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.

After two Zodiac attacks in close succession on September 27th 1969 and October 11th 1969, investigators must have feared an escalation in terror from the Bay Area murderer, so it would have certainly been in their interests to switch the Zodiac Killer's attention to communication instead of murder. On October 22nd 1969, Dr. D.C.B Marsh in alliance with investigators and the San Francisco Examiner, attempted to refocus the Zodiac Killer's attention toward creating a second major cryptogram and "reveal his name in the cipher to established cryptogram experts". Marsh would continue to press the killer throughout the article, stating "I invite Zodiac to send to The American Cryptogram Association a cipher code - however complicated - which will truly and honestly include his name". However, in order to crack any cipher the killer may send, it would have been wise to place certain triggers within the article to guide the Zodiac Killer into choosing a particular cryptographic technique. This may have been the purpose of dropping the name Edgar Allan Poe into the San Francisco Examiner article, thereby influencing the killer to choose a cryptographic technique highlighted by Poe in one of his essays. If the Zodiac Killer then responds with a second cipher, your first port of call would obviously be Edgar Allan Poe.

Although Dave Oranchak doesn't believe the Zodiac Killer used the scytale method of encryption in the recently decoded 340 cipher, this decryption tool does actually decode the message in the 340 cipher. If the Zodiac Killer responded to the prompt by Dr. Marsh and read Edgar Allan Poe's essay A Few Words on Secret Writing, he would have noticed that the first topic of discussion was the scytale cipher, which involves disguising a message by separation, avoiding the common left-to-right method of decryption. This is what the Zodiac Killer used in his 340 cipher. In further reading of A Few Words on Secret Writing, it became apparent that other encryption methods were discussed in addition to the scytale method, with the possibility existing that the Zodiac Killer may have adopted one of these techniques for his following 13-Symbol cipher on April 20th 1970. The most notable encryption methods discussed included separating the alphabet A to M, and N to Z, into two equal parts of 13 letters. Followed by a technique involving two concentric discs, akin to the Union Cipher Disk that held the number configurations of 000 and 888. These techniques show promise when we consider the design and structure of the 13-Symbol cipher. This has been covered in a much more extensive article, so it will not be covered any further here.  

Dr. Marsh, under the banner of Cipher Expert Dares Zodiac to Tell Name, would persist throughout the article into cajoling the Zodiac Killer to reveal his name by way of a cryptogram. This is why another passage in A Few Words on Secret Writing caught my attention - and may have resonated with the Zodiac Killer too. It concerned a reader sending in cryptograms to Edgar Allan Poe, but refraining from giving his name. The passage read "This challenge has elicited but a single response, which is embraced in the following letter. The only quarrel we have with the epistle, is that its writer has declined giving us his name in full. We beg that he will take an early opportunity of doing this, and thus relieve us of the chance of that suspicion which was attached to the cryptography of the weekly journal above-mentioned–the suspicion of inditing ciphers to ourselves. The postmark of the letter is Stonington, Conn".

This reminded me of the statement by Dr. Marsh when he challenged Zodiac, who he contended "had not told the truth in his cipher messages to the Examiner, the Chronicle and the Vallejo Times-Herald". He claimed "Zodiac has not done this, because to tell the complete truth in relation to his name would lead to his capture". Did the Zodiac Killer read this passage in A Few Words on Secret Writing and get some ideas?

The reader who mailed Edgar Allan Poe from Stonington, Connecticut, failed to supply his name, but did begin by placing a letter S, followed by a horizontal dash, similar to the Zodiac Killer's introduction on April 20th 1970, The Zodiac Killer began the introduction to his 13-Symbol cipher by stating MY NAME IS ---------. The sender of the cryptograms to Poe only signed his name at the bottom of the intoductory letter by use of initials, concluding with "I am yours, respectfully S.D.L." Not wanting to shy away from the challenge of Dr. Marsh a second time, I couldn't help thinking that the Zodiac Killer may have rose to the challenge and given us the initials to his name (or fictitious initials), just like the sender of the cryptograms from Stonington, Connecticut. Another thing to note, is that Dr. Marsh laid down this challenge on October 22nd 1969, so 182 days had elapsed before the Zodiac Killer's third confirmed cryptogram arrived at the San Francisco Chronicle on April 21st 1970.

Paul Avery wrote on April 22nd 1970, in an article entitled Zodiac Sends New Letter-Claims Ten, that "the killer who calls himself Zodiac has once again written to the Chronicle. In a letter received yesterday, Zodiac claims he has killed again". This letter was received by the San Francisco Chronicle on April 21st 1970, the exact day and month the letter from Stonington, Connecticut was postmarked from the anonymous sender to Edgar Allan Poe. This all may have been coincidence, but it would certainly be worth looking for the Zodiac Killer's initials as part of the answer to the 13-Symbol cipher.

That answer could be "This is the Zodiac speaking. By the way have you cracked the last cipher I sent you? My name is Fk, I'm crackproof", given to us in the Zodiac Killer's postcard five-and-a-half months later as a big hint to its decipherment. The 340 character cipher was split into rows of 9, 9 and 2 sections. The 13-Symbol cipher may have been split into 2. 2 and 9 sections, with the circled 8's beginning each section of the phrase. The letters K and M were already in place for a perfectly circular message, as highlighted in the October 5th 1970 communication by the Zodiac Killer, in which he supplied us with the phrase Fk I'm crackproof.   

On April 20th 1970, the Zodiac Killer mailed a 13-Symbol cipher to the San Francisco Chronicle, in addition to a bus bomb diagram threatening to blow up a school bus. Let's compare the 13-Symbol cipher to the 13-Hole postcard on October 5th 1970, in which the Zodiac Killer may have completed the introduction of "My name is" to "My name is Fk, I'm crackproof", again teasing us with a less than complete resolution to his real identity.

On October 22nd 1969 in the San Francisco Examiner, Dr. D.C.B. Marsh challenged the Zodiac Killer under the banner of Cipher Expert Dares Zodiac to Tell Name, to reveal something about his identity no matter how complicated. I doubt anybody with a modicum of intelligence seriously contemplated that the Zodiac Killer would supply us with his full name, however, the tactic of encouraging the Bay Area murderer to write more communications and possibly create a second cipher, had the potential to reveal more clues about the killer, while serving the secondary purpose of keeping him writing rather than killing.

On October 25th 1969, law enforcement and the newspapers headlined with Cops No Closer on Zodiac Identity, probably attempting to guide the Zodiac Killer into producing his second cipher, writing in conciliatory tone "Homicide detectives in San Francisco, Vallejo and Napa said they are no closer to catching the cryptic killer than they were ten months ago - unless some clue to his identity is among the hundreds of leads still in the process of being checked out".

The next paragraph may have been the inspiration for the next Zodiac communication on November 8th 1969. The Chronicle article continued "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". In the Dripping Pen card the Zodiac apologized by way of chosen image and wording, stating "Sorry I haven't written, but I just washed my pen". It was hypothesized that the second cipher was inspired by the language adopted in the newspapers, and the Dripping Pen card was specifically chosen in response to "Since then he has remained silent". If so, then there is a real possibility that the 340 cipher was created subsequent to October 25th 1969. 

On October 26th 1969 in the San Francisco Sunday Examiner and Chronicle they dedicated an entire section entitled Hymn to Murder, reminding the reader about the Zodiac Killer's 408 cipher, in part stating "Finally, a school teacher in Salinas broke the code by looking for the words "kill" and "killing". When deciphered, the messages proved to be a hymn to murder by an obviously disturbed person. There was, unfortunately, no clue to his identity in the cyphers".  Again, another newspaper article mentioning identity and ciphers, but this time describing them as a Hymn to Murder. Was it remotely possible that the Zodiac Killer responded to these strategic newspaper messages, bringing about the arrival of his second Hymn to Murder?

The next San Francisco Chronicle newspaper article on November 8th 1969 described the attempted poisoning of Daniel Williams, a Salesian High School teacher, on November 2nd 1969, that culminated a series of menacing phone calls by somebody claiming to be the Zodiac Killer, which began on October 23rd 1969. The language adopted in the Dripping Pen card and Bus Bomb letter strongly suggested that the Zodiac Killer may have been referring to his ongoing pursuit of Daniel Williams. In fact, the Dripping Pen card and accompanying cipher appeared a response to all of the newspaper articles beginning on October 22nd 1969 (including the attack on Daniel Williams), with the card being carefully chosen in response to Paul Avery, who stated that Zodiac had remained silent since his October 13th 1969 letter.

It is certainly possible that the 340 cipher could have been designed to relay a relatively simple superficial message, while still harboring an underlying cryptic message. A picture with a cryptographic solution under the canvas, if you will.

If the Zodiac Killer just allotted ciphertext characters to plaintext characters randomly, then how likely would it be to find the possibility of "paradice" and "slaves" bisecting the mid-section of the cipher both horizontally and vertically (17 by 17), as depicted in the Halloween card on October 27th 1970? How likely would it be for the alphabetical letters B and Y forming "BY" to fall together in each quadrant of the cipher, mimicking the Halloween card? How likely would it be for the cipher to begin with HER, forming the last three alphabetical letters of "cipher"? How likely is it that the near "Zodiac" on the final line would drop out through a randomly designed cipher? Then we have the "sorry no cipher" on the envelope inner of the Halloween card mimicking the formation of "paradice" and "slaves" in both communications.

And finally, we have the Genesis of the Hymn to Murder, found on the envelope of the Halloween card and possibly the 340 cipher. The stamp, commemorating the Apollo 8 launch on December 21st 1968, contains the words "In the beginning God", spoken by Bill Anders from the text of Genesis. This slots nicely onto the first line of the 340 cipher with the ciphertext of "GOD" positioned in acceptance at the very end. Even the half-darkened "O" looks eerily similar to the picture of the earth from the moon on the Halloween card stamp. Did "In the beginning God" introduce the Zodiac Killer's second Hymn to Murder?

In a previous article entitled The Dick Tracy 340 Cipher we explored the idea that the "13 punch-holes" and "red crucifix decoder" of the October 5th 1970 communication, may have been giving us a clue into the "Paradice and Slaves" formation within the 340 cipher. While this may remain the case, there could be a more direct link between the 13-Hole postcard and the April 20th 1970 13-Symbol cipher (and a case of dual functionality). There is the obvious link of 13 characters in the April 20th 1970 code and the 13 punched holes, but there is also the common link of phraseology in "What is the price tag now" and "I am mildly cerous as to how much money you have on my head now". These were the only two times the Zodiac Killer asked about the bounty on his capture. There is also a link between both configurations. The 13-Symbol cipher had three circled number 8's positioned in the center of the code (with 4 characters either side and two between them). The 13-Hole postcard had three distinct punch-holes in the center of the formation (with 4 punch-holes either side and two between them).

When you look at the 13-Hole postcard it is clear that the Zodiac Killer had plenty of room to configure the punch-holes into any arrangement he liked, yet he chose to overload one line with ten holes, with just three on the other. One could be forgiven for believing there was purpose in this design. 

The April 20th 1970 and October 5th 1970 communications were littered with Christian symbolism. We have the Red Crucifix, the three 8's (which in Christian numerology represents Jesus, or Christ the Redeemer), the Celtic Cross and the Anchor (adopted by Christians as a symbol of hope in future existence). The number 8 (infinity) in Christianity is representative of eternal life, rebirth, regeneration or a new beginning. They all play into the belief of an afterlife. This brought forward the notion that the number 8 in the 13-Symbol cipher was the beginning of each element of the phrase "Fk, I'm crackproof" (as shown above in green). In the diagram above, one can see that the letter F becomes the 5th letter in both sequences, the letter I becomes the 7th letter in both sequences, and the letter C becomes the 9th letter in both sequences, with the K and M slotting in between. In short, the letters FIC in both instances are separated into three circles, positioned identically in both sequences. The use of circles in both the 13-Hole postcard and 13-Symbol cipher plays directly into the phrase "Fk I'm crackproof", which when placed around the already existing K and M in the code, forms an eternal and circular repeating sequence. The April 20th 1970 communication now satisfied the October 22nd 1969 challenge by cryptographer D.C.B. Marsh in the San Francisco Examiner, for the Zodiac Killer to reveal his name. The 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".                

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".

In a previous article, The Secret Codes of Zodiac, we explored the idea that cryptographer D.C.B. Marsh dropped the name Edgar Allan Poe into his San Francisco Examiner newspaper article on October 22nd 1969, hoping that Zodiac would take the bait and design a cipher using techniques employed or featured by Edgar Allan Poe in one of his essays. We showed how the 13 character cipher of April 20th 1970 resembled a cipher technique shown in A Few Words On Secret Writing. The alphabet in both instances seemed split into two halves, with the 13 character Zodiac cipher beginning with A and ending with M. There was also a letter-writer who contacted Poe but "declined giving his name in full", dating the envelope April 21st 1841. Additionally, there was a Dick Tracy style technique mentioned in A Few Words On Secret Writing similar to that employed by Zodiac in his 340 cipher, 13 Hole postcard and Halloween card. But what if there was a cryptographic technique featured in A Few Words On Secret Writing that could directly produce the figure 888, clearly visible front and center of the Zodiac Killer's 13 character cipher. 

The Zodiac Killer had certainly made the figure eight the centerpiece of his coding on April 20th 1970, not only using three, but circling them as if to imply greater meaning. Was the circling of the number eights a hint towards the technique used in the coding? When we look at the first paragraph of A Few Words On Secret Writing, it features a technique using two wooden cylinders (scytala) as a method of coding, but directly underneath the example of coding in the essay, where the alphabet is split A to M, and N to Z, lies the important paragraph  It states;

A letter composed of such characters would have an intricate appearance unquestionably. If, still, however, it did not give full satisfaction, the idea of a perpetually shifting alphabet might be conceived, and thus effected. Let two circular pieces of pasteboard be prepared, one about half an inch in diameter less than the other. Let the centre of the smaller be placed upon the centre of the larger, and secured for a moment from slipping; while radii are drawn from the common centre to the circumference of the smaller circle, and thus extended to the circumference of the greater. Let there be twenty-six of these radii, forming on each pasteboard twenty-six spaces. In each of these spaces on the under circle write one of the letters of the alphabet, so that the whole alphabet be written — if at random so much the better. Do the same with the upper circle. Now run a pin through the common centre, and let the upper circle revolve, while the under one is held fast. Now stop the revolution of the upper circle, and, while both lie still, write the epistle required; using for a that letter in the smaller circle which tallies with a in the larger, for b that letter in the smaller circle which tallies with b in the larger &c. &c. In order that an epistle thus written may be read by the person for whom it is intended, it is only necessary that he should have in his possession circles constructed as those just described, and that he should know any two of the characters (one in the under and one in the upper circle) which were in juxta-position when his correspondent wrote the cipher. Upon this latter point he is informed by looking at the two initial letters of the document, which serve as a key. Thus, if he sees a m at the beginning, he concludes that, by turning his circles so as to put these characters in conjunction, he will arrive at the alphabet employed.

We know the Zodiac Killer often drew his inspiration from deep history, such as the short story The Most Dangerous Game by Richard Connell, first published on January 19th 1924, and The Mikado (1885), so what if he took this concept of two circles with a common center and looked for a cipher technique he could plagiarize in his April 20th 1970 letter. But more importantly, a technique of coding that had previously featured three eights (888) in its design.  

The Union Cipher Disk from the American Civil War was 3.75 inches (95 mm) in diameter and made of light yellow heavy card stock. It consisted of two concentric disks of unequal size revolving on a central pivot. The disks were divided along their outer edges into 30 equal compartments. The smaller inner disk contained letters, terminations and word pauses, while the outer disk contained groups of signal numbers. For easier recognition, the number eight represented two. The initials A.J.M. represent the Chief Signal Officer General Albert J. Myer.

A cipher disk is an enciphering and deciphering tool developed in 1470 by the Italian architect and author Leon Battista Alberti. He constructed a device, (eponymously called the Alberti cipher disk) consisting of two concentric circular plates mounted one on top of the other. The larger plate is called the "stationary" and the smaller one the "moveable" since the smaller one could move on top of the "stationary". The first incarnation of the disk had plates made of copper and featured the alphabet, in order, inscribed on the outer edge of each disk in cells split evenly along the circumference of the circle. This enabled the two alphabets to move relative to each other creating an easy to use key. Rather than using an impractical and complicated table indicating the encryption method, one could use the much simpler cipher disk. This made both encryption and decryption faster, simpler and less prone to error. Wikipedia.

The single and triple 8 number is featured heavily within the design of the Union Cipher Disk, with the 888 representing "tion".
Not only did the split alphabet of Edgar Allan Poe's 13 characters appear in the Zodiac code of April 20th 1970, along with the near date of April 21st, but the concentric circle cipher technique explicitly detailed in A Few Words On Secret Writing, can be found in the American history of the Union Cipher, with the number 8 front and center of everything, including the number 888.

On October 22nd 1969, the San Francisco Examiner and Dr. D.C.B. Marsh of The American Cryptogram Association designed a newspaper article with the express intention of trapping the narcissistic Zodiac Killer into inadvertently giving us his name, by carefully dropping key words into the framework of the article. The Zodiac Killer, it can be argued, took up the challenge and was led by the wording in the article. Dr. D.C.B. Marsh stated "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 Allan Poe, that any cipher created by man can be solved by man". 

It is perfectly conceivable that by dropping the name of Edgar Allan Poe, who was synonymous with coded challenges to his audience, into the newspaper article in an offhand way, Dr. D.C.B. Marsh was probably hoping the Zodiac Killer would use the techniques of Poe in offering us his name in subsequent ciphers. This would allow Marsh to narrow down the avenues of encryption used in any future Zodiac correspondence. When we consider the November 8th 1969 and April 20th 1970 codes of Zodiac, in comparison to Poe's A Few Words on Secret Writing, it is conceivable that the Zodiac Killer brought an essay from the last century into the heart of the Bay Area and presented this historic offering to The American Cryptogram Association.

So, after reading this newspaper article, the Zodiac Killer toddled off to the nearest library and searched for the works of Edgar Allan Poe. He arrived at A Few Words on Secret Writing - and remembering that Marsh had invited him to create a cipher "however complicated" - the Zodiac Killer took a prompt from the Poe essay and did completely the opposite. Wouldn't it be expected by observers, having had his 408 cipher cracked in a matter of days by the Harden's - and being challenged by Marsh to create a cipher "however complicated" - that the Zodiac Killer would dish out the mother of all ciphers. A cipher so devilishly fiendish, we would still be sweating over it 50 years later. The Zodiac Killer, knowing this would be expected of him, did completely the opposite and created a cipher on November 8th 1969 so unbelievably easy, that it still slipped through the cracks of the over-thinking mind. Not only that, but he got his idea from the wording of Edgar Allan Poe, as Marsh had hoped. 

The essay of Poe stated "Many of the cryptographs were dated in Philadelphia, and several of those which urged the subject of a bet were written by gentlemen of this city. Out of, perhaps, one hundred ciphers altogether received, there was only one which we did not immediately succeed in resolving. This one we demonstrated to be an imposition — that is to say, we fully proved it a jargon of random characters, having no meaning whatever". The Zodiac Killer wasn't one in a hundred, more like one in several million, so he certainly wasn't going to play by the rules. He now knew that he was going to create a cipher of nonsense, but not entirely without meaning.

The Zodiac Killer studiously continued down the essay just one paragraph, until the wording triggered off the second light bulb in his head. It stated "A very common, and somewhat too obvious mode of secret correspondence, is the following. A card is interspersed, at irregular intervals, with oblong spaces, about the length of ordinary words of three syllables in a bourgeois type. Another card is made exactly coinciding. One is in possession of each party. When a letter is to be written, the key-card is placed upon the paper, and words conveying the true meaning inscribed in the spaces. The card is then removed and the blanks filled up, so as to make out a signification different from the real one. When the person addressed receives the cipher, he has merely to apply to it his own card, when the superfluous words are concealed, and the significant ones alone appear. The chief objection to this cryptograph is the difficulty of so filling the blanks as not to give a forced appearance to the sentences. Differences, also, in the handwriting, between the words written in the spaces, and those inscribed upon removal of the card, will always be detected by a close observer".

Or, the card is punched with 13 holes, which when placed in true 'Dick Tracy' style over the 340 cipher, reveals the skeletonized version of Paradice and Slaves bisecting the cipher, 17 by 17 in cruciform. The rest of the 340 cipher filled with random noise, but fashioned in such a way to give the appearance of design, by forming the tell-tale signs of a real cipher. The Zodiac Killer even had the brazen cheek to correct one character of nothing, thereby feeding the false notion of a cipher he was conscientiously trying to get right. He even had the time to sign his work of art on the bottom line of his masterpiece. A work of art, but a work of fiction, that has been believed as credible for longer than Robert Graysmith. 

Several paragraphs later, and in order, the Zodiac Killer arrived at the Marsh trigger. Remember the challenge laid down by the eminent cryptographer: "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, which will truly and honestly include his name". This challenge is whirring around Zodiac's brain when he observes the piece of text in Poe's essay that mimics the challenge of Marsh. The text reads "This challenge has elicited but a single response, which is embraced in the following letter. The only quarrel we have with the epistle, is that its writer has declined giving us his name in full. We beg that he will take an early opportunity of doing this, and thus relieve us of the chance of that suspicion which was attached to the cryptography of the weekly journal above-mentioned — the suspicion of inditing ciphers to ourselves. The postmark of the letter is Stonington, Conn. S———————, CT., APRIL 21, 1841".

When we consider the challenge of Dr. D.C.B. Marsh to encourage the Zodiac Killer to give us his name in cipher form, with an encryption technique of a split alphabet presented in A Few Words on Secret Writing (shown below) - in combination with the postmark of April 21st above - then it is rather revealing that Zodiac should begin his April 20th 1970 cipher with "This is the Zodiac speaking. By the way have you cracked the last cipher I sent you. My name is....", and form it into 13 characters beginning with A, and ending with M. The Zodiac Killer was kind of mischievous like that.

It turned out that Zodiac didn't give us his name in full in the 13 character cipher, but he did give us something. 

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

It is now fairly clear that the Tim Holt comic book connection, discovered by Tahoe27 in 2013, was integral to the Zodiac Killer agenda from the very outset. His determination to gather slaves for the afterlife by way of gun, knife, rope and fire, was probably rooted more in fantasy than reality, but it would feature heavily through four cryptic communications. When the Zodiac Killer realized there was inadequate information in the June 26th 1970 Mount Diablo code, he rectified the situation in just 30 days, giving us the answer to where the bomb was set via two prominent Zodiac crosshairs and a small piece of text. When the Zodiac Killer crafted and mailed the 340 cipher on November 8th 1969, he again gave us insufficient information to decode. However, he did state "PS could you print this new cipher in your frunt page?" But just like the Mount Diablo code to which he gave us the answer in 30 days, he would give us the full answer to the 340 cipher in only 29 days.

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.

The notion of a Zodiac Killer, who bragged, boasted and put pen to paper at every opportunity, is seemingly disregarded when it comes to his codes and ciphers. We are led to believe that a killer with marker pen diarrhea, writing to the newspapers on an almost monthly basis for two years, managed to keep his big fat trap shut for just over fifty years with respect to his codes. The designs in the December 7th 1969, December 16th 1969 and October 27th 1970 communications suggest otherwise. He would give us the answer to the 340 cipher in just 29 days (albeit inadequate), and give us the answer to the Mount Diablo code in only 30 days, when the Little List letter rolled along. The idea of a killer with extreme patience, upwards of 50 years, is not a killer I recognise.  

The following will be extremely speculatory and should not to be taken too seriously, but I wanted to examine the prompt by Professor D.C.B. Marsh who told the Examiner on October 22nd 1969: "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".

When recently promoting the notion of a killer providing us with all the solutions to his ciphers in Three Months After the Mount Diablo Code, it was considered that the Zodiac Killer did respond to Dr. Marsh, but he certainly wasn't going to be as forthcoming as to provide us with his full name as Dr. Marsh had honestly requested. Hence the idea that he did give us his name, albeit in the abridged version of his initials which he supplied to us in the October 5th 1970 '13 Hole' Postcard. When this was slotted into the April 20th 1970 '13 Symbol' Cipher it read like so: "This is the Zodiac speaking. By the way have you cracked the last cipher I sent you? My name is Fk, I'm crackproof". The Zodiac Killer had in effect answered the request of Dr. Marsh, although in a rather devious manner. However, Dr. Marsh issued this challenge on October 22nd 1969 and the 340 Cipher came before the 13 Symbol Cipher.     

One of the most prominent features in the 340 Cipher is the sixth line where he corrects a forward facing K to a backwards facing K, similar in nature to the way he reversed the "Fk, I'm crackproof" phrase on the 13 Hole Postcard. The proximity of F and K can be noted in these two outstanding features - and possibly the Zodiac thought it mildly amusing to provide his name to Dr. Marsh in the extremely "complicated" manner of reversing his name or initials. Everybody was searching for a stunningly complicated solution to the 340 character cipher as Dr. Marsh had requested, so the Zodiac Killer gave us the complete opposite.

The connection between the 13 Hole Postcard and 13 Symbol Cipher was not only bound in the "Fk, I'm crackproof" solution, but the two phrases he used in each communication didn't go unnoticed either. The Zodiac Killer inextricably tied the two correspondences together using similar phraseology, such as "What is the price tag now" and "how much money you have on my head now". 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). This news was likely what prompted the Zodiac Killer to open this communication with the words "I am mildly cerous as to how much money you have on my head now".  Or could there be another more subtle clue in these phrases with regard to his name?

Where on the April 20th 1970 letter and throughout much of his communications to date (including the 340 Cipher) could money or a price tag be found on a head? The 13 Symbol Cipher letter carried a dated 1966 Franklin D. Roosevelt stamp, where indeed "money" or a "price tag" could be found 'on' the head of Franklin D. Roosevelt. Was this a subtle hint to his first name of "Franklin" or "Frank". This would satisfy the F part of "Fk, I'm crackproof" - but as stated earlier,  very speculative to say the least.

Another communication where he promised us his name was the October 27th 1970 'Halloween' Card, in which he gave us an odd-looking symbol and placed it on the left side of the envelope and the Halloween Card inner, followed by the letter Z. The correct way to address an envelope is to write the sender's name and address in the top left corner of the envelope, shown here on a Youtube video, and the recipient address (in this case Paul Avery) in the center of the envelope. Therefore, this strange symbol could equate to the sender's name. Since we are looking for the initials of the Zodiac Killer (which may be reversed for a third time), it is extremely promising that we have an F looking character on the right side yet again. I don't like too much manipulation and the use of mathematics anymore, but on this occasion I will choose the path of least resistance and take the 7 and 4 dots to equal 11 (K being the 11th letter of the alphabet) - and therefore give us a joined K and F for his name on the return section of the envelope. Unfortunately, manipulation such as this always leads to the possibility of multiple solutions, so we have to be guarded to any conclusions we make. Finally, I would like to take a look at the sister card to the Halloween Card mailed in the December of 1990. It too promised us his name.       

The greeting card was again from our Secret Pal just like the Halloween Card twenty years earlier - it began with the message "FROM YOUR SECRET PAL CAN'T GUESS WHO I AM YET? WELL, LOOK INSIDE AND YOU'LL FIND OUT". Then promised to keep us guessing on the card inner.

All the Zodiac Killer added to the card inner was a Xerox copy of some "keys". It really couldn't be any simpler. The card outer stated "From your secret pal, can't guess who I am yet? Well, look inside and you'll find out" followed by "keys". This may very well be the final really complicated answer to the challenge laid down by Dr. Marsh all those years earlier. The surname of Keys, Keyes or Keays would satisfy the K of FK, from the phrase "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 mocking response to Professor D.C.B. Marsh, who requested that the Zodiac Killer "send The American Cryptogram Association a cipher code - however complicated - which will truly and honestly include his name" was probably befitting of the Zodiac Killer. The answer may have been simpler than we could ever of imagined. Return to sender: Franklin Keys (or alternate options above).

Of course, I am not claiming this to be the answer regarding the identity of the Zodiac Killer, but it would be rather appropriate for the Zodiac Killer to have begun his letter writing campaign with Franklin on the stamps of his July 31st 1969 trinity of communications, and ended with his surname of Keys in 1990 - and thumb a finger to all the cipher experts trying vainly to crack his extremely complicated ciphers, when the answer was literally staring us in the face all along. 

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 Zodiac Killer mailed the Paul Stine letter to the San Francisco Chronicle on October 13th 1969 and stated "I am the murderer of the taxi driver over by Washington St + Maple St last night, to prove this here is a blood stained piece of his shirt. I am the same man who did in the people in the north bay area". Bearing in mind that the murderer had previously referenced the murders at Lake Herman Road and Blue Rock Springs Park under the umbrella of Vallejo on the car door of Bryan Hartnell's vehicle, it is clear that the switch to the north bay area was deliberately chosen to incorporate his latest attack at Lake Berryessa. The North Bay is a subregion of the San Francisco Bay Area, in California, United States. The largest city is Santa Rosa, which is the fifth-largest city in the Bay Area. It is the location of the Napa and Sonoma wine regions, and is the least populous and least urbanized part of the Bay Area. It consists of Marin, Napa, Solano and Sonoma counties. This is just the first of many times he referenced his Lake Berryessa attack on Bryan Hartnell and Cecelia Shepard, which claimed the life of the young woman. The November 8th 1969 'Drippng Pen' Card and 340 character cipher were pivotal to the Lake Berryessa attack in a number of ways.      

Up to this point, the Zodiac Killer had given us details of the two attacks in Benicia and Vallejo with "some facts which only I + the police know". and confirmed he was the murderer of Paul Stine by the addition of the blood stained shirt piece in the October 13th 1969 letter. Why should he then mail two communications in near tandem with one another, if one of them was not a belated offering? The wording on the front of the card, stating "Sorry I haven't written, but I just washed my pen" appeared chosen for purpose, because Lake Berryessa was the only attack he hadn't written about. Maybe it took the Zodiac time to search for an appropriate message and card, which fitted the bill regarding his exploits by the lake. Once he found a suitable card, he designed his 340 character cipher and mailed it alongside the Bus Bomb Letter, franked one day apart. If this were the case, then it's highly probable that the message in the 340 is relevant to Lake Berryessa as well.

The image and writing on the card outer marries up perfectly with the Zodiac message on the card inner. The Zodiac supplied us with his crosshairs, which underneath he wrote the months of his claimed attacks ("Des, July, Aug, Sept, Oct = 7"). This mirrored the message he wrote on the car door of Bryan Hartnell's vehicle, where he also added the months of his crimes, thereby generating another link to the crime. These were the only two occasions he did this. The reason for the 'Dripping Pen' Card choice, was because when he wrote on the car door with the same hand that he had stabbed the young couple, he transferred blood onto the pen - and hence the sardonic introduction of "Sorry I haven't written, but I just washed my pen" and the imagery shown.

If the Zodiac Killer apologized for not having written because his blood stained pen had been washed and gave us his attack months on the card inner - thereby replicating the design on the car door - then one could expect the "by knife" attribution to be present somewhere in the card or cipher as well. The card outer and card inner were inextricably linked by the act of Zodiac writing on the car door after the Berrryessa attack. Investigators asked the Zodiac Killer to confirm the "by knife" writing to prove he was the murderer and he duly obliged in the 340 character cipher. The Zodiac Killer placed "death by knife" in the bottom left quadrant of the 340 cipher and was confident that investigators wouldn't "get the news for a while". This turned out to be true, because the Zodiac Killer had to show us the workings of the 340 cipher nearly a year later, using By Fire, By Gun, By Rope, By Knife, Paradice, Slaves and Sorry No Cipher. 

Tahoe27 found the link between the Halloween Card and the Tim Holt comic book, where victims were placed on a Death Wheel. The four prominent execution methods featured on the cover were Death By Fire, Death By Gun, Death By Rope and Death By Knife, with the executioner spinning the wheel. Therefore, is it any great surprise that the Zodiac Killer turned up at Lake Berryessa dressed as an executioner and wrote "by knife" on the car door. This strongly suggests that the Tim Holt comic book not only played a major part in the October 27th 1970 Halloween Card, but in the Lake Berryessa attack, murder of Cecelia Shepard and the design of the 340 character cipher. The two communications mirror each other perfectly, with the Halloween Card even designed with an eye peering from behind a tree, mimicking the Lake Berryessa attack where Zodiac hid behind a tree to don his costume. For more information on the parallels between the Halloween Card and 340 cipher, please read Zodiac Admitted 340 Not a Real Cipher and The Answer to the Z38 Code.

However, we mustn't forget that the months and total provided on the 'Dripping Pen' Card only referenced the Zodiac's claimed murder victims (the Aug attribution referring to the August 3rd 1969 Snoozy/Furlong murders). This may suggest that the 340 character cipher only contained a basic message with regards to the murder of Cecelia Shepard - and why the cipher began with the word "Her". The "By Knife" phrase in the bottom left quadrant of the 340 cipher was, in effect, the Zodiac Killer supplying the answer to investigators about the writing they concealed on the car door. Nobody said Zodiac was going to make it easy and play by the rules. The "By Knife" attribution was in fact "Death By Knife" from the wheel of the Tim Holt comic book. 

If we now read the 'Dripping Pen' Card from outer to inner, and through the 340 cipher, it effectively reads "Sorry I haven't written about the Lake Berryessa attack, but I just washed my pen of the blood. Des, July, Aug, Sept, Oct = 7. Her death by knife. Zodiac".

The Halloween Card curiously contained 4-TEEN on the Lake Berryessa depiction. Only four teenagers had been murdered and claimed by Zodiac on November 8th 1969. They were David Faraday, Betty Lou Jensen, Deborah Furlong and Kathy Snoozy. Two communications forever linked.

# In medieval and ancient philosophy the Wheel of Fortune, or Rota Fortunae, is a symbol of the capricious nature of Fate. The wheel belongs to the goddess Fortuna (Greek equivalent Tyche) who spins it at random, changing the positions of those on the wheel: some suffer great misfortune, others gain windfalls. The metaphor was already a cliche in ancient times, complained about by Tacitus, but was greatly popularized for the Middle Ages by its extended treatment in the Consolation of Philosophy by Boethius from around 520. It became a common image in manuscripts of the book, and then other media, where Fortuna, often blindfolded (second skeleton), turns a large wheel of the sort used in watermills, to which kings and other powerful figures are attached. The origin of the word is from the "wheel of fortune" - the zodiac, referring to the Celestial spheres of which the 8th holds the stars, and the 9th is where the signs of the zodiac are placed. The concept was first invented in Babylon and later developed by the ancient Greeks. Wikipedia.

In the article Three Months After the Mount Diablo Code we showed how the Zodiac Killer gave us the answers to his three main unsolved ciphers in three consecutive communications spanning July 26th 1970 to October 27th 1970. Here we will do exactly the same thing regarding the December 7th 1969 Fairfield Letter (the companion to the December 16th 1969 letter). The December 7th 1969 letter showed traits of the 408 cipher, in which the author had simply dragged characters from above to provide filler for the remaining 18 unsolved characters. In the December 7th 1969 letter he had dragged groups of characters from the 340 cipher in similar fashion. 

Tahoe27 made an excellent discovery when she linked the October 27th 1970 Halloween Card to the Tim Holt comic book, showing the connection to the configuration displayed on the card in the wording By Fire, By Gun, By Rope and By Knife. However, the Zodiac Killer had likely made this connection much earlier than October 27th 1970, when he designed the December 16th 1969 Fairfield Letter (shown on the left}. In this communication he gave us a rudimentary design of the Halloween Card configuration preceded by the word "death", thereby satisfying the Tim Holt comic book of "Death By Fire, By Gun, By Rope and By Knife. Below I have shown the interconnectivity between the Halloween Card, 340 cipher and both Fairfield letters, demonstrating how the Tim Holt comic book played a part in the design of them all, with By Fire, By Gun, By Rope, By Knife, Paradice and Slaves the running theme.

The December 16th 1969 Fairfield Letter was essentially a very rudimentary precursor to the Halloween Card design of By Fire, By Gun, By Rope, By Knife, Paradice and Slaves. It was also very likely a clue to the December 7th 1969 code scribbled at the base of that letter, containing 38 characters. If this code followed the same way as all the others, in that the Zodiac Killer simply provided us with the answer to his codes in later communications, then what are the chances the solution depended on the wording in the Halloween Card, which mimicked the design of the second Fairfield Letter?

The December 16th 1969 Fairfield Letter stated "Look for more blood", then provided us with the Halloween Card style design of large crosshairs surrounded by four smaller crosshairs in each quadrant, intended to signify By Fire, By Gun, By Rope, By Knife, Paradice and Slaves. But the Zodiac Killer inexplicably chose the over inflated promise of 38 more victims from San Francisco, San Jose, Vallejo, Napa, Fairfield, Sacramento and Oakland. Curiously, the exact same number as characters on the December 7th 1969 Fairfield Letter. These victims, likely to be murdered By Fire, By Gun, By Rope and By Knife. So, was there a correlation between the two letters using these words? You will notice that the code above hasn't been structured uniformly like the 408 and 340 ciphers, but 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, satisfying the non-uniformity displayed by the 38 character code. We now have By Fire, By Gun, By Rope, By Knife, Paradice and Slaves running through four communications - that of the Halloween Card, 340 cipher and both Fairfield letters. The Zodiac Killer yet again supplying us with the answer to one of his codes in subsequent communications.