the workings of his codes and ciphers is a difficult story to sell. If we are of the belief that the 32 and 13 character codes are simply too short and too variable to be solved, then without a key the Zodiac Killer likely supplied an alternative. In the case presented above, the "key" and "answer" could be described as exactly the same thing - and It was just a case of transferring the wording from one communication to another in at least three of the examples.

John Rose used Dave Oranchak's webtoy to create features of the Halloween Card in just an 81 character block around the center of the 340 cipher. Some have stated that the variability of the characters in this area of the cipher have allowed the freedom to manufacture such a result. While that may be the case, a larger pattern of Paradice and Slaves is replicated in a 17 X 17 formation along both same midsections, effectively mirroring the John Rose presentation. The fact that both are even achievable in the same cipher, is worthy of mention. The Bay Area braggart must have been itching to throw us a few clues to his unbroken codes and ciphers - so the notion that he didn't give us any before he disappeared into the twilight - is somehow difficult to swallow.   

In a previous article we concluded that the 32 character code mailed to the San Francisco Chronicle on June 26th 1970 stated "P.S. The Mt. Diablo code concerns 4 Radians and 5 inches along the radian", based upon the clues the Zodiac Killer gave us in the Little List Letter on July 26th 1970. This led to an area somewhere between Ingleside and Daly City on the south edge of San Francisco. The Zodiac drew us a bus bomb diagram on April 20th 1970, suggesting he was going to place two photoelectric switches on an embankment or hillside on the right side of the road. He stated it was to be set up early in the morning when the sun was rising in the east. The images below show the El Camino Real by Outer Mission, heading south, with the April 20th 1970 'Bus Bomb' diagram superimposed over it. The hillside to the right is the type required to place his two photoelectric switches - one by the roadside and the other higher on the banking. Any school bus heading along this road for early morning assembly, would have the sun rising in the east (shining left to right in the image below).

If the Zodiac Killer had any intentions of blowing up a school bus (which is unlikely), then he would be targeting the schoolchildren on their way to school in the morning. If the children were being bussed in from other parts of San Francisco for this particular school (St. Thomas More Catholic School), then traveling from the north and east, the bus driver could be using Highway 101 and Interstate 280 in the direction shown by the red line below (recommended on Google maps). The blue circle is 4 radians (+ magnetic north), and 5 inches from Mount Diablo, satisfying the 32 character cipher and Zodiac's statement of "P.S. The Mt. Diablo code concerns Radians + # inches along the radians". The highway under the blue circle is traveling south with the sun to the east in the morning - and is heading toward St. Thomas More Catholic School (just 1.37 miles away).      

The Zodiac Killer stated on April 20th 1970 "I am mildly cerous as to how much money you have on my head now.  I hope you do not think that I was the one who wiped out that blue meannie with a bomb at the cop station.  Even though I talked about killing school children with one. It just wouldn't doo to move in on someone else's teritory.  But there is more glory in killing a cop than a cid because a cop can shoot back.  I have killed ten people to date. It would have been a lot more except that my bus bomb was a dud.  I was swamped out by the rain we had a while back. The new bomb is set up like this. Sun light in early morning. A + B are photoelectric swiches when sun beam is broken A closes circut. B opens circut, which makes B the cloudy day disconect so the bomb won't go off by accid. PS I hope you have fun trying to figgure out who I killed".

​​The choice of words the Zodiac used at the beginning of this communication were unfortunate, had his target been children from St. Thomas More Catholic School. The school was named after Thomas More, an English lawyer, social philosopher, author, statesman, and noted Renaissance humanist. He was also a Chancellor to Henry VIII, and Lord High Chancellor of England from October 1529 to 16 May 1532. He was sentenced under the Treasons Act 1534 and decapitated with an axe. Therefore, it was very unfortunate that the Zodiac Killer should state "I am mildly cerous as to how much money you have on my head now".

There are several other schools in this area between Ingleside and Daly City, but we must remember that it is the bus he was targeting, not the school. Therefore, we should prioritize the roadways in this area (shown by the red rectangle), from the perspective of a bus traveling south, with its left side facing east.

The Zodiac Killer mailed a bomb threat on June 26th 1970, stating "the map coupled with this code will tell you where the bomb is set." One month later, realizing the inadequate information he had provided, the Zodiac Killer mailed another communication stating "P.S. The Mt. Diablo code concerns Radians + # inches along the radians", while adding some crosshairs with a black circle and the addition of SFPD = 0 alongside it. The overwhelming majority of the Zodiac Killer's communications were mailed to the San Francisco Chronicle and his taunting of the police heavily focused on the San Francisco Police Department from 1969 to 1971. If a bomb was to be set, then the Zodiac Killer was likely targeting San Francisco. He almost certainly never followed through on any of these threats, but it would be interesting to discover where his intended focus was, and find the solution to the 32 character code supplied on June 26th 1970. This topic has been covered before, but this will iron out a few problems experienced with previous articles.

The Zodiac Killer couldn't resist responding to the newspapers when he was asked to supply more details about his crimes, as demonstrated when he delivered the August 4th 1969 'Debut of Zodiac' Letter. He responded in a seven-page letter to refute the claims of Captain Martin Lee of the San Francisco Police Department, when his October 13th 1969 letter was disbelieved. He also wasn't averse to claiming various murders, disappearances and abductions that had featured in the newspapers. Despite this, the overwhelming consensus exists of a killer who remained resolutely silent on the workings of his three unsolved cryptograms or codes. However, there is every chance he gave us the exact wording that permeated the 340 cipher, to which he fashioned into the Halloween Card one year later. This was explored in the article Zodiac Admitted 340 Not a Real Cipher. I also believe he gave us the exact wording in the July 26th 1970 'Little List' Letter to solve the 32 character cipher a month earlier.

A radian value is approximately 57.3 degrees, which travel counter-clockwise. However, the Zodiac Killer placed a form of numerical clock face around the circumference of his crosshairs on the Mount Diablo map and stated that it be set to Magnetic North (about 17 degrees in 1970) - so it was considered that he had formulated his radians to run clockwise. The only radian value that can fall near San Francisco when a line is subtended from Mount Diablo, is 4 radians + 17 degrees = 246.2 degrees. Three and five radians doesn't fall anywhere near San Francisco. Therefore, a bomb set in San Francisco would have to be around the 4 radian + Magnetic North value. The bold, black circle present on the 'Little List' Letter crosshairs, falls in the region of 246.2 degrees - bearing in mind it is just a rudimentary sketch. Shown on the map above, is 2 radians counter-clockwise from True North (which would land at 245.4 degrees clockwise from True North). Both examples landing in the same region of the map. Daly City Police Department sits around 246 degrees from Mount Diablo, but resides in San Mateo County (shown by the red line). Ingleside Police Station (shown by the green line) sits closer to 249/250 degrees, but resides in San Francisco. If the Zodiac Killer had chosen a target in this region, we might expect the radian value to be only a rough guide. But it is clear, that if he is referring to a radian value, then it has to be a whole number - and it can only be 4 radians. 

Likewise, the value of inches can only be 5, if we are referring to a bomb threat in San Francisco. The scale on the Mount Diablo map is 6.4 miles to the inch. Four and six inches (25.60 and 38.40 miles) both fall into the sea on the east and west coast of San Francisco. So, unless the Zodiac Killer was wearing scuba gear and was planning to blow up an underwater school bus, the value of inches had to be the whole number of 5. When 5 inches is subtended from Mount Diablo, it gives us a value of 32 miles (somewhere in the red box below, allowing for a small margin of error). This margin of error has also been applied vertically to encompass Ingleside Police Station, bearing in mind that SFPD = 0 threat. Whether the mention of SFPD in the crosshairs on the 'Little List' Letter implies a specific threat to San Francisco itself, or somewhere close to San Francisco is unknown - but the region of San Francisco seemed the primary focus of the Zodiac Killer's communicaions during this two-year period. 

Now that we know a threat in the San Francisco region has to be subtended using the whole numbers of 4 radians and 5 inches, let us use the Zodiac's own words to complete the 32 character cipher, just like the words Paradice and Slaves from the Halloween Card was used to fill in the 340 cipher. The Zodiac Killer wrote on July 26th 1970: "P.S. The Mt. Diablo code concerns Radians + # inches along the radians". But notice the hashtag.

The symbol # is most commonly known as the number sign, The symbol is described as the "number" character in an 1853 treatise on bookkeeping, and its double meaning is described in a bookkeeping text from 1880. The instruction manual of the Blickensderfer model 5 typewriter (c. 1896) appears to refer to the symbol as the "number mark". Some early-20th-century U.S. sources refer to it as the "number sign", although this could also refer to the numero sign. A 1917 manual distinguishes between two uses of the sign: "number (written before a figure)"; and "pounds (written after a figure)". Mainstream use in the United States is as follows: when it prefixes a number, it is read as "number", as in "a #2 pencil" (indicating "a number-two pencil"). The one exception is with the # key on a phone, which is always referred to as the "pound key" or "pound". Thus instructions to dial an extension such as #77 are always read as "pound seven seven". Wikipedia.

The Zodiac Killer could easily have left the phrase as "P.S. The Mt. Diablo code concerns Radians + inches along the radians", but deliberately forced the hashtag into place to denote a number - that number being 5. The phrase would now read "P.S. The Mt. Diablo code concerns Radians + 5 inches along the radians". We know that any threat on San Francisco had to fall in the 4 radians value, so we can complete the phrase: "P.S. The Mt. Diablo code concerns 4 Radians + 5 inches along the radians". But because we have now added a specific "5 inches" to be subtended along the line of the 4th radian, the correct phrase would read "P.S. The Mt. Diablo code concerns 4 Radians + 5 inches along the radian".
An alternative to this solution (where only the hashtag is replaced by the number 5), is "P.S. The Mt. Diablo code concerns Radians + 5 inches along the radians". The Zodiac didn't necessarily have to incorporate the number 4 because we already knew the radian value from the bold, black circle provided on the Little List Letter crosshairs.

There is no way this code could realistically be solved with 29 unique characters and no key. But fortunately the Zodiac Killer realized this and gave us the answer one month later. He did the same with Paradice and Slaves in the Halloween Card, to help our understanding of the 340 cipher. So, where is the answer to the '13 Symbol' cipher mailed on April 20th 1970?

THE LOCATION OF THE BOMB [PART TWO]