Professor D.C.B. Marsh, in the October 22nd 1969 San Francisco Examiner newspaper article by Will Stevens, 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". It is highly unlikely the Zodiac Killer would have been suckered into providing a genuine cipher of any length knowing that 'any cipher created by man can be solved by man'. The 13 and 32 symbol ciphers mailed in 1970 proved this very fact - both effectively crackproof without a recognizable key. However, the Zodiac could certainly have sent us a rudimentary message within the 340 cipher utilizing the wording contained within his 408 cipher.

Paradice and slaves is a well-trodden theme in the Zodiac communications, and as I have stated before, the Halloween card mailed on October 27th 1970 (almost the anniversary of the D.C.B. Marsh challenge) actually admitted that the 340 cipher was "sorry no cipher". The Zodiac Killer had never apologized previously for not sending a cipher in his 'cipherless' communications, so why start now. Even if the "sorry no cipher" writing on the envelope inner was to inform us that in about two seconds we had no cipher, then just write "sorry no cipher" once. The fact it was fashioned into a cross formation that mimicked the paradice and slaves configuration on the card inner, seemed designed to suggest that this configuration would be found in a cipher that effectively had no solution. The sheer fact that this configuration can also be found in his 340 cipher, exactly bisecting the cipher vertically and horizontally (17 by 17), one would like to believe is a convincing argument to suggest that the Zodiac Killer was finally admitting the 340 cipher wasn't a cipher at all. Additionally, it did mimic the 408 cipher with its inclusion of the paradice and slaves reference. Although this may be interesting, it understandably isn't enough to convince certain quarters of the Zodiac community who are steadfast in their belief that the 340 cipher contains a cogent but elusive message. Regardless, one couldn't help thinking that this wasn't the only time the Zodiac admitted the 340 cipher was devoid of any meaningful solution. Fortunately, the answer came in the communication prior to the Halloween card.  

If I am correct, and the paradice and slaves (13 letters) configuration was intentional in the design of the 340 cipher, then this is a significant point of interest. Two other notable features stand out in the 340 cipher. Firstly, the corrected sixth line where the Zodiac Killer blacks out a forward K and replaces it with a backward K. Secondly, the distinct possibility that he placed his pseudonym on the final line of the 340 cipher. All these three features are present in the '13 Hole' postcard.

Despite the fact that Zodiac made many spelling errors in his design of the 408 cipher and his communications as a whole, he seemed conscientious enough to correct one character in his 340 cipher, that inevitably would have made no difference in it being deciphered, had it contained a genuine solution. The fact he spoiled an otherwise neat and tidy presentation appeared designed to convince us that it was a genuine cipher. After all, why would Zodiac correct a collection of gibberish, if not to convince us it wasn't. The correction seemed contrived in order to validate the authenticity of the cipher, to which he would allude to in the '13 Hole' postcard.        

Many have speculated on why the Zodiac Killer reversed the bottom section of text on the '13 Hole' postcard. He certainly didn't do this for absolutely no reason, as he didn't create the "sorry no cipher" configuration for no reason either. The Zodiac Killer pasted the lettering "Fk I'm crackproof" on the '13 Hole' postcard in a first attempt at showing us the 340 cipher had no solution. The definition of crack-proof is something that is unable to be cracked, or in the case of a cipher, unable to be decoded. He used this word in his April 20th 1970 letter, sarcastically stating "This is the Zodiac speaking. By the way have you cracked the last cipher I sent you". He knew only too well that it hadn't been cracked, because it couldn't be cracked - and now was telling us it was crackproof by association to himself.

The Fk has been suggested as a shortened expletive or possibly a name - but what if we take it on face value, and the Fk actually means Fk and nothing more. It is like Ronseal and 'does exactly what it says on the tin'. The Zodiac Killer is essentially telling us that the corrected Fk on the 340 cipher was a ruse, because his cipher was crackproof. This is why the text on the '13 Hole' postcard is reversed, exactly the same as the reversed K on the 340 cipher. The K on the 340 cipher is not only reversed, but it is now much smaller than all the other characters on the 340 cipher, which is why the Zodiac Killer pastes "Fk I'm crackproof" rather than "FK I'm crackproof". ​ Crackproof, Fk and the reversal of text on the '13 Hole' postcard, coupled with the cross design of 13 (paradice and slaves), inevitably leads back to the 340 cipher. Either that, or he pasted "Fk I'm crackproof" upside down on the '13 Hole' postcard for no reason whatsoever.

What we effectively have, are two consecutive October 1970 communications stating ​"Fk I'm crackproof" and "sorry no cipher", both furnished with a cross design that mimics the appearance of paradice and slaves on the 340 cipher. It is my contention that the Zodiac Killer responded to the challenge of Professor D.C.B. Marsh, but he simply wasn't going to abide by the rules laid down by the cryptography expert, yet he stayed true to the paradice and slaves message in the 408 cipher, albeit in his own inimitable style. The paradice and slaves design in the 340 cipher (extending 17 rows down) still leaves the tantalizing prospect of three 'vacant' rows comprising of 51 unobstructed characters, that may harbor a second puzzle or message. With the Zodiac pseudonym almost appearing toward the end of the cipher, there may be a twist in the tail yet.       

There is a significant number of people who believe the Lake Berryessa attack on Bryan Hartnell and Cecelia Shepard was not the Zodiac Killer, rather an impostor or fraud masquerading as the Bay Area murderer. Despite the overwhelming evidence this attack was by the hand of the Zodiac Killer, the ever grandiose theories of a copycat or 'newspaper driven' conspiracy keep filling the message boards. If you believe the Lake Berryessa murderer was an impostor, then it is reasonable to assume that you also believe the October 27th 1970 'Halloween' card was the same impostor. The murderer of Cecelia Shepard wrote on the car door of Bryan Hartnell's vehicle, finishing his message with the immortal words "by knife". This phrase was withheld from the newspapers and wasn't known by the time the 'Halloween' card was mailed. Since the author of the 'Halloween' card wrote the phrase "by knife" within his communication and selected imagery of a an eye peering from behind a tree with the additional phrase "peek-a-boo you are doomed", it seems rather logical that the author is referring to Lake Berryessa and his escapade of vanishing behind a tree, before reemerging in his masked costume. Unless of course, he just guessed the phrase "by knife" withheld from the newspapers, by simultaneously discovering a Tim Holt comic book with the exact phrase around a death wheel. This impostor is rather a lucky chap.

​This impostor would then discover the workings of the unbroken 340 cipher, writing "sorry no cipher" on the envelope inner of the 'Halloween' card, despite the fact (to our knowledge) that nobody at this juncture had noticed that the paradice and slaves configuration on the card was also present on the 340 cipher, bisecting it at its center both horizontally and vertically. Not only had this impostor accidentally stumbled across the withheld "by knife" in the Tim Holt comic book, but he had also told us the puzzle contained in the 340 cipher. By writing "sorry no cipher" in the same style as paradice and slaves, he was effectively linking the two and stating that the unbroken 340 character cipher contained the configuration paradice and slaves within its design. It was therefore no cipher.

This links the apparent impostor to the Lake Berryessa attack, the 'Halloween' card and the 340 cipher. It is rather amazing that the impostor not only found the hidden "by knife" on the car door by inadvertently thumbing through his comic book collection just prior to the 'Halloween' card, but he found it around a death wheel that he could conveniently transfer and place it around the paradice and slaves configuration on the card. Even more fortunate, was the real Zodiac Killer had apparently allowed the option of paradice and slaves within the design of the 340 cipher, placing the word "by" accidentally in all four quadrants to equally mimic the 'Halloween' card. It is rather more logical to conclude that the designer of the 'Halloween' card also designed the 340 cipher - and because of "by knife", was the perpetrator of the September 27th 1969 Lake Berryessa attack. If you believe the Lake Berryessa attack was an impostor and not Zodiac, then by extension you have to believe the designer of the 340 cipher was the same impostor. 

​If the impostor created the 340 cipher, then he mailed the 'Bus Bomb' letter also. The 'Bus Bomb' communication was mailed in tandem with the 340 cipher and contained the same victim count of 7 in the passage "This is the Zodiac speaking up to the end of Oct I have killed 7 people". It also contained "Oct" in the same fashion as the writing on the 'Dripping Pen' card. Most people are in agreement that the 340 cipher/'Dripping Pen' card and 'Bus Bomb' letter were mailed by the same author. But if an impostor created the 340 cipher, he also sent the 'Bus Bomb' letter containing a piece of Paul Stine's blooded shirt from the October 11th 1969 taxicab murder. By extension therefore, the impostor must be responsible for the murder of Paul Stine and the October 13th 1969 letter. Furthermore, he must be responsible for the December 20th 1969 'Melvin Belli' letter, which also contained a swatch of Paul Stine's shirt. The bottom line being that, if you believe the Lake Berryessa attack to be an impostor, then you have to believe the Paul Stine murder wasn't Zodiac either, along with five other communications that include the October 13th 1969 mailing, the 340 cipher and 'Bus Bomb' letters, the 'Melvin Belli' letter and finally the 'Halloween' card. You cannot have one without the others. The logical conclusion is that the entirety were mailed by the Zodiac Killer, who was responsible for four attacks in the Bay Area. But no doubt, this will be far too boring a conclusion, in a case where facts seem to no longer matter anymore.

The 408 cipher, mailed in three parts to the San Francisco Chronicle, San Francisco Examiner and Vallejo Times-Herald on July 31st 1969 had 18 unsolved characters at its foot. However, the Zodiac Killer likely made an error when transferring his original message into the encrypted version, accidentally omitting the word "people" from the section of code mailed to the San Francisco Chronicle: "The best part of it is that when I die I will be reborn in paradice and all the (people) I have killed will become my slaves". Had he transferred the message correctly, the intended version would have had only 12 unsolved characters in which his identity may have resided, such as "I am the Zodiac". After all, he promised us his identity not his name. What are the chances the Zodiac Killer left a similar message at the foot of the 340 cipher?

Professor D.C.B. Marsh, in the October 22nd 1969 San Francisco Examiner newspaper article by Will Stevens, 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". It was speculated that the Zodiac Killer certainly wasn't going to provide another conventional cryptogram to be easily decoded, so instead created the appearance of a cryptogram with hidden "puzzles" contained within it, such as "paradice" and "slaves" running vertically and horizontally across its mid-section. This was later revealed in the 'Halloween' card, where the Zodiac Killer belatedly informed us the 340 code was "sorry no cipher" and placed "paradice" and "slaves" in a cross formation to point us in the right direction.   

The "sorry no cipher" section of the 'Halloween' card has one section running from bottom to top. The '13 Hole' postcard mailed before this offering has "Fk I'm crackproof" flipped upside down. This gave rise to the idea that the 340 cipher needed to flipped vertically, which I was able to do on Dave Oranchak's excellent Webtoy on the Zodiac Killer Ciphers website. 

​When Professor D.C.B. Marsh laid down the challenge to Zodiac, it was initially considered that the message at the foot of the 340 cipher may have teased the American Cryptogram Association with something like "next time I will tell you who the Zodiac is", bearing in mind where the near-pseudonym was placed. Then, five months later he would follow this up with the reveal of his name, which he effectively teased us with by stating "This is the Zodiac speaking. By the way have you cracked the last cipher I sent you. My name is...."  

This statement is very telling, when we consider that it was patently obvious that his last cipher hadn't been solved - so why did he add this to the opening of the April 20th 1970 communication? The final section of the 340 cipher may explain why he began this correspondence in the way he did. It may be conceivable that the last section of the 340 cipher promised to reveal his name in the next cipher, hence the blatantly obvious introduction in the April 20th 1970 communication, of "This is the Zodiac speaking. By the way have you cracked the last cipher I sent you. My name is...."  We effectively have to bridge the gap between "I am the Zodiac" (if correct) on the 408 cipher to "My name is" on the April 20th letter. The obvious connector would be the promise of a new cipher or code containing the Zodiac Killer's name. 

It is notable that the 340 cipher begins with "her" (the last three letters of cipher), however, it is impossible to form the word "cipher" in the format offered. The uniform 17 X 20 pattern of the cipher would be broken by adding "cip" to the beginning. For this section to provide us with the word "cipher" within the existing pattern and the promise of a new cipher containing the Zodiac's name, the 340 cipher has to be flipped - possibly as the 'Halloween' card and '13 Hole' postcard had hinted nearly a year later. Other than the 408 cipher mailings, every other Zodiac correspondence began with the introduction of "This is the Zodiac Speaking". The 340 cipher, when flipped, enables this introduction to begin the 340 character message also. ​ 

But what is the likely message encoded at the foot of the cipher? Without having decoded it, I can only make a calculated guess from other Zodiac correspondence. In the August 4th 1969 'Debut of Zodiac' letter, the killer wrote "By the way, are the police having a good time with the code? If not, tell them to cheer up; when they do crack it, they will have me".  

In the April 20th 1970 communication, the killer wrote "By the way have you cracked the last cipher I sent you. My name is...." 

Therefore, I will use the literal words of the Zodiac Killer to complete the last 27 characters of the 340 cipher, obviously changing "last" to "next".
​
By flipping the 340 cipher vertically we are able to use the clue of "Zodiac" to generate his usual introduction and then form the bridge between cipher one and cipher three with the promise of his name in cipher two, using the words of the Zodiac Killer himself. Whether this analysis has any semblance of truth is another matter entirely. 

Luis Campos, born in Santiago, Dominican Republic is an inventor, poet and cryptographer who created puzzles and ciphers for the United Features Syndicate of New York, beginning in 1983. He would create six celebrity ciphers a week, featuring famous quotes from well-known people, past and present. The reader had to identify the person and quote from the encoded text. The characters in the cryptograms were deliberately spaced into separate words, as shown on the right. 

On September 25th 1990 somebody mailed the celebrity cypher to the Vallejo Times-Herald, approximately three months before the 1990 'Eureka' card, often associated with the Zodiac Killer. Bearing in mind the 408 cipher mailed to the San Francisco Chronicle, San Francisco Examiner and Vallejo Times-Herald on July 31st 1969, many have pondered whether this postcard was mailed by the Bay Area murderer. There is little to prove this notion one way or another, but if somebody was mimicking the Zodiac Killer, one might expect the wording on the card to equally mimic previous correspondence, in particular, phrases he used with respect to his codes and ciphers. 

Many people have put forward solutions to the celebrity cypher, including the website Zodiologists.com and Rubislaw32 (a regular contributor to this site). Some of these solutions can be found on Ricardo Gomez's Project MK-Zodiac site. But here, I am not going to tackle the celebrity cypher from the angle of cryptology, because not only do I have a basic knowledge of ciphers, but also, the mere fact that so many people of greater ability than me have come to wildly different conclusions, is evidence of a code that is malleable. In other words, this code is open to subjective interpretation and no solution, despite the belief of the code-cracker, has been universally accepted. Of course, nobody knows, or could know with certainty, who the author of this postcard is. However, if the author mailed a cipher to the Vallejo Times-Herald in an attempt to pass this communication off under the guise of Zodiac-style correspondence, could it be argued that the sender is also a murderer? One attempted solution caught my eye on the Zodiac Killer Site forum - and this is the path I will follow, despite the pitfall of characters being hidden behind the stamp. Here is the card, on which I have added some notations which will be explained later.   ​ 

​The first thing to notice is that the author likely places his name and address on the upper left hand side of the celebrity cypher, and also signs off the card with his name. Often a sender will provide a return address on the left side of a postcard or envelope. This is backed up by the identical thirteen characters beginning and ending the correspondence. Then we have to predict what the preceding text is before the author signs off with their name. On the left is the '13 Symbol' cipher mailed by the Zodiac Killer on April 20th 1970. He precedes the code or name with My name is. 

In the Luis Campos example at the top of the page, the final line is reserved for the name. Therefore, it makes perfect sense that the Zodiac Killer or somebody imitating him, would write My name is before signing off with their name. This may be preceded by a question, such as "Do you know me", in view of the Bay Area murderer having committed his crimes just under 21 years ago. A variation of do you remember me? Even if the author wasn't the Zodiac Killer, they may have been projecting the idea that they were. 

The next thing to look at is the return address. It has 10 characters followed by seven, then two. Many on the Zodiac Killer forum have deduced that the bottom line of the return address to be Oakland, CA - so I will run with this idea. The postcard was postmarked Oakland, so it's reasonable to conclude the return address would be Oakland too. This being the case, the 10 characters above must represent the area within Oakland. Now comes the simple task of finding a potential murderer who possibly authored this postcard. Somebody who knew of the Zodiac Killer, lived in an area of Oakland (comprised of 10 letters), and was eventually caught and convicted of murder. Surprisingly, if you type into Google search "Oakland, murderer, 1990" a possible answer is served up on a plate. Somebody who certainly lived in Oakland up to 1992, murdered two women in Oakland Hills that year, and lived with his grandparents near to Skyline Road and Golf Links Road, the deposition site of the two murdered women. Where exactly his grandparents lived, I have yet to ascertain, but there is a 10-letter neighborhood in East Oakland called Castlemont. It is less than a mile from Golf Links Road. His name was Monte Crawford, exactly fitting the 5 and 8 characters at the foot of the celebrity cypher.   

Monte Crawford, a military veteran, was sentenced on Friday, August 1st 2014 to 40 years to life for the 1992 double murder of Tredis Penny (26) and Shirley Wynn (38), both strangled and sexually assaulted, before being dumped in the Oakland Hills. I have no idea whatsoever if Monte Crawford was responsible for the celebrity cypher, but he did live in Oakland, in or near Castlemont, both of which fit the code, and he was capable of murder as he showed just one and a half years later, if he wasn't already a killer at this juncture.   

It is no coincidence that the Zodiac Killer only wrote "in this cipher is my idenity" in the letter he mailed to the San Francisco Chronicle on July 31st 1969, because this one-third of the cipher contained the 18 unsolved characters at its foot. This was also the only letter of the three to begin with "This is the murderer". The other two communications to the San Francisco Examiner and Vallejo Times-Herald began with "I am the killer". This shift in introduction may be completely accidental, may be subconscious or may be completely deliberate on account of the "identity" he is to place at the foot of the cipher. The author of these three communications had deliberately separated them into three parts, and therefore when he was preparing the San Francisco Chronicle letter, one would like to think he was considering the opening line when placing his identity at the end of the cipher. If he was ever going to disclose his identity (but not his name), then logically it would be an extension of "I am the killer" to "I am the Zodiac Killer", and therefore satisfy the quota of 18 unsolved characters required by the cipher. I have inserted "I am the Zodiac Killer" at the end of the opening lines of the San Francisco Chronicle and San Francisco Examiner to show how the revelation of his identity in the Chronicle better suits the introduction of "This is the murderer". 
San Francisco Chronicle: "Dear Editor, This is the murderer of the 2 teenagers last Christmass at Lake Herman + the girl on the 4th of July near the golf course in Vallejo. I am the Zodiac Killer" 
San Francisco Examiner: Dear Editor, I am the killer of the 2 teen-agers last Christmass at Lake Herman and the Girl last 4th of July. I am the Zodiac Killer"     

The Zodiac Killer may have accidentally dropped the word "people" from the San Francisco Chronicle cipher (shown in red above) when he transitioned from one cipher to another, unwittingly missing out this word from his original draft to final version, and thereby forcing him to switch from the intended 12 characters he meant to leave, to a revised 18 characters.To rectify his mistake he simply changed "I am the Zodiac" to "I am the Zodiac Killer". The confirmed murderer of five never used the term "Zodiac Killer" in any of his subsequent communications, opting for "This is the Zodiac speaking", but may have had his hand forced on this occasion. It would have been relatively easy to just rewrite the San Francisco Chronicle cipher, but this was an easy solution. One can see how the Zodiac Killer chose his words in the October 13th 1969 letter, opening up with "This is the Zodiac speaking. I am the murderer of the taxi driver over by Washington St + Maple St last night". He uses the words "I am" because he has already introduced himself as the Zodiac. In the July 31st 1969 San Francisco Chronicle letter he uses the words "This is the murderer" because he has thus far failed to introduce himself, which he reserves for the final line of the cipher, stating "I am the Zodiac (Killer)". It is effectively a reversal of the Paul Stine letter. 
Paul Stine letter: "This is the Zodiac speaking. I am the murderer of the taxi driver".  
San Francisco Chronicle: "This is the murderer of the 2 teenagers. I am the Zodiac Killer"    

The murderer would very quickly introduce himself in the August 4th 1969 'Debut of Zodiac' letter: "This is the Zodiac speaking. In answer to your asking for more details about the good times I have had in Vallejo, I shall be very happy to supply even more material. By the way, are the police having a good time with the code? If not, tell them to cheer up; when they do crack it, they will have me". He was introducing himself as "Zodiac", so when the police did eventually crack the code, in effect, they would have "had Zodiac". 

An anonymous caller in San Francisco declared that whoever devised the code "would have to have a vast knowledge in three fields - surveying, nautical science and marksmanship". How the caller could derive that the triple murderer had a vast knowledge of marksmanship from these attacks is hard to justify, not to mention nautical science and surveying. Was the Zodiac Killer ringing the police and blowing his own trumpet? The murderer did ultimately commit his murders with varied weaponry and did eventually introduce a map and radians into his communications.   

If we are looking for an identity or pseudonym in the 18 unsolved characters of the 408 cipher, then it must include appropriate word usage in order to increase the originally intended 12 characters up to 18 characters. So if the original message was "I am the Zodiac" or "Zodiac Killer", then the author had to supplement it with an extra 6 characters to replace the word "people". The simplest avenue available was to add "Killer" or "I am the", in order to generate these 6 characters. These were all used consecutively in two of the three communications mailed on July 31st 1969, when the Zodiac Killer wrote "I am the killer of the 2 teenagers last Christmass at Lake Herman + the girl last 4th of July" to the San Francisco Examiner and Vallejo Times-Herald.  

The Zodiac Killer had seemingly failed to fully convince Vallejo Police Chief Jack E Stiltz, who was less than satisfied that the letter writer and killer were one and the same, urging the author of the July 31st 1969 letters to send in more details of the crimes. The Zodiac Killer immediately dispatched the 'Debut of Zodiac' letter on August 4th 1969 with the introduction of "This is the Zodiac speaking". Although the Zodiac Killer could add more details of the crimes in this new letter to prove he was the killer, It is conceivable he revealed his pseudonym after only four days to inextricably link himself to the first three letters. The only way he could achieve this beyond any doubt, was to reveal a significant word in the unsolved cipher. Then the police would know for certain when the code was broken, that the author of the August 4th 1969 letter was not only the killer, but the designer of the cryptogram. So he introduced his pseudonym "Zodiac" earlier than he had originally intended and immediately rushed it off to the San Francisco Examiner newspaper on August 4th 1969, before the cryptogram was solved.

​Remember, if Vallejo Police Chief Jack E. Stiltz had not urged the author of the July 31st 1969 letters to send in more details to prove the letter writer was the killer, the 'Debut of Zodiac' letter would likely never have been written and sent to the Examiner. The "Zodiac" would still have been the "killer" by the time of the Paul Stine murder. He revealed his pseudonym to link himself to the San Francisco Chronicle's 18 characters, but unfortunately for him, he clearly underestimated the difficulty of the encryption. The release of his identity or pseudonym "Zodiac" so quickly, may lend credence to its presence in the remainder of the 408 cipher, and by extension, the 18 unsolved characters harboring a genuine and coherent message. 

​"This is the Zodiac speaking. By the way, are the police having a good time with the code? If not, tell them to cheer up; when they do crack it, they will have me".

THE 18 UNSOLVED CHARACTERS [PT1]
THE 18 UNSOLVED CHARACTERS [PT2]
​THE 18 UNSOLVED CHARACTERS [PT3]

In the last article 'The 340 Cipher-Trick or Treat?' we attempted to show how the Zodiac Killer used two xeroxed keys in the 1990 'American Greetings' card to intimate that the 340 cipher should be inverted or flipped, in order to begin the message with 'This is the Zodiac speaking'. The 'Halloween' card intersecting "sorry no cipher" key, was also used to show how Paradice and Slaves was pivotal to the design of the 340 cipher. But another cryptic communication arrived just 22 days before the 'Halloween' card, on October 5th 1970, entitled the '13 Hole' postcard. The Zodiac Killer could easily have drawn or photographed the keys in the 'American Greetings' card, but opted to xerox or photocopy them. The same could be said of "sorry no cipher", which he could easily have written once. This led to the notion that these two deliberate choices had a meaning or message. This brings us to the '13 Hole' postcard.

Just like the 'American Greetings' card, why does the Zodiac Killer punch 13 holes through the fabric of this card in a 10:3 configuration, rather than just fill in 13 circles like his ciphers? On the address side these holes can be found on the extreme left of the card, which then obviously switch position when the card is turned over. It can also be noted that the text at the bottom left of the card is also flipped over. It read ​"There are reports city police pig cops are closeing in on me. Fk I'm crackproof. What is the price tag now?" The 'American Greetings' card, it was suggested, used two keys to infer the 340 cipher code should be flipped - the bottom row becoming the top row and vice versa - allowing one of only two prominent 'words' on the 340 to settle on the top row, to facilitate the opening message of 'This is the Zodiac speaking'. The second prominent word of 'Her' (that begins the cipher) would now be flipped to the bottom line of the 340. The '13 Hole' postcard gives us the first clue to suggest the likelihood of this being the case.

The Zodiac Killer punched 13 holes into the card with a hole punch, A keypunch is also a device for precisely punching holes into stiff paper cards at specific locations as determined by keys struck by a human operator. Or in computing, a mechanical device whose keys are pressed, individually or in combination, to punch holes in punched cards or paper tape that correspond to particular characters. Programs or wording can be encoded onto a punched card. Did the Zodiac Killer encode a message in a 10:3 configuration using these punched holes, that would not only take 'Her' to the bottom line of the 340 cipher, but use the identical wording on the envelope of the 'Halloween' card to achieve it?    

The message the Zodiac Killer may have wanted to convey, was that "sorry no cipher" hypothetically written on the address side of the '13 Hole' postcard, would not only separate the word 'Her', but it would effectively be inverted or flipped over to the other side when the postcard was turned. The flipped text containing "Fk I'm crackproof" testament to the fact we have a 'Flipped key', despite the boast of Zodiac claiming he was "crackproof" because of it  The 'Her' has now switched sides, thereby giving us our third key to the workings of the 340 cipher. The Zodiac Killer used two keys in the 'American Greetings' card to flip the 340 cipher, and a hole punch here to project the same message. He even added a red crucifix with the number 13 above, to highlight the connection to the 'big thirteen' letters of paradice and slaves on the 'Halloween' card he was soon to mail. Inversion was at the heart of these three communications, using keys in all instances - and all pointing to a 340 cipher that should be turned on its head. 

The first section of this article is a refresher, before we incorporate the rarely mentioned 'American Greetings' card, postmarked December 1990. This card, devoid of any handwriting on the card inner, was the sister communication to the Halloween card, also beginning with "From your secret pal", but contained a photocopy or xerox of two keys that have mystified as to their meaning. We will attempt to combine this communication with the Halloween card and explain its relevance to the Zodiac Killer's unsolved 340 cipher. As always, this analysis must be treated with a healthy dose of skepticism.
  
So firstly, I would like to press home the notion that the Zodiac Killer's 340 cipher was nothing more than a ruse, designed to stick two fingers up to the challenge laid down by Professor D.C.B. Marsh of the American Cryptogram Association (ACA) on October 22nd 1969, when he "invited Zodiac to send The American Cryptogram Association a cipher code - however complicated - which will truly and honestly include his name." The Zodiac Killer would eventually reveal the workings of the 340 cipher just over a year later when he mailed the rather cryptic Halloween card on October 27th 1970, revealing the trick, not treat, he had perpetrated on his challengers. The killer couldn't have been any more obvious when he actually wrote "sorry no cipher" on the envelope inner.

​In 1970, the Zodiac Killer mailed the Dragon card, the Kathleen Johns letter, the Little List letter and the '13 Hole' postcard, none of which stated the glaringly obvious, that he hadn't sent a cipher with any of them. Why would he then apologize for not sending a cipher with the Halloween card when it was patently apparent upon opening the communication? Even if he had wanted to apologize, why didn't the Zodiac Killer just write "sorry no cipher"? The fact he wrote it twice in the form of two intersecting lines suggests this design was created for a purpose. The only other intersecting text on the entire card were the words "Paradice" and "Slaves", so was the author of the Halloween card telling us that something he had created wasn't a cipher, only the intersecting words of "Paradice" and "Slaves"? If we could find "Paradice" and "Slaves" intersecting each other in any previously unsolved cipher, structured in similar fashion to "sorry no cipher", then this should be a strong argument to the meaning behind the Halloween card. We need to find "Slaves" running horizontally, preferably at the center of the 340 cipher and bisect it with the word "Paradice" (hopefully beginning with the letter "P" somewhere at the top of the cipher along the 9th column). 

Fortunately, nine characters along the top row is the letter "P". Then we must travel downwards 17 characters in order to create two lines of equal length and find the "E" of "Paradice". This will now be represented by the character "<".  We now have two lines of 17 characters, bisected by a "+" sign (the center of the crosshairs). The 'wings' of the crosshairs are represented by two dashes, situated in columns 1 and 17. These represent the two "S" letters of "Slaves". This is all very convenient. 

​There are only two identical characters (the "+" sign) in the 9th column along the first 10 rows, and we know the letter "A" is center of the bisecting "Paradice" and "Slaves" on the Halloween card. It is then a simple task of placing the "R" of "Paradice" and "LV" of "Slaves" into position, to exactly mirror the Halloween card formation. It is then not difficult to find the word "By" in all four quadrants of the 340 cipher, again mirroring the Halloween card. See here for visual. 

The second clue may have also come from the envelope, when the Zodiac Killer underlined the 'LAV' of the misspelled Paul Avery on the address side. The three letters 'LAV' bisected the center point of the 340 cipher. What are the odds of "sorry no cipher" mimicking the "Paradice" and "Slaves" formation on the Halloween card, which then mimicked the 340 cipher, along with  the three alphabetical letters 'LAV' being integral to both. 

The Zodiac Killer knew that the first anniversary of his 340 cipher being unsolved was fast approaching, and this Halloween opportunity of revealing his trick to the world, albeit wrapped in another cryptic message, was simply too much to resist.

The words "Paradice" and "Slaves" were decoded in the 408 cipher and featured prominently in the Halloween card, so what are the chances they were an integral part in the design of the 340 cipher as well? So much so, they may have formed crosshairs, bisecting the cipher at its midpoint? If none of the above was an intentional creation by Zodiac and it all fell out by accident, then he is certainly one hell of a fortunate designer. 

In the words of Thomas Horan, the 340 cipher was certainly the "Great Zodiac Killer Hoax of 1969".

When the Zodiac Killer mailed his trinity of July 31st 1969 communications he withheld his identity or pseudonym, but beginning on August 4th 1969 with his 'Debut of Zodiac' letter through to his March 13th 1971 'Los Angeles' letter, every single letter the Zodiac Killer mailed began with "This is the Zodiac Speaking" (excluding cards). So why should the 340 cipher message be any different - which was effectively a letter within a card. 

We do not know if the Zodiac Killer was responsible for the mailing of the 'American Greetings' card, but for the purpose of this argument we will assume that he was. On the left is the photocopy of the two keys that arrived with the communication. The two keys must have had some meaning to the sender - but what? It is clear that the sender could have photographed the keys, drawn two keys or even pasted two 'newspaper keys' onto the card, but made the deliberate choice of photocopying two keys for a reason. The act of the photocopying, one would like to believe, was done to convey a message.

A negative photocopy inverts the colors of the document when creating a photocopy, resulting in letters that appear white on a black background instead of black on a white background. Negative photocopies of old or faded documents sometimes produce documents which have better focus and are easier to read and study. Wikipedia. ​To invert something is to put upside down or in the opposite position, order, or arrangement. Synonyms of invert, are to turn upside down, upturn, upend, turn around, turn about, turn inside out, turn back to front, reverse, flip (over) or transpose. Therefore, was the designer of the 'American Greetings' card hinting that we should "invert the key" or "flip the key". In other words, the key to the 340 cipher is to "invert" or "flip" it on its head in order to read it. The "sorry no cipher" arrangement on the Halloween card envelope was equated with "Paradice" and "Slaves", but could have been written with the 'vertical' "sorry no cipher" running downwards. Could this imply that "Paradice" was meant to be flipped on the 340 cipher, running from bottom to top?  

If we go to David Oranchak's excellent Zodiac Killer Ciphers website and employ his 340 cipher Webtoy using the 'flip vertically' function, the 20th and 1st rows are flipped, the 19th and 2nd rows are flipped, and so forth. In essence, the bottom line now becomes the top line. The "Zodiac" he gave us on the 20th line is now in the perfect position on the top line to open up this communication or cipher with the infamous words "This is the Zodiac Speaking", just like every other letter from August 1969 to March 1971. 

The correspondence before the Halloween card was the October 5th 1970  '13 Hole' postcard. It too contained a cross and flipped text, stating "There are reports city police pig cops are closeing in on me. Fk I'm crackproof. What is the price tag now?"

Wouldn't it be nice if "Fk" meant "Flipped key" as well, and the '13 Hole' postcard was the third member of the trinity of solutions to the Zodiac Killer's unbreakable 340 cipher.

Thirteen days after the Zodiac Killer mailed the 'Dripping Pen' card and 340 cipher on November 8th 1969, another letter and code purporting to be from the Bay Area murderer was mailed to the San Jose Police Department on November 21st 1969, possibly containing a threat on a "widow" in the San Jose area. Both mailings have so much in common, along with the December 7th and 16th 1969 Fairfield letters, which also contained rudimentary codes. The Zodiac Killer wrote the chronological months of his murders at the foot of the 'Dripping Pen' card: "Des, July, Aug, Sept, Oct = 7". Bearing in mind that all but August were accounted for, it is now clear the card was inferring the murders of two young girls, Deborah Gaye Furlong (14) and Kathy Ann Snoozy (15), who were found savagely stabbed on August 3rd 1969 in the Bay Area of San Jose. It is therefore no surprise that his next communication should be focused on San Jose just two weeks later. Below is part of the FBI file revealing some of its contents.

Placing "November=8" could be viewed as an extension to his "Des, July, Aug, Sept, Oct = 7", indicating he was claiming another murder in November. He also began the communication with familiar words: "There's no doubt I will do my Thing". As the communication was mailed to the San Jose Police Department, we would now have three victims in San Jose to which he was laying claim to. The short code (shown above) was -- + 6 2 + --, containing two dashes either side, two pluses, and the numbers 6 and 2. Both Fairfield letters contained rudimentary codes pertaining to the 340 cipher, as though he was giving us a clue to its design. This may also have been the case when he mailed the Halloween card on October 27th 1970, intersecting the words Paradice and Slaves in a cross formation and writing "sorry no cipher" in similar fashion on the envelope. In fact, the December 16th 1969 Fairfield letter contained a design similar to the Halloween card. The 340 cipher can be shown to accommodate the words Paradice and Slaves, bisecting the cipher horizontally and vertically across its mid-section. This opened up the possibility that the San Jose code was somehow connected to this design. Both Fairfield letters harked back to the 340 cipher, so why not the San Jose code also.  

The symbols contained in the San Jose code exactly mirror the order shown on the horizontal mid-section of the 340 cipher. The 10th line is where some believe the cipher could be divided, along with the possibility of the word Slaves residing. Not only do the dashes and pluses line up exactly with the San Jose code using the mid-section of the 340 cipher, but the numbers 6 and 2 would slot nicely in between. If we used basic number play, and converted 6 to F and 2 to B, both these letters can be found together on the 10th line also. All six characters from the San Jose code present on the Slaves line of the 340 cipher. 

This may very well be coincidence, but with "There's no doubt I will do my Thing", "November=8" and this correspondence immediately following the 'Dripping Pen' card and 340 cipher, one could argue the Zodiac Killer was dropping us hints to the mechanics of his "crackproof" cipher. Something he would again do with the arrival of both Fairfield letters in December.

The Zodiac Killer could wait only one month after the Button letter, to give us further clues regarding the bomb he claimed to have buried, when he wrote "P.S. The Mt. Diablo code concerns Radians + # inches along the radians". Why should the San Jose and Fairfield letters be any different?   

Sometime in 1971 a questionable Zodiac correspondence and cipher was received by the San Francisco Chronicle, postmarked Fairfield, California. This was now the fourth Zodiac related communication mailed from Fairfield, following the December 7th, December 11th and December 16th 1969 trinity. There is limited widespread information regarding this letter available on the internet other than the Zodiologists.com website, who have analyzed this correspondence in great detail. The letter and cipher is to be found using the Wayback Machine on Ed Neil's old website TheZodiacFiles.com. I have cleaned up the letter without altering any of the text by the author:

I'll DO IT TO BECAUSE I DONE IT 21 TIMES. I CAN'T STOP BECAUSE EACH ThAT I KILL MAKES IT WORSE AND I MUST KILL MORE. MAN IS ThE MOST PRIZED GAME. ILL NERVER GIVE MY NAME BECAUSE YOU dONT UNDERSTAND. NEXT TIME I WILL SEND A PATCH OF HUMAN SKIN if their is SOME Left OVER.

The 148 character cipher decodes to:
"Tis the Zodiac Speacking. Why can't you stop me. I can't stop killing. Stop listening t(o) phonys. If this is not on your front page in a week I will skin 3 little kids and make a suit from the skin". 
The wording in the letter "I'll do it to because I done it 21 times" is consistent with a mailing date sometime after the March 13th 1971 'Los Angeles' correspondence from Zodiac, claiming 17+ victims. Using a simple calculation we can estimate how often the Zodiac claimed a victim. From December 20th 1968 to July 26th 1970 Zodiac claimed 13 victims over 584 days. That is one victim every 44.9 days. Therefore, from victim 13 to 21, another 8 victims were claimed (8 X 44.9 = 359 days). Add 359 days to July 26th 1970 and we arrive at July 20th 1971, approximately four months after the 'Los Angeles' letter.

This letter and cipher appears at first glance a dubious Zodiac communication, but as Zodiologists.com point out, how difficult would it be for a hoaxer to mimic the ciphers or crosshairs of Zodiac. The fact the author failed to do this, should be pause for thought. There is also something about this letter that indicates the author had written another 'Zodiac' communication (or the author was the actual Bay Area murderer). The other communication, also mailed to the San Francisco Chronicle on July 13th 1971, mirrored the 148 character cipher and letter in one crucial way - the victim total. The last two widely accepted Zodiac communications were the March 13th 1971 'Los Angeles' letter claiming 17+ victims, and the January 29th 1974 Exorcist letter  claiming 37 victims. The author of the above correspondence had 19 victim totals to choose from (18 to 36), yet he chose 21, the exact total mentioned in the July 13th 1971 'Monticello' card, which featured in the San Francisco Police Department DNA report under "suspected Zodiac correspondence". Did the author of the above correspondence just get lucky, in accidentally choosing 21 victims like the 'Monticello' card, or was he the author of both?

The 'Monticello' card was mailed on July 13th 1971 stating: 
'Near Monticello Shought Victims 21 ...... In The Woods Dies April'.
By my rudimentary calculations the 148 character cipher and letter should have been mailed on July 20th 1971, only one week after the 'Monticello' card. If somebody can find the exact date of mailing regarding the 148 cipher and letter, or when this correspondence was published in the San Francisco Chronicle, it would be of immense value. The 'Monticello' card, by all accounts, was not published in the newspapers. If this were the case, then the victim total of 21, chosen by two independent authors looks extremely unlikely. If the 'Monticello' card was designated as "suspected Zodiac correspondence" by the San Francisco Police Department, then by extension, the above correspondence should be afforded the same value.        

THIS SECTION BELOW HAS NOW BEEN NEGATED BY A FUTURE ARTICLE, SHOWN HERE:

zodiacciphers.com/zodiac-news/the-complete-meaning-behind-the-monticello-card

​Denise Kathleen Anderson (22), who resided in Sacramento, was last seen on April 13th 1971 by her roommates at approximately 05.30 am - and as of writing her disappearance still remains a mystery - although foul play is suspected. What occurred with Denise Kathleen Anderson after last being seen by her roommates is unknown, but her disappearance (and possible murder) again took place in Sacramento, near Interstate 80, only five months after the murder of Carol Beth Hilburn and exactly one month after the Zodiac 'Los Angeles' letter mailed on March 13th 1971, claiming 17+ victims. In this correspondence Zodiac stated "If the Blue Meannies are evere going to catch me, they had best get off their fat asses + do something. Because the longer they fiddle + fart around, the more slaves I will collect for my after life." The question is, was Denise Kathleen Anderson one of them?
She disappeared on April 13th 1971, so the 'Monticello' card (with break added) could be referring to the possible murder of Denise Kathleen Anderson in the woods during April:
'Near Monticello Shought Victims 21 ...... In The Woods.  Dies April'.
The 148 character cipher and letter stating "I'll do it to because I done it 21 times" could very well be confirmation that the victim he sought (possibly Denise Kathleen Anderson) had now been claimed.

What are the chances the 'Monticello' card was also mailed from Fairfield? Denise Kathleen Anderson lived in Sacramento,  only 43 miles from Fairfield - but was she the 21st victim of the Zodiac Killer?  

On October 27th 1970 the Zodiac Killer mailed the Halloween card to the San Francisco Chronicle, stating "sorry no cipher" in the form of a cross, and fashioning "Paradice" and "Slaves" in the same manner. In the four corners he placed By Fire, By Gun, By Rope and By Knife. For anyone who believes the September 27th 1969 Lake Berryessa attack was at the hand of the Zodiac Killer, must surely conclude the "by knife" reference on the Halloween card to be admitting his participation in this crime, as this phrase on the car door had been withheld from the public and newspapers alike. This inextricably links the author of the Halloween card to the Lake Berryessa attack. Elements of the Halloween card can be found in the 340 cipher, with "Paradise" and "Slaves" bisecting the cipher (17 X 17) horizontally and vertically, with the word "by" placed horizontally in each of the four quadrants. 

The Halloween card alliance to the Lake Berryessa attack formed "by knife", in conjunction with the knothole in the tree and the wording "peek-a-boo you are doomed", should leave little doubt the two are connected. There is also a strong connection from the Halloween card to both the December 7th 1969 and December 16th 1969 Fairfield letters, and in turn, all three to the 340 cipher. The December 16th 1969 Fairfield letter contained a crude arrangement of 9 symbols (10 including the large crosshairs), impossible to decode as it stood. The four crosshairs around a larger version looked extremely similar to the Halloween card arrangement - and bearing in mind the December 16th 1969 Fairfield letter was accompanied by a crude drawing of a knife entitled "The Bleeding Knife of Zodiac", it seemed likely the short code may have been Zodiac's initial attempt at revealing the hidden words on the car door of Bryan Hartnell's 1956 white Karmann Ghia. 

Thanks to Tahoe 27's excellent find linking the Halloween card to a Tim Holt comic book, depicting Death By Fire, Death By Gun, Death By Rope and Death By Knife, it seemed obligatory to consider the connection from the Halloween card "by knife" to the "The Bleeding Knife of Zodiac", along with the similarity in design between the Paradice/Slaves arrangement and the four crosshairs circling a larger version. The four methods of death represented by the four crosshairs or targets.   

The Halloween card, 340 cipher and both Fairfield letters seemed intertwined. The fact that Zodiac placed "sorry no cipher" in the form of a cross rather than just singularly, can be linked to "Paradice" and "Slaves", and therefore the 340 cipher. Was he suggesting the 340 cryptogram was not a true cipher? It appeared he may have been dropping clues to the design of the 340 cipher as early as December 7th 1969, placing a 38 character code in the first Fairfield letter.

On the left, "by" can be observed in all four quadrants. Parts of the December 7th 1969 code are highlighted in blue, while four of the adjacent symbols from the December 16th 1969 code are highlighted in yellow.

The December 7th letter opened with the words "I just need help", reminiscent of the December 20th 1969 Melvin Belli letter, and followed by "I will kill again, so expect it any time the will be a cop", similar in fashion to the April 20th 1970 letter, where Zodiac stated "But there is more glory in killing a cop than a cid because a cop can shoot back". The December 16th letter opened with the same two words as the December 7th letter, stating "I just want to tell you", almost certainly tying them together - along with the handwriting and crude coding. Bearing in mind neither of the Fairfield letters appeared in the newspapers, it appears that Zodiac either just accidentally mirrored these communications with the subsequent December 20th 1969 and April 20th 1970 letters, or he was the author of all four.

Was the Paradice, Slaves, By Fire, By Gun, By Rope and By Knife configuration a representation of the number of murders he was intending to secure for the afterlife. Paradice, Slaves, By Fire, By Gun, By Rope and By Knife oddly contained 38 letters. The character count on the December 7th 1969 Fairfield letter code was 38. The intended victims on the December 16th 1969 Fairfield letter was 38. The 340 'Dripping Pen' card, eerily similar to the "Bleeding Knife of Zodiac" depiction, opened with the wording "Sorry I haven't written, but I just washed my pen." This phrase again contained the words "I just", but also an alphanumeric count of 38. The April 20th 1970 letter, stating "I hope you have fun trying to figgure out who I killed" had a code that added up to 38 when the alphabet was placed alongside it.
And finally, the Exorcist letter (widely believed to be the final offering by the Zodiac Killer) claimed 37 victims, but promising to kill again if his demands were not met. Probably coincidence, but curious nonetheless.  

The 'Dripping Pen' card may have been a depiction chosen by the Zodiac Killer regarding his exploits at Lake Berryessa. The pen dripping blood as he is writing on the car door of Bryan Hartnell's vehicle, and his reason for washing it. The 340 cipher accompanying this card, with the "Paradice", "Slaves" and "by knife" link back to the Halloween card, further indicating a connection to Lake Berryessa through these communications. 

​The 'Death By Fire, Death By Gun, Death By Rope and Death By Knife' agenda could have been formed in the mind of the killer as early as the beginning of his campaign of terror, when he mailed the 408 cipher, stating  "the best part of it is that when I die I will be reborn in paradise and all the (people) I have killed will become my slaves. I will not give you my name because you will try to slow down or stop my collecting of slaves for my afterlife". The same paradice and slaves permeating through much of his correspondence, and possibly the 340 cipher also. "By knife" an integral part of both Fairfield letters and the Halloween card, to hopefully lay any doubts to rest, of his involvement and knowledge of the writing at the foot of the message on Bryan Hartnell's car door.

The December 16th 1969 "knife," in a side-by-side comparison to the writing on the car door of Bryan Hartnell. Anyone could have read about the Lake Berryessa attack on Bryan Hartnell and Cecelia Shepard with a knife, but would an impostor have emphasized it in the form of a drawing, as to signify its importance, without knowing for certain the hidden message on the car door? And how would the Zodiac Killer, when designing the Halloween card, accidentally mirror the "death by fire, gun, rope and knife" arrangement on the Fairfield letter, when the December 16th 1969 letter was never published in the newspapers. Somebody attempting to imitate the Zodiac Killer in both December letters, would surely have attempted to imitate him, not go out of their way to undo the neatness and organization exhibited by the 340 cipher and thereby nullify their efforts? The Zodiac Killer would have had no such concerns.

Here I would like to return to an old topic with a fresh approach, partly inspired by 'Nobody,' a regular contributor to this site.
As early as August 10th 1969 Professor D.C.B. Marsh of the American Cryptogram Association (ACA) was commenting on the Zodiac ciphers. In the San Francisco Sunday Examiner & Chronicle he praised Donald Harden's deciphering skills and called the code "complicated and obviously drawn by somebody who knows his business". 
​
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." 

Clearly, Dr. Marsh and the detectives would have considered it highly unlikely for the Zodiac Killer to respond by giving us his name, but while he was constructing ciphers he wasn't murdering innocent civilians. There also remained an outside chance that Zodiac would rise to the challenge and create a code, "however complicated", that Dr Marsh and his fellow cryptographers could unpick. This article, rather than a straightforward challenge to Zodiac, could have been deliberately manufactured with the assistance of detectives, to bait the Zodiac Killer into using a particular methodology in his cipher construction. If the police knew the source of Zodiac's inspiration, then it could unearth the cipher technique he employed when designing his next code. 

'Nobody' considered the idea that the Zodiac Killer may have used a foreign language in the cipher, or possibly a rotating key that switches at certain intervals. By employing such a technique, the Zodiac Killer could make the cipher virtually "crackproof". 
The article in the October 22nd 1969 San Francisco Examiner may have been specifically designed to lead the Zodiac Killer down a particular path, making his next cipher easier to crack. Dropping innocuous sections of text into an article such as "to quote Edgar Allen Poe, that any cipher created by man can be solved by man", can be specifically designed to guide the Bay Area murderer into using one of Edgar Allan Poe's cipher techniques or a model suggested by him. We know the Zodiac Killer was an avid reader of the newspapers and may have took this bait of using a publication by Edgar Allan Poe, thinking he was getting one over on Dr Marsh and the police. The hope from the standpoint of law enforcement, was that the Zodiac Killer would bite the hook and get reeled in. 

Sixteen days later the Zodiac Killer mailed the 340 cipher revealing, not his name, but his identity, carefully positioned at the base of his cipher. This catapulted the idea that the Zodiac Killer had indeed responded to the article by Dr Marsh, but wasn't quite ready to reveal his name to authorities. But it is my belief that the Zodiac Killer did create the 340 and 13 Symbol ciphers in tandem, with a view to inextricably link his identity to his name using the word "Zodiac" on the final row of the 340 cipher, with the three 8's as the conduit between the two. See here.

The Zodiac Killer, however, would hold back his '13 Symbol' cipher for approximately six months. Zodiac researcher Michael Cole stated "Clearly, the Zodiac did not send the cryptogram to Marsh, as had been requested (this non-public way of satisfying the challenge was apparently unacceptable to the attention-craving serial killer). Neither did he respond in a time frame that most would have expected. But these details matter little. In fact, the timing itself provides yet another reason to conclude that what we have here is a specific instance of cause and effect. As mentioned, this article was published in the Examiner on October 22, 1969.  Six months to the day later, April 22, 1970, the people of the San Francisco Bay Area were reading about the My Name Is cipher in the Chronicle."

But there may have been a much more cunning reason why the Zodiac Killer delayed his mailing of the April 20th 1970 communication, and it has everything to do with Edgar Allan Poe. Did the Zodiac Killer pick up on the wording of Dr. D.C.B. Marsh in the article, create and mail his '13 Symbol' cipher based on something in the writings of Edgar Allen Poe? 

We can see in the Edgar Allan Poe essay 'A Few Words on Secret Writing,' at the very beginning he shows the alphabet being split into two halves of 13 letters, A to M, and N to Z.
"Were two individuals, totally unpractised in cryptography, desirous of holding by letter a correspondence which should be unintelligible to all but themselves, it is most probable that they would at once think of a peculiar alphabet, to which each should have a key. At first it would, perhaps, be arranged that a should stand for z, b for y, c for x, d for w, &c. &c.; that is to say, the order of the letters would be reversed. Upon second thoughts, this arrangement appearing too obvious, a more complex mode would be adopted. The first thirteen letters might be written beneath the last thirteen, thus:
n o p q r s t u v w x y z
a b c d e f g h i j k I m; and, so placed, a might stand for n and n for a, o for b and b for a, &c. &c. This, again, having an air of regularity which might be fathomed, the key alphabet might be constructed absolutely at random." ​​

The Zodiac Killer not only created the April 20th 1970 cipher with 13 characters, but it too began with an A and ended with an M, just like the suggested encryption technique featured by Edgar Allan Poe. Notice the way the cipher is organized symmetrically using the alphabetical characters, the three 8's and the two symbols. The same symmetry was observed when placing half the alphabet alongside the 13 character cipher. See here.  

The Dr. Marsh newspaper article opened with "A Challenge perhaps unique in the annals of American crime was injected today into the bizarre case of the killer who begins his letters to newspapers 'This is the Zodiac Speaking'."
The article continued, and bemoaned the fact that Zodiac hadn't revealed his true identity: "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." 

'A Few Words on Secret Writing' stated "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." ​link. 

If the Zodiac Killer was basing the '13 Symbol' cipher on the Dr. Marsh article and secret writing of Edgar Allan Poe, why did he wait approximately six months to mail it to the San Francisco Chronicle?
It may not have been the six month anniversary that was important to him, but the only date mentioned in the Edgar Allan Poe literature, 'A Few Words on Secret Writing'. The date was April 21st. 
Had the Zodiac Killer deliberately waited six months to ensure his '13 Symbol' cipher letter would be postmarked April 21st, or be published on April 21st, which unfortunately for him never materialized? He was slightly early on the mailing, resulting in the postmark of April 20th, and the San Francisco Chronicle published his cipher in the April 22nd edition, effectively thwarting any intentions to recreate the Connecticut letter.

However, the possibility remains, that the Zodiac Killer could have used one of the cipher techniques employed or suggested by Edgar Allan Poe in 'A Few Words on Secret Writing', and the idea proposed by 'Nobody' regarding the use of a second language as the key, a much more viable proposition than initially considered.
​
 "It is not to be supposed that Cryptography, as a serious thing, as the means of imparting important information, has gone out of use at the present day. It is still commonly practised in diplomacy; and there are individuals, even now, holding office in the eye of various foreign governments, whose real business is that of deciphering. We have already said that a peculiar mental action is called into play in the solution of cryptographical problems, at least in those of the higher order. Good cryptographists are rare indeed; and thus their services, although seldom required, are necessarily well requited. An instance of the modern employment cipher is mentioned in a work lately published by Messieurs Lea & Blanchard, of this city–“Sketches of Conspicuous Living Characters of France.” In a notice of Berryer, it is said that a letter being addressed by the Duchess de Berri to the legitimists of Paris, to inform them of her arrival, it was accompanied by a long note in cipher, the key of which she had forgotten to give. “The penetrating mind of Berrver,” says the biographer, “soon discovered it. It was this phrase substituted for the twenty-four letters of the alphabet–Le,gouvernement provisoire.” 'A Few Words on Secret Writing' by Edgar Allan Poe.

In the last three articles it was proposed that the author of the 408 cipher may have left his identity within the final 18 characters. He specifically told us that he would not give us his name, but assured us his identity was concealed within the cipher - reasoned to be something like "I am the Zodiac Killer." The theme of his identity and name were integral to the final third of the cipher and letter mailed to the San Francisco Chronicle on July 31st 1969, and may very well have manifested through both his second and third ciphers as well. The third cipher began with "This is the Zodiac speaking. By the way have you cracked the last cipher I sent you. My name is...."- therefore, the final line of the second cipher (340 cipher) may be the 'narrative bridge' between the first and third cryptic offerings. 

The first cipher achieved everything the Zodiac Killer had wished for. He had fashioned using threats and newspaper rivalry maximum exposure for his handiwork, which was very quickly published by the Vallejo Times-Herald, San Francisco Examiner and San Francisco Chronicle. The failure of Zodiac to give us his name did not satiate the desire of some in the quest for the real identity of the killer, and was championed by Dr D.C.B. Marsh, president of the American Cryptogram Association, who on October 22nd 1969 in an article published by the San Francisco Examiner, stated "The killer wouldn't dare, as he claimed in letters to the newspapers, to reveal his name in a cipher to established cryptogram experts. "Zodiac" had not done this, Marsh suggested, 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."

​This article was not to go unnoticed by the killer, who, two and a half weeks later mailed his infamous 340 cipher, unsolved to this day according to official sources. This cipher was to become the all-important bridge between cipher one and three. If he gave us his identity (the Zodiac Killer) in the unsolved 18 characters of cipher one, and stated "my name is" in cipher three (supposedly giving us his name), then by logical extension, cipher two should have been the promise of a name, and the conduit between the two.

If we can provide a compelling reason to show that the near-Zodiac on the final line of the 340 cipher was actually intended to be deciphered to 'Zodiac', then we are left with the final two characters of the cipher to decode, thereby bridging the gap between cipher two and three. 
Using the most powerful supercomputers in the world and the talent of some of the brightest minds in cryptography, the 340 cipher has failed to buckle. So, it's time to use the character of the Zodiac against himself, and his willingness to respond to the newspapers.

If the Zodiac Killer is responding to Dr D.C.B. Marsh, then he clearly isn't prepared to give us his name immediately in the November 8th 1969 '340 cipher', as the opening line in his April 20th 1970 communication would testify to. It would be over five months later that he stated "my name is".  Therefore, the final two characters of the 340 cipher are the conclusion to an open-ended promise of something more to come, in similar fashion to "my name is."  The Zodiac Killer certainly wasn't going to miss the opportunity to keep Dr D.C.B. Marsh and the public waiting just a little bit longer. 
​
The final line or sequence of the 340 cipher probably read "The next cipher will reveal who the Zodiac is" or "I will soon reveal who the Zodiac is" - or something along these lines. This 'promise' can be seen in his opening gambit of the April 20th 1970 communication: "This is the Zodiac speaking. By the way have you cracked the last cipher I sent you. My name is...." ​
The statement of "by the way have you cracked the last cipher I sent you" is superfluous, as he knows only too well the 340 cipher has not been cracked, yet, it also lacks his usual abrasive sarcasm. However, it is followed by "my name is", and therefore could be construed as the conclusion to his promise from the final line of his 340 cipher and to Dr D.C.B. Marsh, and the allegorical  bridge between the two ciphers.

But how do we know that the near-Zodiac on the final line of the 340 cipher was to be decoded to 'Zodiac'?  Because he fashioned a bridge between cipher two and three using his pseudonym. Placing the real spelling of Zodiac under the '340 cipher' version of Zodiac, and counting the alphabetical difference numerically between the columns (see here), we achieve the numbers 000888. When combined, the three circled 8's found on the '13 Symbol' cipher.
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These six characters of the 340 cipher were effectively carried forward numerically and placed front and center of the '13 Symbol' cipher design. You will also notice that the two characters either side of three 8's (shown on the right), are both visible either side of the near-Zodiac on the 340 cipher. A total of eight characters and three circled 8's the common link or bridge between cipher two and three - in which the name of Zodiac played a pivotal part in the formation of the 'My Name is Cipher'. The story is now complete. 

The Zodiac Killer stated on July 31st 1969 "I will not give you my name, but in this cipher is my identity." He promised in the 340 cipher, in a response to Dr D.C.B. Marsh, that he would soon reveal his name. Then, five and a half months later, on April 20th 1970 he stated "This is the Zodiac speaking. By the way have you cracked the last cipher I sent you. My name is...." 

Do ciphers two and three really contain a full and coherent message, not dissimilar to the 408 cipher solution, or had the Zodiac Killer taken Dr D.C.B. Marsh's advice "to send The American Cryptogram Association a cipher code - however complicated", and taken it a step too far?

This is the final installment covering the 18 unsolved characters at the foot of the 408 cipher. Part one. Part two.
Nobody knows for sure the exact process in which the Zodiac Killer crafted the three ciphers mailed to the San Francisco Chronicle, San Francisco Examiner and Vallejo Times-Herald, but one possibility is that the author wrote the message first and then transferred it to the chosen grid formation, with the intention of leaving a number of spaces to insert his identity at the end of the cipher - a signature of sorts. The killer actually stated this: "I want you to print this cipher on the front page of your paper. In this cipher is my idenity."

We now know his identity as the 'Zodiac Killer', so one may expect to see 12 unsolved characters remaining at the foot of the cipher. He could have signed off the cipher with the wording 'Zodiac Killer' or 'I am the Zodiac', but either way, he would have had to leave himself 12 available spaces to complete the entire grid of 24 rows and 17 columns. The reason for believing he intended to leave 12 characters for his identity, rather than 18, is that he transferred the message from draft to grid incorrectly, actually omitting one important word - people.
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The author had just switched from cipher 2 to cipher 3 (see below), which may have instigated the error.
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In the trinity of letters to the newspapers, the Zodiac Killer described the inevitable consequences of not printing his ciphers. 
To the Vallejo Times-Herald, he wrote "I will cruse around and pick of all stray people or coupples that are alone then move on to kill some more untill I have killed over a dozen people."
To the San Francisco Examiner, he wrote "If you do not print this cipher, I will go on a kill rampage Fry night. This will last the whole weekend, I will cruse around killing people who are alone at night untill Sun Night or untill I kill a dozen people." 
To the San Francisco Chronicle, he wrote "I will cruse around all weekend killing lone people in the night then move on to kill again, until I end up with a dozen people over the weekend."  

With regards to his threats, he used the word "people" no less than six times, so it was probably unfortunate that this was the word he mistakenly dropped from his grid when transferring the message to it.
The murderer wrote in the cipher "the best part of it, is that when I die I will be reborn in paradice and all the I have killed will become my slaves." It is highly likely that he accidentally reproduced his message incorrectly and failed to include the word "people" in the resultant cipher. The cipher should have read "the best part of it, is that when I die I will be reborn in paradice and all the people I have killed will become my slaves."

Since "killing", "kill" and "people" were routinely written 'hand in glove' in all the three newspaper communications, then it is no great leap of faith that the two words should have been bound together in the cipher as well. 
In the San Francisco Chronicle portion of the cipher below, I have added "people" into the grid, thereby shifting the cipher across six spaces. The resulting cipher now contains 396 characters of legible text, leaving only 12 unsolved characters at its foot. The 12 characters we discussed earlier, in which the author had reserved for his identity or pseudonym. Signing off with the 'Zodiac Killer' or 'I am the Zodiac'.

However, the Zodiac Killer had made an error, accidentally omitting the word "people", and consequently had to improvise by using a combination of 'Zodiac Killer' and 'I am the Zodiac' to enable full use of all 408 spaces on the 24 X 17 grid. He may have settled for 'I am the Zodiac Killer', thereby satisfying the 18 spaces he had inadvertently left himself.

The idea of a 396 letter message (including "people" within it) would have negated the possibility of creating 30 rows by 13 columns totaling 390 characters - which is why he didn't do it. Therefore, he opted for 17 by 24, creating the grid we have been accustomed to. 

What methodology he employed to encrypt these final 18 letters is another matter entirely.    

The blue square shows the end of the word "the". One can see that by moving the letter 'E' across two places to accommodate "those", the remainder of the cipher would be equally shifted. If we added "people" after "the", then the remainder of the cipher would be shifted six places across. The result of this would be removing the final 2 or 6 characters from the 408 cipher.

This strikes to the heart of whether the Zodiac Killer originally intended to leave a predetermined identity at the foot of the cipher. He ended up with 18 characters, which to this day remain unsolved. If he had intended to place "those" or "people" in the cipher, but transferred his message incorrectly, then the idea that 18 characters were purposely left to reveal his identity fails to materialize. His new identity would drop to 12 or 16 characters. The 4 consecutive character drop down, from the 8th to 24th line, would also not occur. 

In the last article I suggested that the final 18 characters could read "I am the Zodiac Killer", based on his wording in the trinity of July 31st 1969 communications. With the addition of "people" his intended message could have been relegated to the signature "Zodiac Killer" or "I am the Zodiac" ​ With the addition of "those", an altogether different message would likely have been created. His original intention may have been to create a 12 or 16 character message, but was forced to improvise into a longer version, created by the error on line 17. However, this would negate the premise of the previous article to some extent.
 
To presuppose an original 18 characters being left over for the designated purpose of his identity, would make the assumption that his original message read "The best part of it is that when I die I will be reborn in paradice and all the I have killed will become my slaves," and he transferred it to the cipher correctly.

The idea of a random filler to flesh out a cipher doesn't sit well, when we consider how easy it is to just slightly redesign the message to use all the 408 available spaces. This suggests the 18 unsolved characters do have meaning, and do contain the identity or pseudonym of the Zodiac Killer. This makes more sense than a real name, bearing in mind the author has already decided against this option on lines 18 and 19.

If the Zodiac Killer's original message was 392 or 396 letters in length, he could have created a completely different grid formation with reduced leftovers or none at all, such as 6 rows of 22 characters = 132, mailed to each of three newspapers. This would give us a total of 396. However, he chose to opt for 17 characters in each row, thereby leaving more unused characters. For this reason, there appears a purpose behind the notion of a killer leaving us his identity.
​
Since he hadn't revealed his pseudonym at this juncture, can we assume that part of the 18 unsolved characters held the words "Zodiac Killer." The precursor of "I am the"- the beginning of the 18 characters, just like the introduction written on the San Francisco Examiner and Vallejo Times-Herald newspapers.   

THE 18 UNSOLVED CHARACTERS [PT1]  
THE 18 UNSOLVED CHARACTERS [PT3]

In a previous article it was considered that the Zodiac Killer's identity was born on August 3rd 1969, but on this occasion I shall take an altogether different approach, and consider the possibility that the Bay Area murderer had already decided upon the pseudonym Zodiac when he mailed the trinity of letters and ciphers to the Vallejo Times-Herald, San Francisco Examiner and San Francisco Chronicle on July 31st 1969.
The San Francisco Chronicle letter (part 3) reads as follows "Here is part of a cipher the other 2 parts of this cipher are being mailed to the editors of the Vallejo Times and SF Examiner. I want you to print this cipher on the front page of your paper. In this cipher is my idenity. If you do not print this cipher by the afternoon of Fry.1st of Aug 69, I will go on a kill ram-Page Fry. night. I will cruse around all weekend killing lone people in the night then move on to kill again, until I end up with a dozen people over the weekend." The final 18 characters of the San Francisco Chronicle code remain undeciphered. However, the clues to breaking the remaining portion of the cipher may reside within the letters themselves. 
The 408 cipher message read "I like killing people because it is so much fun it is more fun than killing wild game in the forrest because man is the most dangerous animal of all to kill something gives me the most thrilling experence it is even better than getting your rocks off with a girl the best part of it is that when I die I will be reborn in paradice and all the (people) I have killed will become my slaves I will not give you my name because you will try to slow down or stop my collecting of slaves for my afterlife. ebeorietemethhpiti."  The unbroken characters are shown in red.     

The murderer chose his words carefully, stating "in this cipher is my identity" rather than his name. This became evident when the vast majority of the 408 cipher was cracked a matter of days later, and the killer revealed "I will not give you my name because you will try to slow down or stop my collecting of slaves for my afterlife." This still left open the possibility that his identity or pseudonym was contained in the 408 cipher. The San Francisco Chronicle letter was the only one of the trinity that contained "in this cipher is my identity," so logically, one could conclude that the 18 undeciphered characters at its foot, was the location of the murderer's identity.
If the killer had already decided upon his pseudonym when he wrote the three July 31st 1969 letters, then his decision to begin all three letters with "This is the murderer" and "I am the killer" (twice) was deliberately engineered to withhold the pseudonym Zodiac from the letters. The reason being - it was concealed in the final 18 characters of the 408 cipher.
It could be argued, that if he was to reveal his identity or pseudonym in the 408 cipher, then logically he would sign off the cryptogram with it. This was also apparent in the 340 cipher, with the near-Zodiac tantalizingly placed on the final line. 
If the Zodiac Killer had revealed his pseudonym straight away, then one of the letters would have opened with "This is the Zodiac" rather than "This is the murderer" (exactly like the August 4th 1969 letter). The other two letters would have opened with "I am the Zodiac Killer" rather than "I am the killer". But the murderer and author of the letters wanted to hide his pseudonym for now, and conceal it in the final 18 characters of the 408 cipher.    

We can now complete the 408 message:
"I like killing people because it is so much fun it is more fun than killing wild game in the forrest because man is the most dangerous animal of all to kill something gives me the most thrilling experence it is even better than getting your rocks off with a girl the best part of it is that when I die I will be reborn in paradice and all the (people) I have killed will become my slaves. I will not give you my name because you will try to slow down or stop my collecting of slaves for my afterlife. I am the Zodiac Killer."​
This is an attempt at reasoning a solution from within the letters themselves, and not a claim of a definitive solution 

THE 18 UNSOLVED CHARACTERS [PT2]
THE 18 UNSOLVED CHARACTERS [PT3]