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 falls into the sea).
The target of SFPD was therefore 4 radians and five inches from Mount Diablo. The target was the Southern Freeway by Ingleside Police Station, explained in greater detail here.

Whatever target the Zodiac Killer chose, it was extremely unlikely his radians and inches values would form whole numbers. This is why he gave us an estimate. On December 3rd 2020, David Oranchak, Sam Blake and Jarl Van Eycke solved the infamous 340 cipher after 51 years. On December 27th 2020, just twenty-four days later, Druzer (a regular contributor to both mainstream Zodiac forums) solved the 32-Symbol cipher. When four radians and five inches was placed into the 32-Symbol code with the word estimate, it married perfectly the three repeating ciphertext characters, giving us the complete solution to the code. The simplicity of this solution is its strength, because it doesn't require an explanation longer than the idea. I have zero doubt his solution is correct, which is why I am satisfied that the search for answers to the 32-Symbol cipher is over.

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 4.03 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 4.03 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)

The discovery of the message in the 340 cipher has triggered a new debate on the intelligence of the Zodiac Killer, bearing in mind the greater complexity of the encryption used to disguise its contents. Creating an extremely difficult cipher is actually far easier than attempting to decode it, especially when the person who designs the cipher accidentally bakes errors into his cipher as shown by the Zodiac Killer.

However, Cragle on the Zodiac Killer Site forum made an astute observation regarding the Zodiac Killer's switch from describing his hidden messages as ciphers, to codes in the June 26th 1970 and July 26th 1970 letters. While not completely true, because the Zodiac Killer stated "By the way, are the police having a good time with the code?" on August 4th 1969, it does open up the broader point of the difference between codes and ciphers, which is effectively what Cragle was implying. Codes generally operate on semantics, while ciphers operate on syntax. A cipher is a system to make a word or message secret by changing or rearranging the letters in the message, whereas a code is a system of changing entire words or phrases into something else. Codes are not just secret messages, they can be any symbol or signal used to represent, or communicate, something else.

One could argue, that if the Zodiac Killer invested the time to construct a period nineteen cipher, then he was certainly aware that by creating the Z13 and Z32  codes of such brevity and variability, he was effectively creating an impossible task and any realistic possibility of a solution without ultimately providing a key to each code. The fact that the Mount Diablo code had 29 unique characters in a 32 character array, makes it practically unsolvable without that key, A key explaining these 29 unique characters in his remaining communications appears not to be the case. The Zodiac Killer stated that "the map coupled with the code will tell you where the bomb is set", so if we take this literally, then the Zodiac Killer by June 26th 1970 expected us to solve the 32 character code with nothing more than the Phillips 66 map he supplied alongside the letter. He did supply additional clues on July 26th 1970 in the form of "P.S. The Mt. Diablo code concerns Radians + # inches along the radians", but as of June 26th 1970 he fully expected us to decipher these 29 unique characters with nothing more than a map, lending credence to the notion that this encryption was designed as a code rather than a cipher. Finding corresponding alphabetical letters to 29 unique characters appears an unlikely proposition with the limited information he provided. A man with the patience to design the 340 cipher encryption must have known this.

Sam Blake, who contributed to the solving of the 340 cipher, made an extremely valid point when stating that the decoded message was contemporary. By the Zodiac Killer claiming that "it wasn't me on the TV show", he fully expected his 340 cipher to be decoded fairly quickly. This message was for the moment, not for 51 years later. The same is probably true for the Z13 and Z32. These codes were apparently designed with the promise of a hidden name and bomb at a time when newspapers were king. When the Zodiac Killer started fading from the newspaper headlines by 1971, the ongoing quest to decipher these two codes had equally faded into obscurity. This isn't the case today, with the internet endlessly keeping the mystery and speculation alive. But as the 1970s rolled forward these codes would have faded from the publics gaze, making these puzzles much more contemporary at the time they were designed. The Zodiac Killer could enjoy the speculation surrounding his unsolved puzzles and codes while they were still being discussed in the newspapers, but once the San Francisco Chronicle and San Francisco Examiner have moved away from featuring the Zodiac Killer, the feedback surrounding his unsolved codes would equally fade away. He probably expected these two codes to remain unbroken for a limited time only.

Therefore, as Cragle intimated, we might be better rewarded by looking at the Z13 and Z32 codes through the lens of codes rather than ciphers. The search for words or phrases, in accompaniment to the limited clues he supplied, quite possibly a much more profitable avenue to go down. The solving of the 340 cipher has inevitably switched the focus of attention toward the remaining unbroken codes, with every effort being made to follow up on the success of Dave Oranchak, Sam Blake and Jarl Van Eycke. However, adopting an approach using cipher-type encryption may possibly lead to another 51 years of blind alleyways and false beliefs, scattered with the graveyards of "solved solutions" that never were.

The Zodiac Killer often responded to the newspaper articles written about him, usually in close proximity to their release. The Dripping Pen card had likely been purchased subsequent to the morning of October 25th 1969 in response to the last San Francisco Chronicle article by Paul Avery. If the 340 character cipher had been specifically designed to compliment this card, then it too was crafted subsequent to October 25th 1969. As the title attributed to this communication suggests, this greeting card featured a dripping pen on its front face, accompanied by the wording "Sorry I haven't written, but I just washed my pen". The Avery article read "Zodiac struck last on October 11 when he gunned down cab-driver Paul Stine on Washington Street in Presidio Heights. He revealed himself the killer in a letter sent to the Chronicle three days later. Since then he has remained silent".

Bearing in mind the wording "since then he has remained silent", it could be argued that the chosen card of "Sorry I haven't written" was purposefully selected in response to this article - and therefore chosen by the Zodiac Killer after October 25th 1969. The paragraph in the newspaper article also referred to Washington Street, thereby completing the phrase on the card "but I just washed my pen". The last observation is probably a little far-fetched, and heavily reliant on the Zodiac Killer being able to find a greeting card apologizing for being silent, as well as containing a word related to Washington Street. Extremely unlikely, but not impossible.

Then, the day before the November 9th 1969 'Bus Bomb' letter, came the newspaper article detailing the attempted murder of Richmond school teacher, Daniel Williams. Somebody claiming to be the Zodiac Killer made sadistic phone calls spanning October 23rd 1969 and November 2nd 1969, and culminating in a soft drink in his refrigerator being laced with arsenic. This failed murder plot may have inspired the Zodiac Killer (if the poisoner) to insinuate his continued pursuit of Daniel Williams, by stating "I though you would nead a good laugh before you hear the bad news" and "up to the end of Oct I have killed 7 people". On November 12th 1969, the San Francisco Chronicle released information on the Dripping Pen card and Bus Bomb letter under the banner of I've Killed Seven, The Zodiac Claims.

This newspaper article featured the observations of an individual with respect to the X's on the Bus Bomb crosshairs (see right). This observation was suggested in the article The Promise of Murder on Line 5.

I believe the person who initially made this suggestion was almost certainly correct. However, when I floated this idea on November 23rd 2020, I was fully aware of the Mount Diablo map and crosshairs accompanying the Button letter, which was mailed to the San Francisco Chronicle on June 26th 1970. I positioned the Bus Bomb crosshairs over Mount Diablo and rotated them slightly clockwise, so that a line drawn from the peak of Mount Diablo through four of the five X's passed directly over Lake Berryessa, Vallejo (where two attacks occurred), San Francisco and San Jose.

When we consider that this person made the observation on November 12th 1969, seven-and-a-half months before the Mount Diablo map was mailed by the Zodiac Killer (on June 26th 1970), the interpretation by this individual is extremely intriguing.  

The five cross marks cannot directly pinpoint the five claimed attacks in Benicia, Vallejo, Lake Berryessa, Presidio Heights and San Jose by superimposing them over a map. If you arrange any two X's over Lake Herman Road and Blue Rock Springs, the other three X's will never fall over Lake Berryessa, Presidio Heights and San Jose. The only way it is possible, is by placing the crosshairs over Mount Diablo (rotated clockwise} and drawing lines through the X's on the circumference. But this still leaves the 9 o' clock line unaccounted for. This is where Daniel Williams, the Richmond school teacher comes in. The sadistic phone caller to Daniel Williams may have wanted to target schoolchildren at the Richmond school where he worked (Salesian High School falls over the line drawn through the 9 o' clock position}. This is covered in the article A Killer on Line Five.

The newspaper article stated "Zodiac's letter contained five cross marks which possibly refer to attacks. Comparing these markings against a map, one interpretation that can be drawn is that they pinpoint Lake Berryessa, Vallejo (where two attacks occurred}, San Francisco and San Jose". It was effectively saying that five cross marks could pinpoint four locations (identifying Vallejo as the location where two attacks occurred). Despite classifying Lake Herman Road as Vallejo, the tight grouping of the first two attacks on the map would allow the observer to reach the same conclusion as shown in the above map. After all, this person didn't say "Zodiac's letter contained five cross marks which possibly refer to five attacks".

The Zodiac Killer likely chose Mount Diablo because of its use when surveying land boundaries in Northern California, with the summit used as the "initial point". Was it possible that the person behind the interpretation on November 12th 1969 had correctly identified Mount Diablo as the "initial point" to center the crosshairs over, by using the same reasoning as Zodiac? The Zodiac Killer himself classified Lake Herman Road and Blue Rock Springs under the banner of Vallejo (evident on Bryan Hartnell's car door), so when he provided five cross marks to signify four general locations, he was deliberately leaving the 9 o' clock line as a puzzle to the location of his next attack. He employed exactly the same technique, when substituting the X around the crosshairs with a bold, black circle around the circumference of the crosshairs on July 26th 1970, again designed to pinpoint the location of his next attack. On this occasion, it would be a school bus traveling on the Southern Freeway by Ingleside Police Station, positioned at 4 radians and magnetic north.   

After watching the very educational and insightful presentation of Let's Crack Zodiac (Part Four) by Dave Oranchak for the National Cryptologic Museum, the section about the X's positioned around the Bus Bomb crosshairs sparked a fresh interest. Dave Oranchak is correct when he identifies the difficulty regarding scale when overlaying the crosshairs over a map. The Zodiac Killer overlayed his crosshairs over Mount Diablo as part of the Button letter on June 26th 1970, which he followed up with a further clue in the Little List letter on July 26th 1970. The Zodiac Killer explicitly stated that the crosshairs were to be set to Magnetic North (17 degrees in 1970). Therefore, it wasn't particularly surprising that the center of the black circle around the circumference of the first crosshairs on the Little List letter, fell exactly at 4 radians when set to Magnetic North, ultimately identifying Ingleside Police Station as the focus for the bomb.

Two overlays were used to great effect in the June 26th and July 26th communications. It is with little doubt that the Bus Bomb crosshairs were designed to pinpoint locations as well. However, as Dave Oranchak pointed out, the scaling of such an operation is likely to lead to inaccuracy. Therefore, we have to treat the crosshairs on the Bus Bomb letter as a guide. Only a day earlier, the Zodiac Killer had listed his murder count on the Dripping Pen card, mailed to the San Francisco Chronicle on November 8th 1969. He chronologically listed the murders he was claiming by use of months, writing "Des, July, Aug, Sept, Oct = 7".

We know the Zodiac Killer had murdered five victims at Lake Herman Road, Blue Rock Springs, Lake Berryessa and Presidio Heights, but he added in the murders of Kathy Snoozy and Deborah Furlong in San Jose on August 3rd 1969. To this point, the Zodiac Killer had listed his victims, but always left us dangling with the promise of more murders. Would it be all that unusual if the Zodiac Killer again pinpointed these seven victims the following day by use of X's around the circumference of his crosshairs, just like he pinpointed 4 radians and Magnetic North around the circumference of his crosshairs in the Little List letter on July 26th 1970 - with both crosshairs overlayed over Mount Diablo. But in true Zodiac style, the promise of another location in which he would soon murder. If this were the case, we would expect one X on the circumference of the Bus Bomb crosshairs to be unknown.              

To a reasonable degree of accuracy, line [1] falls over Lake Berryessa and the murder victim Cecelia Shepard. Line [2] passes directly over Lake Herman Road and Blue Rock Springs, accounting for David Faraday, Betty Lou Jensen and Darlene Ferrin. Line [3] passes over Presidio Heights and the murder of Paul Stine. Line [4] passes over San Jose and the murders of Kathy Snoozy & Deborah Furlong. These were the locations of his seven victims which he had claimed just a day earlier. One line remains unknown. This line passes over Walnut Creek (where Elaine Davis was abducted from on December 1st 1969, and eventually murdered), as well as Richmond and San Rafael. Had the Zodiac Killer deliberately created this X on the 9 o'clock position as a teaser to his next destination of murder? Next to the bottom right quadrant of his crosshairs on the Bus Bomb letter, he wrote "Be sure to print the part I marked out on page 3 or I shall do my thing". Considering this section of text was placed next to the crosshairs with the X's, was his "thing" going to occur somewhere in the vicinity of Walnut Creek, Richmond or San Rafael, along the unknown line? As far as we know, no murders can be connected to the Zodiac Killer over the next few months in these locations, making you wonder whether this was just another threat that didn't materialize. Or it was simply just a game he was playing.  

FOLLOW UP ARTICLE: A KILLER ON LINE FIVE  

On April 20th 1970, the Zodiac Killer made reference to the murder of San Francisco police officer Brian McDonnell (44) 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 wrote "I hope you do not think that I was the one who wiped out that blue meannie with a bomb at the cop station", while simultaneously giving us a diagram of a bomb to be placed just 274 feet from another "cop station", that of Ingleside. This sense of irony didn't seem lost on the Zodiac Killer. What the Zodiac Killer knew of Brian McDonnell, other than what he read in the intervening two months is unknown, but in the remainder of his short message he stated "But there is more glory in killing a cop than a cid because a cop can shoot back". Was this just an offhand comment, or was this statement relevant to the history of Sergeant Brian McDonnell?

The Desert Sun newspaper of February 17th 1970 read: Haight Ashbury Police Station Rocked By Bomb Six Officers Injured In Blast Showering Big U-Shaped Staples.

SAN FRANCISCO (UPI) - A powerful bomb packed with U-shaped staples rocked a Haight-Ashbury District police station Monday night injuring six policemen, one of them critically. New Police Chief A. Nelder said the fused explosive was placed on the rear window sill of the sergeant’s office at Park Station in Golden Gate Park. The thunderous blast, which jarred residents for blocks around, sprayed staples through the office like miniature machinegun bullets. Sgt. Brian McDonnell fell gravely wounded with multiple head injuries. Patrolmen Robert Fogerty, 43, and Frank Rath. 27, were hospitalized with multiple puncture wounds. Officers Alfred Arnaud, 24, Robert O’Sullivan, 26. and Ronald Martin, 28, were treated for lesser injuries. “All I remember was a bomb exploded,” said one shaken officer who survived with only scratches. “I saw Sergeant McDonnell lying in the rubble, bleeding from an artery wound in his neck.” Police immediately sealed off the area and rerouted traffic. First reports indicated the building had been demolished. The blast did knock out all power in the station and shattered every window. It also demolished the sergeant’s police station wagon which was parked behind the station near Kezar Stadium, where the San Francisco Forty Niners play National Football League opponents. There were reports that a man was seen running from the station, and police later said a white and pink van was sighted leaving the area. However, there were no immediate suspects. Four days ago, three cars were blown up and two reserve policemen were injured by two bombs which exploded in a parking lot adjacent to the Berkeley police station across the bay from San Francisco. The explosive used in the Berkeley bombing was a metal pipe filled with powder and set off by a lighted fuse. The type of bomb used in the bombing of the Park police station was not determined immediately. A special U.S. Army bomb squad was summoned to the scene from the Presidio nearby. After the bombing, all district police stations in San Francisco were ordered to secure all doors and exits and post a guard.

Would it be surprising the Zodiac Killer after reading and referencing the attack on Park Police Station, that he would then focus his bomb threats in close proximity to another police station on April 20th 1970 and June 26th 1970. The diagram of the bomb location on April 20th 1970, coupled with the radians and inches values from July 26th 1970, leaves little doubt that the unfortunate murder of Brian McDonnell was the catalyst for his remaining bomb threats towards Ingleside Police Station in 1970. It is also unsurprising that after reading headlines such as "Six Officers Injured in Blast Showering Big U-Shaped Staples", that the Zodiac Killer would follow up his April 20th communication with the Dragon card on April 28th 1970, writing on the front of the card "I hope you enjoy yourselves when I have my Blast". He would repeat this approach on the card inner, stating "If you don't want me to have this blast you must do two things".

The Dragon card is thought to depict the Miguel de Cervantes Saavedra characters of Don Quixote and Sancho Panza. This may have been a deliberate choice on behalf of the Zodiac Killer, as these characters were featured in statue form within Golden Gate Park, the location of Park Police Station. The two locations are about one mile from one another. Despite claiming he wasn't responsible for the Park Station bombing, he certainly wasn't averse to mocking the police at a time of immense grief. The Zodiac Killer, despite making many threats to murder by use of bomb, constantly made excuses for not doing so. On November 9th 1969 he claimed that the bomb was ready for "future use". On April 20th 1970, the problem was "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". On June 26th 1970 he promised to annihilate a full school bus, "but now school is out for the summer". It seemed for the Zodiac Killer the lingering threat was all that was required, pouring huge doubt on him having any serious intentions of following through on his bomb threats towards San Francisco. Knowing that the police had to take the threats seriously was satisfactory enough for a killer who thrived on instilling fear in the Bay Area community.

The Zodiac Killer mailed the Button letter on June 26th 1970 promising us that the "The Map coupled with this code will tell you where the bomb is set". Thirty days later, on July 26th 1970, he would give us the near-full answer to the 32-Symbol code, which only required the number 5 added to it (Radians and 5 inches along the radians). He also drew the dark, black circle around the circumference of a second set of crosshairs to provide the exact angle we had to travel away from Mount Diablo.  However, when he constructed the Button letter, he was of the opinion that he had provided us with enough information to solve the conundrum of where the bomb was set. This in itself was a massive clue when you consider the code had only three repeating characters. The introduction to the Button letter stated "I have become very upset with the people of San Fran Bay Area. They have not complied with my wishes for them to wear some nice Zodiac buttons. I promised to punish them by anilating a full School Buss. But now school is out for the summer, so I punished them in another way. I shot a man sitting in a parked car with a .38". It is clear that this introduction has nothing to do with the code, and in no way can be manufactured to explain the meaning behind the 29 unique characters contained with the 32-Symbol code. Therefore, the solution to the 32-Symbol code was expected of us (by Zodiac) using only what he added to the Phillips 66 map. This appears impossible - but it is not. 

Obviously, the following has only been worked out in hindsight of knowing the answer to the Mount Diablo code. This is why the Zodiac Killer gave us the two crosshairs with the answers in the Little List letter a month later - he knew that the clues he gave us on the Phillips 66 map were scarce to say the least. The Zodiac Killer gave us very little when he drew the crosshairs on the Phillips 66 map, yet he still expected us to use this to solve the 32-Symbol code. This should have been the biggest clue of them all. There is absolutely no way anybody can individually decode 29 unique characters in the 32-Symbol code by using what the Zodiac Killer drew on the map, but the crosshairs on the Mount Diablo map can be used to identify where particular words began on the 32-Symbol code, from which we can then start filling in the blanks - much like the Harden's identified the double symbols on the 408 cipher to identify "kill", therefore beginning the process of decoding. Once you get your foot in the door, eventually the whole cipher starts peeling open like an orange. This exact same process had to be adopted to unravel the 32-Symbol code using the crosshairs on the Phillips 66 map. The key was devilishly simple, but extremely unlikely to have been unearthed without the benefit of hindsight. 

To unearth the position of the bomb we have to travel a certain distance around the circumference of the circle of the crosshairs, set to Magnetic North (17 degrees in 1970). Then we had to travel a certain distance away from the summit of Mount Diablo (marked as position X by the Zodiac) from that degree point. The first thing we had to discover was his likely target area. The map was of San Francisco & Vicinity, with all the Zodiac Killer's previous letters and bomb threats focused towards San Francisco and the police. Therefore, the Zodiac Killer likely expected us to explore this avenue first. But before we do that, let's explore the limited characters contained by the crosshairs above.

To find the angle around the crosshairs we have to consider that any number of degrees could fall over San Francisco from its north to south border, with no way of determining this figure from the information supplied. So, we have to look for a way of measuring an angle around the circumference of the crosshairs where only one figure is possible for the answer. This lay in the radian, because only 4 radians and magnetic north could fall inside San Francisco (beginning from his arrow pointer, set to magnetic north and traveling around the clock face he provided). No other radian value could land inside San Francisco. We now have to focus on the diagram above. Radians would travel around the circumference of the crosshairs, so let us take a punt that the repeating C in the 32-Symbol code was representative of crosshairs/circumference, and therefore the radians that traveled around them. These would be the first two words inserted into the 32-Symbol code below. 

There are two other symbols or characters inside the crosshairs on the Phillips 66 map. The first one is the X symbol, deliberately accommodated by the Zodiac Killer by not fully completing the intersecting lines of his crosshairs. He could easily have just drawn normal crosshairs over Mount Diablo and everybody would have known this was his beginning point, yet he carefully left this area free to insert the letter X. This alphabetic letter can be found in the 32-Symbol code, so let us again assume that this is the starting point for another word. The only other character visible inside the crosshairs on the Phillips 66 map is the (in part) filled-in red triangle. We will take the same approach we did with the X symbol, and assume that the filled-in red triangle is represented on the 32-Symbol code by the filled-in black triangle (again beginning a word). The black triangle is often used to depict a mountain. We now have the C, X and black triangle in the 32-Symbol code, all of which should be the beginning of words.

Just like the degrees argument above, we know that by using miles as a measurement, any number of miles from Mount Diablo to San Francisco can fall within its eastern and western borders. Therefore, the answer cannot be in miles. But using the map code of 6.4 miles to the inch only one figure of inches can fall inside the land mass of San Francisco - and that figure is five. We also know that if the black triangle in the 32-Symbol code begins a word, then that word can only be 6 letters in length before the next word kicks in with the X character. Miles doesn't fit this criteria, but inches does. We now have effectively inserted three words into our 32-Symbol code (shown below).

We know that only 5 inches from Mount Diablo lands in San Francisco, so it's now easy to insert the figure 5 before inches. We cannot insert the word "five" because "radians five radians" doesn't read fluently. Once we have added the figure 5 before inches, it's easy to add "and" into the sentence to read "radians and 5 inches". Whether the reversed letter F represented 5 is impossible to tell. The rest of the solution is now pretty easy to guess. We are left with Radians and 5 inches _ _ _ _ _ _ _ _ radians. Once a line is drawn radiating away from Mount Diablo at 4 radians and magnetic north, we then have to travel 5 inches along the 4th radian value. This gives us the final two words of the 32-Symbol code of "along the".

We now have the full answer of Radians and 5 inches along the radians. If this reasoning had been used between June 26th 1970 and July 26th 1970 and given to the police prior to the arrival of the Little List letter, the suggested solution to the 32-Symbol code would probably have been accepted when the Zodiac Killer wrote "PS. The Mt. Diablo Code concerns Radians and # inches along the radians" at the foot of the July 26th letter. Unfortunately it wasn't.

The Zodiac Killer used exactly the same concept in his 13-Symbol code by highlighting three 8's by circling them (representative of Jesus Christ, resurrection, infinity and a new beginning). These again were found to begin each element of the solution "Fk, I'm crackproof", which when inserted into the code was infinite and circular in nature. The first 8 began FK, the second 8 began IM, and the third 8 began CRACKPROOF. The letters K and M were already present in the code as an aid. Just like the 32-Symbol code, the Zodiac Killer gave us the answer to the 13-Symbol code on October 5th 1970, seemingly frustrated, or had become aware that his clues were too difficult and scarce in nature. In both the 13-Symbol and 32-Symbol codes, the Zodiac Killer created anchor points where each word was to begin. Once the month of October 1970 had rolled on by, the Zodiac Killer would never elaborate on the workings of his ciphers ever again.

The Mount Diablo Map and Code Solution    The Codes of Zodiac Never Required an External Solve

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 first three San Francisco Police officers killed in the line of duty in 1970 were Eric Zelms, murdered when he lost control of his firearm when investigating a pawn shop robbery on January 1st. The second was Brian McDonnell on February 16th 1970, who suffered devastating and sadly fatal injuries seven weeks later, when a bomb packed with fence staples exploded on an outside ledge of Park Police Station in the Upper Haight neighborhood. The third was Richard Radetich on June 19th 1970 at 5:25 am, who was 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.

The Zodiac Killer didn't personally name any of them, but referred to them indirectly when he stated "two cops pulled a goof", "I hope you do not think that I was the one who wiped out that blue meannie with a bomb at the cop station" and "I shot a man sitting in a parked car with a .38". Additonally, all three communications carried the message of his bomb-making. 

The April 20th 1970 communication not only threatened that there was "more glory in killing a cop", but provided us with imagery that showed he had already set aside a location for his school bus bomb. The Zodiac Killer had specifically chosen a bus route traveling from north to south with a steep embankment on the right and the sun rising to the east. When deciding where to place his bus bomb, one would think the killer would be drawing from experience with regards to the best location. The diagram of the bus bomb location in the April 20th 1970 letter would eventually be discovered to be the embankment directly opposite Ingleside Police Station and alongside the parking lot of the City College of San Francisco. The addition of two crosshairs on the July 26th 1970 "Little List" letter would expand on the Button letter (a month earlier), and show to a 98% accuracy that the target was the Southern Freeway embankment opposite Ingleside Police Station - which was also a bus route. This would effectively kill two birds with one stone for the Zodiac Killer. Was the Zodiac Killer familiar with the City College of San Francisco, having worked at this location or even studied there?   

The Zodiac Killer certainly wanted to paint a picture he was familiar with law enforcement practices, giving rise to the notion he may have worked at, or attended the City College of San Francisco, where he could possibly have crossed paths with Richard Radetich, who attended a criminology course prior to becoming a police officer with the San Francisco Police Department. Greg Corrales was a legendary San Francisco Police officer who knew Richard Radetich and stated that "Richard, who had recently been assigned to Traffic, regularly stopped at Ingleside Police Station to say hello to his former colleagues. He glowed when he talked about his new baby girl and his wife. He was an outstanding police officer and a devoted family man". It is clear that Richard Radetich took criminology classes at the City College of San Francisco before being assigned to duties at Ingleside Police Station just 850 feet east of the college. Richard Radetich had formerly been a student at Balboa High School, 585 meters to the east of Ingleside Police Station. This aligns Sgt. Richard Radetich at the City College of San Francisco (and likely parking lot) studying criminology, with the bus bomb designated for the eastern edge of the parking lot on an embankment, alongside a bus route traveling north to south (with the sun rising to the east), only 274 feet from Ingleside Police Station (where Radetich had worked) - and subsequently - the Mount Diablo code pinpointing this location. The Mount Diablo code letter would also indirectly reference the murder of Sgt. Richard Radetich on June 19th 1970.

It is highly unlikely that the Zodiac Killer was responsible for the murder of Sgt. Richard Radetich, with the previous observations just a simple case of unfortunate coincidences, but it still leaves pause for thought when you consider the location of the bomb had been earmarked in a letter two months in advance of his murder, on April 20th 1970. A letter that highlighted the bombing of Park Police Station and the murder of Brian McDonnell, with the claim that "It just wouldn't doo to move in on someone else's teritory". So, did the Zodiac Killer move to a territory slightly south of Park Police Station, the clue to which lay in the attached bus bomb diagram?

On February 16th 1970, a militant group placed a bomb packed with fence staples on the window ledge of the San Francisco Police Department Park Station, killing Sergeant Brian McDonnell and severely injuring and wounding nine other police officers. The Zodiac Killer had nothing to do with the brazen attack, but spurred on from his previous threats upon random police targets, managed to reference the Park Station bombing, in accompaniment to the diagram of a school bus on the Southern Freeway. The Zodiac Killer stated in the April 20th 1970 letter, that  "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". This killer had targeted six kids like sitting ducks and blindsided his seventh victim, because he was a coward. The idea that this man would target somebody who could shoot back was extremely unlikely, with the threat to escalate his attacks, more a case of creating fear and panic in the community, rather than his willingness to do so.

It was likely the newspaper coverage of the Park Station bombing that inspired his following two communications. The Dragon card mailed 8 days later, carried the introduction of "If you dont want me to have this blast you must do two things. Tell everyone about the bus bomb with all the details. I would like to see some nice Zodiac buttons wandering about town. Everyone else has these buttons like, black power, melvin eats bluber, etc". The bombing at Park Station was believed early on to be the work of the Weather Underground or the Black Liberation Army, hence the Zodiac Killer's need to get some recognition by the requesting the wearing of Zodiac buttons and referencing Black Power. It may also be significant that he placed "I hope you enjoy yourselves when I have my Blast" right alongside a picture of Don Quixote and Sancho Panza, suggestive of a location. A statue of Miguel de Cervantes, Don Quixote and Sancho Panza can be found in Golden Gate Park in San Francisco, approximately one mile from Park Station (1899 Waller Street), which also sits in Golden Gate Park, in the southeast corner. This threat of a blast, in accompaniment to the imagery, indicative of a compassionless killer piggybacking upon the Park Station bombing, by suggesting a threat in the near vicinity. An ominous foreboding that was already embedded in the April 20th 1970 letter in the form of the school bus bomb diagram. Just two months later, on June 26th 1970, the Zodiac Killer would expand on his bus bomb diagram by supplying us with extra details. 

The Zodiac Killer had given us the drawing of his intended bomb location, complete with photoelectric cells, car battery and timer. But now was the time to "clue us in" on where it was buried (or where it was threatened to be buried). The location he had designated was just three miles south of the Park Station, right alongside Ingleside Police Station on the Southern Freeway. The Zodiac Killer's threat never materialized, but somebody else did move in on his promised territory, when on August 29th 1971, Sergeant John Young was shot and killed inside the Ingleside Police Station. Two men brazenly entered the reception area and thrust a 12-guage shotgun through an opening in the bullet proof glass, striking and killing Sergeant John Young and injuring a civilian employee.

A bomb placed on the embankment of the Southern Freeway (274 feet from Ingleside Police Station) is notable for another reason. The Zodiac Killer didn't state he would "annihilate a school bus" on June 26th 1970, he promised to "annihilate a full school bus", suggesting that the school bus would have to be near the terminus of its route. The Thomas More Catholic School had a bus route along the Southern Freeway, just yards from Ingleside Police Station, passing a location mimicking the bus bomb diagram (shown below in red), with the school itself situated in the southwest corner of San Francisco. Children traveling from all over San Francisco would have been seated on this bus as it drove south in the morning light. The sun would have been to the east, with the school bus exiting the freeway extremely close to the school. It most certainly would have been full as it passed the proposed bomb location.

The Zodiac Killer threatened to kill police and place bombs, but he will be ultimately remembered for targeting the young and defenceless - and just like most serial killers - be recognized for the coward he was.  

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 32 symbol code supplied the inches component to the answer, 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 complete answer to where the bomb was to be set, was "4 Radians and 5 inches along the radian". But this wasn't the answer to the 32 symbol cipher, because the Zodiac Killer explicitly stated "The map coupled with this code will tell you where the bomb is set". The answer to the code was Radians and 5 inches along the radians (consisting of 32 characters). This is why he capitalized the first Radians and began it on a separate line. The answer to the map was the superimposed crosshairs of the bold, black circle sitting at 246 degrees (4 radians and magnetic north). The two "coupled" together gave us the full answer. 

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 248 degrees from the peak of Mount Diablo (4.03 radians).

The Zodiac Killer gave us a rough guide of 4 radians and magnetic north, and 5 inches. If he had given us the exact measurement, it would have been 4.03 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 99.3%.   

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 98%. The 32 character cipher is also answered. The Zodiac Killer 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).
Additional reading: The Anchor Points in the 32 and 13 Character Codes.    

It is without doubt that Dave Oranchak of Zodiac Killer Ciphers could explain the cryptograms and codes of the Bay Area murderer far better than me, but I am sure he would agree that the Z13 and Z32 codes, without further input from the killer, are effectively unsolvable. One is simply too short, while the other has only three repeating characters in a 32 character code. On the left is a link to Dave Oranchak's latest Youtube video, examining the faulty techniques employed by Robert Graysmith in attempting to decode the infamous Zodiac Killer 340 cipher. Just to be clear, the following examinations of the April 20th 1970 and June 26th 1970 codes are not endorsed by Dave Oranchak.

Regarding the Z32, several options exist: [1] The Zodiac Killer supplied us with a key to the code [2] There was no key supplied because the characters were not chosen for purpose (in essence they are gibberish), [3] There is no relationship between ciphertext and plaintext whatsoever, but the code has meaning only in relation to its length (ie:32 characters), or [4] There is a limited relationship between ciphertext and plaintext, but not in its entirety. When we look at the remaining communications subsequent to the 32 character offering, it is difficult to see how these could provide any explanation with respect to the 29 unique characters contained within Zodiac's Button letter code.

In a previous article, we showed how the Zodiac Killer was able to provide an answer to the Z13 and Z32, and a superficial answer to the 340 cipher in just three consecutive communications from July 26th 1970 to October 27th 1970, all in his own words (paradice and slaves visible on the "canvas" of the 340 cipher). Those three answers were essentially Paradice and Slaves, Fk, I'm crackproof and Radians and 5 inches along the radians (to be coupled with map supplying the value of 4).

A limited correlation was shown between ciphertext and plaintext in the Z13, in that the beginning of each word (component) appeared to have a relationship with each of the circled eights. The first 8 began the Fk element, the second 8 began the I'm element, and the third 8 began the crackproof element. Additonally, the letters K and M from the Fk, I'm crackproof phrase, correlated nicely with the existing K and M already in the Z13 code and completed the introduction of the April 20th 1970 letter to "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 seriously believed he would give us his full name). Therefore, at least 5 ciphertext characters appeared to have some purpose in relation to 5 plaintext characters, much like the October 27th 1970 Halloween card showed a distinct correlation to the 340 cipher "canvas". I couldn't help thinking that the same relationship between ciphertext and plaintext may have existed in the Z32, in respect to the beginning of key words within Radians and 5 inches along the radians (highlighted in red).

The first thing to notice regarding these four key words, is that "radians" is represented by the letter "C" on both occasions. "Inches" and "along" are represented by a "black triangle" and the letter "X". Bearing in mind we are looking for an angle and distance subtended from Mount Diablo to discover where the "bomb is set", this is probably where we should be looking for our answer.

Take a look at a close-up of the Mount Diablo map provided by the Zodiac Killer (shown above). Two things jump out immediately - notably the "cross" or "X" symbol, in which the Zodiac Killer made a conscious decision to not draw over with his crosshairs. And secondly, the "red triangle" (in part) representing Mount Diablo State Park. I have also added an additional symbol in the top right corner, showing that a mountain is often represented by a triangle. In the Zodiac crosshairs from the July 26th 1970 Little List letter, the killer added a "circle" around the circumference, set at 246 degrees or 4 radians and magnetic north (part of the answer). 


A line subtended from the mountain summit of Mount Diablo (triangle symbol) regarding radians and inches, radiating from the center of the crosshairs, cross or "X" symbol, through the circle on the circumference positioned at 4 radians and magnetic north - and then traveling 5 inches along this 4th radian -  is the approximate position of where the bomb was to be set. You will notice the correlation between the blue highlighted words and their relationship in the Z32 code. The beginning of "radians" is twice represented by the letter "C", the beginning of "inches" represented by the "triangle" and the beginning of "along" represented by the letter "X" of Mount Diablo. We are traveling a set amount of inches from Mount Diablo (triangle), along a line subtended from Mount Diablo (X formation), through the circle of 4 radians.  

Of course, it would be crazy to claim this was Zodiac's intention when designing the Z32 code, rather an initial and speculative look at the characters he used in relation to the plaintext solution of Radians and 5 inches along the radians, and much like the analysis of the Z13 code mailed on April 20th 1970. The Zodiac Killer had the option to design his latter two ciphers based on nothing more than their character total, but this isn't half as much fun as dropping in a few clues along the way.

THE MOUNT DIABLO MAP AND CODE SOLUTION   THE ANSWER TO THE MOUNT DIABLO CODE

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 addition, the history of Officer Richard Radetich is pertinent to the location of the bomb. 

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 (5 to be exact) and the map was to provide the radians, 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 first clue was the first set of crosshairs, where he placed the bold, black circle at 4 radians and magnetic north (246 degrees} around the circumference. This was to be placed over the Mount Diablo map of San Francisco & Vicinity, centered over Mount Diablo to give us the radian value. The second clue was therefore the solution to the 32 symbol cipher containing the inches - where he placed the hashtag and arrow for the number 5 to be inserted. Therefore we had to travel approximately 5 inches along a line subtended at 246 degrees from Mount Diablo. This is why he used the phrase "The map coupled with the code will tell you where the bomb is set". The image on the right overlayed on the map gave us the radians or degrees, coupled with the code which only contained the inches value. The bomb was to be set close to Ingleside Police Station, which to a high degree of accuracy fell extremely close to 4 radians and magnetic north, and five inches from Mount Diablo. The inches subtended from Mount Diablo at 246 degrees couldn't be more or less than 5, because a bomb (set at 4 or 6 inches) would have fell into the sea on the east and west side of San Francisco. The bold, black circle on the right, should be evident that the target was to be the San Francisco Police Department.

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 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.        

Every criteria has now been met. The school bus, the route of the school bus on a freeway, the southerly direction, the steep embankment, the target of SFPD (San Francisco Police Department) and the 4 radians and magnetic north coupled with the code of 5 inches. 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. However, there may be one other factor to contemplate, when we consider the reference to Officer Richard Radetich in the June 26th 1970 letter, containing the Mount Diablo code. The map and code took us to a location exactly bisecting Ingleside Police Station and the City College of San Francisco.

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.