On December 3rd 2020 David Oranchak, Sam Blake and Jarl Van Eycke unlocked the mystery to the 51-year-old 340 cipher, mailed by the Zodiac Killer on November 8th 1969. On December 7th 1969, the Zodiac Killer mailed a communication from Fairfield containing a 38 character code, yet to be broken. In recent years I have had little doubt that this letter was genuine Zodiac material, but the solving of the 340 cipher put to rest any lingering doubt regarding its authenticity.

​The author of the 38 character code prominently featured two sections of the 340 cipher, that included the beginning 4 ciphertext characters of the 340 cipher, and the last 5 ciphertext characters of the 340 cipher. The only logical reason for the Zodiac Killer to have done this, would have been to give us a clue to the solving of the 340 cipher. When the code key is applied to the 340 cipher before any period 19 (diagonal shift), the first 4 plaintext characters of the 340 cipher spell IRON. The last 5 plaintext characters spell DEATH. As previously pointed out, a hoaxer would have had to be extremely lucky to keep the beginning and ending of the 340 cipher intact, to the tune of 4 & 5 characters (when creating the Z38), that just happened to create two English words in these notable positions. One would have expected a lazy hoaxer to replicate ciphertext characters 333 to 338 in the 340 cipher, because these characters were close to the spelling of "Zodiac". But the author of the December 7th 1969 letter refrained from doing this, choosing to separate these 6 ciphertext characters, so as to form the word DEATH at the end of the 38 character code. 

After the solving of the 408 and 340 cryptograms in 1969 and 2020, there is a strong argument to be had, that the Zodiac Killer's remaining unbroken codes also contain a message, which includes the Z38 mailed just one month after the 340 cipher. I have attempted to tackle the Z38 code, but it needs an expert in code breaking to take a look at this encipherment, such as Dave Oranchak, who I believe could shed more light on this small code. The message beneath - at the very least - should provide a little more insight into the thinking of the Zodiac Killer during this crucial period. 

Did the Zodiac Killer create the 38 character code so soon after his November 8th 1969 offering as a prompt to the solution of the 340 cipher? I hope Dave Oranchak will take a look and possibly correct some of the incorrect assumptions I may have made. Thanks to Druzer, a regular contributor to both main Zodiac forums, for his assistance in this matter.
CLICK HERE FOR UNOBSTRUCTED VIEW OF CODE.

Professor D.C.B. Marsh told the San Francisco 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 Allan 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 Zodiac Killer responded on November 8th 1969 by using the scytale method of decryption featured at the top of Poe's essay A Few Words On Secret Writing. Or should I say, it can be used to crack the 340 cipher encrypted message, that contained the wording "one in paradice" just like Edgar Allen Poe's poem to his dead wife entitled "To One In Paradise". The next method of encryption in Poe's A Few Words On Secret Writing involved splitting the alphabet A to M and N to Z (two sections of thirteen) mirroring the Zodiac's 13 character code which began with A and ended with M - and because of the distinct lack of characters in this code - it has been considered unsolvable using standard cryptographic methods.

​The Zodiac seemingly didn't supply us with a key to this code in later communications, leading me to believe that the key or answer lies in the Edgar Allen Poe essay mentioned above. I believe the answer to the code is ​"This is the Zodiac speaking. By the way have you cracked the last cipher I sent you? My name is....Fk, I'm crackproof, in which each element of the phrase is begun by each of the circled eights, thereby creating an infinite circular cipher (hence the circled 8's which represent infinity and a new beginning). The Zodiac Killer may have supplied us with the answer to the Z13 code in the 13-Hole postcard on October 5th 1970 in which he configured the punched holes in an arrangement of 10 to 3, pinpointing the position of the three eights, and supplying the answer of Fk, I'm crackproof. Using Edgar Allen Poe's reasoning in A Few Words On Secret Writing, I can now place five letters in the correct position within the 13 character code, albeit not to my complete satisfaction.  

Here is a section of reasoning from Edgar Allen Poe's A Few Words On Secret Writing where A can represent N and vice versa, where B can represent O and vice versa, and where C can represent P and vice versa. But he also makes a point of saying A might stand for P (or vice vera). This is where I shall jump into the code using a trial and error approach. 

If A can stand for P, I shall place P above the A in the beginning of the Z13 code like so:

If A can stand for P, and P can also represent C, then A can also stand for C. So let us insert the letter C above A in the Z13 code.

If A can represent N and vice versa, B can represent O and vice versa, and C can represent P and vice versa, then E can represented R. So let us place R in the Z13 code.

Edgar Allen Poe stated that N can represent A, so let us place A above the second N in the Z13 code:

If A can stand for P, and P can also represent C, then A can also stand for C. This means that if M can stand for X, and X can represent K, then M can also stand for K (just like A stood for C). So let us insert K into the Z13 code:

If the K and M between the three eights are representative of themselves as I have previously surmised, then we have the beginning of the answer to the Z13 code. But without this assumption, we have five letters inserted that mirror the previous solution I have suggested - all reasoned from Edgar Allen Poe's essay. It's not perfect, but it's a start.

On October 22nd 1969, the San Francisco Examiner newspaper published an article by Will Stevens, which laid down a challenge from Professor D.C.B. Marsh of the American Cryptogram Association (ACA) to the Zodiac Killer, attempting to coax him into revealing 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".

Professor D.C.B. Marsh was probably hoping the Zodiac Killer would employ a cryptographic technique featured in the works of Edgar Allan Poe, thereby making any future cipher mailed by the Zodiac Killer easier to crack. As it turned out, the Zodiac Killer's 340 cipher mailed on November 8th 1969 could be solved using the scytale method of encryption detailed in Edgar Allan Poe's essay A Few Words on Secret Writing in the very first paragraph. This was covered extensively in the article The Inspiration Behind the Zodiac Killer's 340 Cipher. We have Professor D.C.B. Marsh of the American Cryptogram Association creating the trigger, by inserting Edgar Allan Poe into the mind of the Zodiac Killer. The Zodiac Killer then created the 340 cipher that could be deciphered using the scytale method featured in Poe's A Few Words on Secret Writing. What are the odds that one of Edgar Allan Poe's poems would partially appear in the solution to the 340 cipher?

I HOPE YOU ARE HAVING LOTS OF FUN IN TRYING TO CATCH ME - THAT WASN’T ME ON THE TV SHOW - WHICH BRINGS UP A POINT ABOUT ME - I AM NOT AFRAID OF THE GAS CHAMBER BECAUSE IT WILL SEND ME TO PARADICE ALL THE SOONER BECAUSE I NOW HAVE ENOUGH SLAVES TO WORK FOR ME WHERE EVERYONE ELSE HAS NOTHING WHEN THEY REACH PARADICE - SO THEY ARE AFRAID OF DEATH - I AM NOT AFRAID BECAUSE I KNOW THAT MY NEW LIFE IS LIFE WILL BE AN EASY ONE IN PARADICE DEATH.   

"To One in Paradise" was written by Edgar Allan Poe. This poem was first published as part of the short story titled "The Visionary" (later retitled as "The Assignation"). The poem was also published under the names "To lanthe in Heaven" and "To One Beloved". The title "To One in Paradise" was used in the February 25, 1843 Saturday Musuem. This poem was written after the death of Poe's wife. He writes that she was his life and he lived for her and now he looks forward to the future where they will be together again in death. link.

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.

Just over two weeks before the 340 cipher was mailed, Dr. D.C.B. Marsh of the American Cryptogram Association laid down a challenge to the Zodiac in the newspapers to reveal his name in a cipher, however complicated. The wording in the San Francisco Examiner on October 22nd 1969 invoked the name of Edgar Allan Poe, so possibly the designers of the article were hoping that the Zodiac Killer would invoke Edgar Allan Poe to give us his name, making any offering easier to crack. This appeared to influence the Zodiac Killer, because the first cipher mentioned in Poe's essay A Few Words on Secret Writing actually works in decoding the message in the 340 cipher. The second cipher technique in Poe's essay A Few Words on Secret Writing split the alphabet into two portions of 13 letters, so it was surprising that the Zodiac Killer's next code reduced dramatically to 13 characters just like Poe's design (beginning with A and ending with M). See here for essay.

Three years ago, it was suggested that the Zodiac Killer wouldn't again shy away from the challenge of giving us his name, having possibly given us it in an abbreviated format. That is why the cryptic reference of Fk, I'm crackproof caught my eye in the October 5th 1970 communication with 13 punch-holes in the fabric of the card. The punch-holes were separated into a 10 to 3 configuration, positioned in such a way that they mirrored the design of the 13-Symbol cipher. The only way to break the small code was to discover the entry point, and the three circled 8's seemed as good a place as any, especially when we consider Fk, I'm crackproof is split into three parts and fits around the existing K and M in the code. The crosshairs, anchor and Celtic Cross in the code are all religious symbols, with the number 8 representing rebirth, regeneration and a new beginning in Christianity. The figure 888 is also representative of Jesus Christ in Christian numerology. It was discovered that the first 8 began FK, the second 8 began IM and the third 8 began CRACKPROOF, which completed the circle of eternal life. The introduction to the April 20th 1970 letter was also completed, 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",

Anyway, this is to show that the Fk, I'm crackproof solution was found before the 340 cipher was cracked by Dave Oranchak, Sam Blake and Jarl Van Eycke on December 3rd 2020, along with its scytale links to Edgar Allan Poe's A Few Words on Secret Writing. This is extremely important when we consider the following. Edgar Allan Poe highlighted certain encipherment techniques in the essay regarding a split alphabet, which are outlined here: and, so placed, a might stand for n and n for a, o for b and b for o, &c. &c. This, again, having an air of regularity which might be fathomed, the key alphabet might be constructed absolutely at random. The next line was: Thus A might stand for P.

These examples can be summarized as;
[1] a might stand for n and n for a
[2] Therefore, r might stand for e and e for r
[3] Thus, a might stand for p (and vice-versa)
Using only these examples in the 13-Symbol cipher, I inserted the possibilities into the code, using the letters K and M as entry points, based on the aforementioned reasoning. The letters N, A and M (not boxed in blue) I have no explanation for. So the search goes on to discover whether the Zodiac applied something else to the encryption. Or whether a different technique was used entirely.

When you take into consideration that the Fk, I'm crackproof solution was suggested in 2017, before the scytale link of the 340 cipher to Edgar Allan Poe, coupled with the formation above using just Poe's examples shown in [1], [2] and [3], it shows a pattern receptive to the remaining letters in the solution. But the three remaining ciphertext characters would need explaining. 

The next encipherment technique described in A Few Words on Secret Writing were the two concentric circles (one fixed), where the outer wheel can be rotated around the inner wheel during the coding process. Here is a working cipher wheel.

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. This involved placing the alphabet into the following configuration.

Here is an excerpt from Edgar Allan Poe's A Few Words on Secret Writing: and, so placed, a might stand for n and n for a, o for b and b for o, &c. &c. This, again, having an air of regularity which might be fathomed, the key alphabet might be constructed absolutely at random. The next line was: Thus A might stand for P.

If we then represent the second ciphertext character N (11th position} with the plaintext character A shown in Poe's writing, we get the diagram shown below, with the circular Fk, I'm crackproof starting to emerge.

The relationship  between the remaining ciphertext characters of N, A and M, to the plaintext characters in the solution of O, C and K respectively, can be seen in the diagram below. These are never more than two apart in the alphabet. This is a work in progress.

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.

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?

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

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".