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.        

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". 
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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.
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 "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]

There is no definitive evidence to totally negate the idea that the 340 cipher contains a viable solution- with the mystery and allure of the Zodiac Killer code the driving force behind people wishing it were genuine. This, of course, exempts the 500+ people who have already solved the 340 cipher, in solutions now extending longer than the Bayeux Tapestry.  
Obviously, Zodiac researchers who specialize in the ciphers rather than the crimes themselves, have a vested interest in wishing the cipher to be a hidden message. This is the belief that keeps the dream alive.
But did the Zodiac Killer really have the ability to create a more difficult cipher than the 408, with a reasonable expectation of a solution. Placing 29 unique characters into a 32 symbol cipher, and creating a 13 symbol code would suggest not.
The October 22nd 1969 Examiner newspaper article by Will Stevens, laid down a challenge to the Zodiac Killer from the president of the American Cryptogram Association (ACA), Professor D.C.B. Marsh, to reveal his name. This may be the article that inspired the 340 cipher, and by association, the 'Halloween' card mailed approximately one year later.
 "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, which will truly and honestly include his name."
This contention is probably true- that the Zodiac Killer wouldn't reveal his name in any cipher (other than his pseudonym), and additionally, he likely used the fact "that any cipher created by man can be solved by man" as a springboard to create something extra special, other than a cipher. If we contend that the Zodiac Killer wrote his final letters in 1974, then is it likely that a killer touted as an attention seeker, could resist dropping us clues to the 340 cipher in his subsequent letters, spanning in excess of four years. 
Each and every one of his final three communications in late 1970 and early 1971 effectively told us he was crackproof. The upside down text on the October 5th 1970 'Pace' card stated "Fk I'm crackproof." The October 27th 1970 'Halloween' card proclaimed "sorry no cipher." The March 13th 1971 'Los Angeles' letter boasted "Like I have allways said, I am crack proof." But the Zodiac Killer hadn't always said he was crackproof- only in the two communications either side of the 'Halloween' card announcing "sorry no cipher." The suggestion he was crackproof, thereby not arising from his perceived ability to evade police, but from his smugness in knowing he created three ciphers he knew would never be solved. 

The Tim Holt comic find by Tahoe27 in 2013, and the recent assertion of a close alliance, not only with the 'Halloween' card, but the 340 cipher, has been covered here to reject the 340 cipher as containing a viable and coherent message.
In view of the "by knife" attribution on Bryan Hartnell's car door, it is arguable that the Zodiac Killer had the Tim Holt comic book or Rota Fortunae (Wheel of Death) in mind as he wrote on the car door. In other words, the concept predated the September 27th 1969 Lake Berryessa stabbings, rather than just the 'Halloween' card. The Lake Berryessa "by knife" attribution becoming the part inspiration for the complex puzzle of the 340 cipher.
The "by knife" method of death (on the right) is clearly the only one falling within its quadrant, as opposed to the others, which are all connecting with the central column.
This method of death was certainly prioritized by the Zodiac Killer, having placed it on Bryan Hartnell's vehicle (despite the fact the crime was obviously committed with a knife). The feasible presence of "by knife" within the 340 cipher. The possibility of a crude 'Halloween' card design in the December 16th 1969 'Fairfield' letter featuring "death by knife," along with the "Bleeding Knife of Zodiac" drawing. And finally, the 'October 27th 1970 'Halloween' card design and comic book, both containing "by knife" and mirroring the 340 cipher and 'Fairfield' letter.
Below are the speculative beginnings, attempting to interweave the '13 Hole' postcard into the emerging design. 

This is the last time this subject will be tackled for the foreseeable future, unless something magical sticks its head above the parapet- but before that happens- there is just one more addition to the idea of an extremely close alliance between the 'Halloween' card and 340 cipher, and the suggestion that the 340 cipher is not a meaningful and coherent message by the Zodiac Killer.
Just about every feature of the October 27th 1970 'Halloween' card, including the envelope and stamp, can be shown to exist within the 340 cipher, making the December 2013 discovery by Tahoe27, of a Tim Holt comic book connection, all the more compelling. Her discovery may have opened the door to finally end the debate on the validity of the 340 masterpiece, and place the pseudonym 'Zodiac' front and center to the 'Death Wheel' featured on the comic book cover.
At what juncture the Zodiac first stumbled across his pseudonym is of little importance, however, it could be argued that when he found it, he would likely research the name 'Zodiac' and use elements of his research to incorporate into his future correspondence. If he had happened upon the Tim Holt 'Death Wheel' comic prior to November 8th 1969, then the light bulb may have switched on, and his design of a crackproof cipher began in earnest. And possibly, a 340 cipher designed in tandem with the Tim Holt comic and cipher three, which he mailed just over five months later on April 20th 1970. His opening line of "This is the Zodiac speaking. By the way have you cracked the last cipher I sent you. My name is....", he may have already known the answer to when he manufactured the illusion of a 340 character message.        

Here is a brief recap before we move on.
The 'Halloween' card stamp contained 17 letters "In the beginning God" that slotted nicely onto the first line of the 340 cipher, with characters 15,16 and 17 awkwardly similar- including the half-earth image present on the stamp.
Paradice and Slaves can be shown as a distinct possibility, bisecting the 340 cipher horizontally and vertically, just like the 'Halloween' card arrangement. Seventeen characters horizontally and vertically in either direction, to create the perfect crosshairs of Zodiac.
The word "by" can be found in all four quadrants of the 340 cipher, mirroring the 'Halloween' card arrangement.
At least seven, possibly eight characters on the 14th line of the 340 cipher can be formed into the design of the 'Halloween' card inner. Explanation here. 
"Sorry no cipher" written on the envelope inner and designed in similar fashion to Paradice and Slaves arrangement on both the 'Halloween' card and 340 cipher, explicitly instructed us that no cipher existed on November 8th 1969.
One has to presume that all these fell here by accident (including the inference to Zodiac on the 20th line), because to believe otherwise, would pour huge doubt on a Zodiac Killer who was able to simultaneously create a uniform message within the 340 cipher in conjunction with a 'bag of puzzles'. 
However, the Tim Holt 'Death Wheel' comic is not only interesting because it contains By Fire, By Gun, By Rope and By Knife, found in the 'Halloween' card, or because of "Redmask" or "Lady Doom," but because of the origin of the 'Death Wheel' or 'Wheel of Fortune' itself. 
Had the Zodiac Killer read anything about the pseudonym 'Zodiac' when he first appropriated it, then he may have known the relevance of the 'Wheel of Fortune' or 'Rota Fortunae,'. thereby triggering the inspiration for the 340 cipher, and the eventual 'Halloween' card explanation or solution to his devilish trick and treat.          

We could just assume that when the Zodiac Killer spotted the Tim Holt 'Death Wheel' comic book, he liked the fact it represented some or all of his killing methods, and simply chose it because of its menacing touch. However, he may have chosen it because of the pseudonym he had grown so attached to- a pseudonym he would seemingly place at the foot of the 340 cipher.
The 'Wheel of Fortune' or 'Rota Fortunae' has a long and rich history, crossing many cultures and eras. Here is an excerpt from Wikipedia:
"In medieval and ancient philosophy the Wheel of Fortune, or Rota Fortunae, is a symbol of the capricious nature of Fate. The wheel belongs to the goddess Fortuna (Greek equivalent Tyche) who spins it at random, changing the positions of those on the wheel: some suffer great misfortune, others gain windfalls. Fortune appears on all paintings as a woman, sometimes blindfolded, "puppeteering" a wheel."
The great windfall may be the promise of paradise, but the downside is the servile nature expected by the one who summoned you.
But here is the interesting part- again taken from Wikipedia. 
"The origin of the word is from the "wheel of fortune" - the zodiac, referring to the Celestial spheres of which the 8th holds the stars, and the 9th is where the signs of the zodiac are placed. The concept was first invented in Babylon and later developed by the ancient Greeks. The concept somewhat resembles the Bhavacakra, or Wheel of Becoming, depicted throughout Ancient Indian art and literature, except that the earliest conceptions in the Roman and Greek world involve not a two-dimensional wheel but a three-dimensional sphere, a metaphor for the world. It was widely used in the Ptolemaic perception of the universe as the zodiac being a wheel with its "signs" constantly turning throughout the year and having effect on the world's fate (or fortune)." link.
The zodiac is an area of the sky that extends approximately 8° north or south (as measured in celestial latitude) of the ecliptic, the apparent path of the Sun across the celestial sphere over the course of the year. The paths of the Moon and visible planets are also within the belt of the zodiac. The Zodiac is divided into 12 signs beginning with Aries and Taurus.
The Zodiac wheels have multiple cultural adaptations, shown here in a Wordpress blog:
"These zodiac/time wheels are not common in Eastern Orthodox iconography, but they are found in one variation or another occasionally — usually, as here — in the form of wall paintings in churches. When seeing such a “Wheel of Time” — also called a Wheel of Life — one cannot help thinking of those Tibetan images that also represent a wheel of life as the “Wheel of Becoming” — in this case a wheel of rebirth:"
Here is one final extract from the book 'Deep Value:
Plutarch says that Servius knew "fortune is of great moment, or rather, she is everything in human affairs" because it was through good fortune that he had ascended from slave to king. In Roman mythology Fortuna was the goddess of fate, and the personification of chance. She turned the Rota Fortunae- the Wheel of Fortune- which dictated the destiny of man." Therefore, did Zodiac dictate the destiny of his victims-  By Fire, By Gun, By Rope and By Knife- the very reason the 'Wheel of Death' portrayed on the Tim Holt comic was so very appealing.

The discovery by Tahoe27 linking the Tim Holt comic was fascinating in so many ways, yet, it may not have been the inspiration behind the 'Halloween' card, but the inspiration behind the 340 cipher and its accompaniment- the '13 Symbol' cipher.
If the Zodiac Killer had done his research and discovered the 'Wheel of Fortune' or 'Rota Fortunae', and its connection to the word 'Zodiac', then the Tim Holt comic may have been a gift from heaven- an offering he just couldn't resist. 
Five weeks after the November 8th 1969 340 cipher, the December 16th 1969 'Fairfield' letter may have shown the early machinations of the Zodiac design, appearing in rudimentary code- the full explanation of which would have to wait until October 27th 1970..
The interconnectivity between the 'Halloween' card, Tim Holt 'Death Wheel' comic, the pseudonym 'Zodiac' and the 340 cipher is an intriguing and perplexing blend of mystery. One that came together by deliberate intent, or came together from the mind of somebody wishing it were true.

This is a continuation of the article 'The Illusion of the 340 Cipher,' attempting to show Zodiac's second code was nothing more than a collection of puzzles, interconnected to his other mailed correspondences.   
The 'Halloween' card mailed by Zodiac on October 27th 1970 predominantly featured within the 340 cipher, in that, Paradice and Slaves was able to be shown bisecting the cipher horizontally and vertically across its mid-section, along with 'by' being found in all four quadrants. The text of the stamp 'In the Beginning God' fitted nicely on the first line of the cipher, with the word 'God' aligning nicely with characters 15, 16 and 17. In addition, the half-earth image on the stamp mirrored exactly with character 16.
The idea that all these connections to the 'Halloween' card, '13 Symbol' cipher and 'Exorcist' letter could be forged within the 340 cipher by chance, was presented as so unlikely, they must have been created by design.
The darkened section of the 'Halloween' card inner reads like an instruction manual. The skeleton's finger of 4-TEEN directing us downwards 14 lines, to find the word 'BOO.'
The 14th line containing four shaded circles, three of which can be formed into the word BOO, complete with exclamation mark (I + black circle).
The next feature on the 'Halloween' card is the strange symbol.  
​  

The following two characters on the 14th line of the 340 cipher can easily be rearranged, by reversing the letter F and attaching its adjacent character, to mimic the strange symbol on the 'Halloween' card. 
​The next feature on both the 14th line and 'Halloween' card is the letter N and the letter Z. Rotating the N ninety degrees clockwise forms the completed sequence of BOO!, strange symbol and letter Z on the 340 cipher.
This is achieved using 8 characters on the 340 cipher, all in close proximity to each other. Just like 'In the Beginning God' and 'Paradice and Slaves,' is this another stroke of luck, or has this been deliberately fashioned by the Zodiac Killer as part of a game. 
It is further apparent that the word 'BOO' (in reverse) bisects the word 'Paradice' running vertically down the cipher, separating the letters I and C.
On the 'Halloween' card in this approximate area, the Zodiac Killer has mirrored the letter N, which may or may not hold some significance.
This could be a case of simply looking for patterns and finding them, but with so many having now been unearthed, is this compounding evidence to reliably dismiss the 340 cipher as harboring a coherent and uniform message, as demonstrated by the 408?
The Zodiac Killer may have dropped several clues in his later communications, resisting the temptation of giving us the final solution:
"But, then why spoil the game."    

It would be befitting that the Zodiac Killer's last correspondence may possibly be the 'Eureka' card mailed in the December of 1990, considering the last major work of Edgar Allan Poe was the non-fiction offering Eureka: A Prose Poem.    
"Adapted from a lecture he had presented, Eureka describes Poe's intuitive conception of the nature of the universe with no antecedent scientific work done to reach his conclusions. He also discusses man's relationship with God, whom he compares to an author. Similar to his theories on a good short story, Poe believes the universe is a self-contained, closed system. In coming to his conclusions, Poe uses ratiocination as a literary device, through his character C. Auguste Dupin, as if Poe himself were a detective solving the mystery of the universe. Eureka, then, is the culmination of Poe's interest in capturing truth through language, an extension of his interest in cryptography. Some modern critics believe Eureka is the key to deciphering meaning in all Poe's fiction, that all his works involve similar theories." Wikipedia. Strange therefore, that the Christmas card possibly engineered by Zodiac should contain a cryptic message in the form of photocopied keys mailed from Eureka, California.
This is not the only time that Edgar Allan Poe may have played a part in a cryptic message mailed by the Zodiac Killer. It could have been the essay 'A Few Words on Secret Writing' that inspired the creation of the '13 Symbol' cipher mailed on April 20th 1970 by the Bay Area murderer. A cipher that was devised sometime between October 22nd 1969 and November 8th 1969, and belatedly mailed by the killer some 6 months later, with the accompanying text about the murder of San Francisco police officer Brian McDonnell on February 16th 1970. Secret Writing from our Secret Pal.      

Michael Cole wrote an excellent article entitled "My Name Is" Cipher Motivation that suggested the Zodiac Killer likely drew his inspiration for the '13 Symbol' cipher from an October 22nd 1969 newspaper article by Will Stevens, which laid down a challenge to the Zodiac Killer from the president of the American Cryptogram Association (ACA), Professor D.C.B. Marsh, to reveal his name. Apparently, several months later the killer duly obliged by opening his correspondence with the line "This is the Zodiac speaking. By the way have you cracked the last cipher I sent you. My name is...." 
He followed this by placing 13 characters underneath, widely believed to be the Zodiac Killer offering us his name. 
One couldn't help considering whether this cipher was not only created because of the newspaper article, but whether this cipher was created based on what was contained within the article- in particular the works of Edgar Allan Poe. This would be right up Zodiac's alley, devising a cipher based in the text of the newspaper article. 
Here is an excerpt "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, which will truly and honestly include his name."

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:
"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." 

Quite fortunate that the Zodiac Killer, after possibly reading this newspaper article, should then create a cipher of 13 characters beginning with an A (the first letter of the alphabet) and ending with an M (the 13th letter of the alphabet), just like Edgar Allan Poe's construction in his essay 'A few Words on Secret Writing.'  
Throughout the newspaper article Professor D.C.B. Marsh is urging the Zodiac Killer to give his name, which clearly he wasn't going to achieve with such a limited number of characters, but he may have played a game with D.C.B. Marsh by offering us another cryptic message within the cipher. We contended previously that the 340 cipher and '13 Symbol' cipher were both likely created at the same time because of the interconnectivity between the two. The name Zodiac appeared to be numerically carried forward from the 20th line of the 340 to the '13 Symbol' cipher in the form of three circled 8's. This was achieved by placing the correct spelling of Zodiac alongside the 'near Zodiac' and numerically counting the difference between the columns. This produced perfect numerical symmetry, as did placing A to M (half the alphabet) alongside the '13 Symbol' cipher. For this to be achieved, it was argued the two ciphers must have been created with each in mind, and therefore both devised before November 8th 1969. See image here for explanation or read article 'Heaven Sent'.  
"In Christian numerology, the number 888 represents Jesus, or sometimes more specifically Christ the Redeemer. This representation may be justified either through gematria, by counting the letter values of the Greek transliteration of Jesus' name, or as an opposing value to 666, the number of the beast. "  
Wikipedia.
Curiously, if you visit the English gematria site here and enter Edgar Allan Poe into the calculator, 666 is achieved.    
​Was the Zodiac Killer playing games, giving us the name Jesus in the form of a numerical value and depicting himself as the savior of souls for the afterlife.

Professor D.C.B. Marsh attempted to coerce the Zodiac into giving us his name by stroking his ego- so it seemed rather unusual that every alphabetical letter within the '13 Symbol' cipher apart from one, could be found in the word 'NAME'. The Zodiac Killer gave us A twice, M twice, N twice and E once. The only exception was the letter K- the only letter the Zodiac Killer scrubbed out in the 340 cipher. Removing this from the '13 Symbol' cipher only leaves us with letters contained in the word NAME.
The creation of these two ciphers together is the only reasonable explanation for a correlation between the two (if one exists), and the inspiration of Edgar Allan Poe in the construction of the '13 Symbol' cipher, based upon splitting the alphabet down its center, was ultimately born from the article by Will Stevens.
​Edgar Allen Poe stated that "any cipher created by man can be solved by man."
Could it be that, any cipher created by Zodiac can be solved by Edgar Allan Poe.

This is a combination of previous articles (with a little extra) under one banner, attempting to dispel the idea that the 340 code is a genuine cipher, and all attempts at trying to reveal a continuous and coherent message will ultimately fail. 
By overwhelmingly consensus, the 340 cipher will soon be entering its 50th year unbroken, remaining impervious to all attempts at releasing its secrets, despite innumerable attempts by the best codebreakers and codebreaking machinery thrown at it. Either the Zodiac Killer created a cipher so stunningly impossible and misjudged the complexity of his cipher, or he didn't create one at all. The '13 Symbol' and '32 Symbol' codes were simply too short, with too many variables to be broken by conventional means. The '32 Symbol' cipher has 29 unique characters, meaning you can literally fill in the blanks however you choose. The '13 Symbol' cipher is simply too short to be called a cipher, and any solution proffered can be readily dismissed without a valid key. The Zodiac certainly wasn't stupid and must have known this- pouring huge doubt on whether he ever intended them to be solved in a conventional manner. Therefore, why should we treat the 340 cipher any differently. The whole thing just appeared to be one big game for the Zodiac Killer, as we huffed and puffed long into the night trying to pry open his ultimate masterpiece.
Many observers have wondered whether the Zodiac Killer mailed the 'code key' to the Vallejo Police Department on August 10th 1969 under the guise of a "concerned citizen," unaware that it had already been solved by Donald Gene and Bettye June Harden, as well as the FBI in Washington. Unusual that he should then sit on the 340 cipher for many years to come, able to resist the temptation of revealing his subsequent ramblings. Keeping a secret for nearly 50 years would certainly take great restraint from a killer who bathed in the spotlight.
The 340 cipher may very well have been designed in the mind of the killer as early as August 4th 1969, or the moment his 408 cipher was cracked. The decrypted 408 read: "I like killing people because it is so much fun it is more fun than killing wild game in the forest because man is the most dangerous animal of all to kill something gives me the most thrilling experience 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." 
The answer to the 340 cipher probably already lay within the text of the 408 cipher- just designed in an altogether different format. The clue would later reveal itself in the design of the 'Halloween' card, mailed on October 27th 1970, where the killer placed "Paradice" and "Slaves" in a cross formation, and told us "sorry no cipher." This wouldn't be the only time the Zodiac Killer gave us clues, alluding to the fact we were chasing a solution to a cipher that didn't exist.        

One of the best finds in recent years was by Tahoe27, a regular contributor to the Zodiac Killer Site forum, who discovered a connection between a Tim Holt comic and the 'Halloween' card. Many features on the cover of the comic parallel the 'Halloween' card, including the wording By Fire, By Gun, By Rope and By Knife, along with "Redmask" (the skeleton eyes) and "Lady Doom" (peek-a-boo you are doomed). However, I believe Tahoe27 is not convinced that the 'Halloween' card was authored by the Zodiac Killer. 
If the 'Halloween' card was authored by an impostor, who based the 'Halloween' card on the Tim Holt comic, then are we to believe he was extremely fortunate that a year earlier, the real Zodiac Killer just happened to create a 340 cipher containing the word "BY" in all four corners of the cipher, along with PARADICE and SLAVES being a possibility, running down and across the cipher on the midpoint vertically and horizontally, just like the configuration on the 'Halloween' card.
Admittedly, the words paradice and slaves have not been proven to exist in the 340 cipher, but the fact they are a distinct possibility by comparison to the 'Halloween' card appears another very fortunate stroke of luck- particularly if we believe the author of the 'Halloween' card wasn't the Zodiac Killer- and only considered the Tim Holt comic in his design of the 'Halloween' card. If the 'Halloween' card was crafted by the Zodiac Killer using only the Tim Holt comic, then the above still applies.
The more likely conclusion we could draw from this, is that the 340 cipher was designed with the Tim Holt comic in mind, and the 'Halloween' card (one year later) was giving us a clue.  

​On the right, we can see how the four words "BY" fit into each quadrant of the 340 cipher just like the 'Halloween' card offering. What are the odds that in each quadrant of 80 characters we would find the letters B and Y together either horizontally or vertically every time. Not to mention the fortunate appearance of paradice and slaves bisecting the cipher perfectly. The killer may even have given us his signature in the bottom right corner, along with the running total, which was seven and counting on November 8th 1969.
If this wasn't the intended design of the 340 cipher, then either the Zodiac Killer or an impostor got extremely lucky, in just happening upon a Tim Holt comic that mirrored the 340 cipher unintentionally. But we may just be able to prove a definite link between these two communications and confidently state that both were designed by the Zodiac Killer, and with a fair degree of confidence, argue that the 340 cipher is not a cipher in the true sense of the word. The majority of the characters likely filler, but in this instance, far more than the 18 characters at the foot of the 408 cipher. The reason we may be able to contend the 340 cipher is not a continuous and uniform message like the 408 cipher (and not a cipher as we believe one to be), is because the Zodiac Killer lined us up for a fall and then admitted to it a year later.
On the 'Dripping Pen' card accompanying the 340 cipher, the killer stated
"This is the Zodiac speaking. I though you would nead a good laugh before you hear the bad news. You won't get the news for a while yet. Could you print this new cipher in your frunt page? I get aufully lonely when I am ignored, so lonely I could do my Thing." Was that bad news to come on October 27th 1970, when he mailed the 'Halloween' card.
If we believe that the 'Halloween' card design is referring back to the 340 cipher, then the message concealed on the envelope inner of "sorry no cipher," is the Zodiac Killer finally admitting that the 340 cipher is not the real cipher we had thought.
He is declaring that the 340 is "no cipher," and is in fact, based upon the paradice and slaves configuration. This is why he crosses the phrase "sorry no cipher" to mimic the design of paradice and slaves, using 13 letters in both instances.
The Zodiac Killer could easily have written "sorry no cipher" just the once, but deliberately fashioned it to form a link between the 'Halloween' card design and the 340 cipher.
After searching for solutions to the 340 cipher for nearly half a century, the Zodiac Killer may have given us the answer to its design after just one year, but it was overlooked. We have took the phrase "sorry no cipher" as an apology, that he wasn't giving us a cipher in the 'Halloween' card, when in actual fact, he was apologizing for stringing us along for the best part of a year, and offered us the real solution to the 340 cipher on October 27th 1970, contained within the 'Halloween' card. You could say it was a "trick" and "treat" befitting of Halloween.

​You will notice that the paradice and slaves configuration from the 'Halloween' card fits nicely into the 340 cipher.
The two dashes on the 10th line are represented by the letter S. 
The left-facing V on the 9th column and 10th line are represented by the letter E. 
​The two addition signs on the 9th column are represented by the letter A.
When the letter R of paradice is placed into its only conceivable position, along with the L and V from slaves, it is reminiscent of the 'Halloween' card. What are the chances that this could be achieved accidentally?  

The word paradice travels vertically 17 lines, exactly matching the 17 columns that slaves travels horizontally.The Zodiac Killer placed crosshairs beneath the 9th column, the midsection of the cipher (shown here).
The intersection on the 'Halloween' card configuration forms RAD and LAV, exactly the same as the bisecting center point of the 340 cipher. The Zodiac Killer also underlined the LAV of Paul Averly on the Halloween card envelope, on which he also placed the intersecting "sorry no cipher" on the envelope inner. 
The 'Halloween' card stamp depicts the surface of the moon with a half-earth in the distance and the words "In the beginning God." This phrase fits perfectly on the 1st line (the beginning) of the 340 cipher, with the 15th, 16th and 17th characters uncannily similar to the word GOD (the O in half phase just like the image on the stamp). 

But this wouldn't be the only correspondence that suggested the 340 cipher was designed as a puzzle rather than a 408 style message, If the paradice and slaves connection does exist between the 340 cipher and 'Halloween' card, then it makes more sense that the design of paradice and slaves was created in the 340 cipher first, and the 'Halloween' card was to "clue us in". If not, then the observation is just happenstance.
​If the 340 cipher doesn't actually contain a message, it will never be broken, and paradoxically will remain unsolved despite no solution being possible. 
The cipher has many other issues- in that, the Zodiac Killer may have had 'cipher three' formulated or drafted before he designed 'cipher two', to enable the interconnectivity between both. He had to think forwards to create backwards.
If we assume the 340 cipher has a solution and therefore a key (no matter how complex), then one may assume the Zodiac created the key, then created the message, and then applied the message to the key, so as to encrypt it. If this were the case, we must believe that the 'near Zodiac' that emerged on line 20 was by sheer chance. We would also have to believe, that had he crafted 'cipher three' completely independent of 'cipher two', with no intention of connecting both, then the following observations also happened completely by chance.

​Although covered many times before, the following will help explain the conundrum. 
Because the '13 Symbol' cipher was thirteen characters in total (half the alphabet) and began with an A and ended with an M, it was considered that by placing the first half of the alphabet alongside the '13 Symbol' cipher and numerically counting the difference between the columns, something may emerge- It did.
For example: C to N produces a difference of 11, whereas B and E produces a difference of 3. Non alphabetical symbols cannot produce a difference, so a zero is inserted. The resulting numbers produced have been color coded. The red section is before the first circled 8, the green section is after the last circled 8 and the blue section spans the first and last circled 8. Notice the perfect symmetry. The red and green numbers are identical read forwards or backwards, and the blue numbers again read identically in either direction, producing a mirror image.
An equally symmetrical pattern was created using the identical technique, when placing the correct spelling of Zodiac alongside the 'near Zodiac' on line 20 of the 340 cipher. 
Furthermore, the three 0's and three 8's created, can be combined and carried forward onto his '13 Symbol' cipher, which seemingly is what he did.
It is also apparent on the '13 Symbol' cipher, that either side of the three circled 8's are the Zodiac crosshairs and an inverted Aries symbol, also present on either side of the 'near Zodiac' on the final line of the 340 cipher. So, the author has effectively carried eight symbols from one cipher to another.
The point being, that when the Zodiac Killer sat down at his desk and began to create a unique key for his 340 cipher, into which he was to place his message, it accidentally created the 'near Zodiac' on the 20th line, accidentally created the correlation between 'near Zodiac' and Zodiac to produce three circled 8's, accidentally created the symbols either side of 'near Zodiac,' that fully or in part, carried forward to the '13 Symbol' cipher in the correct position, and accidentally created symmetry in both instances. Or, the Zodiac crafted the '13 Symbol' cipher before or alongside the 340 cipher, which I would argue nobody believes.
The Zodiac Killer may have began his 340 cipher key from the bottom first, deliberately allocating specific letters in his message to create the 'near Zodiac' characters and continuing from there. But, if the interconnectivity exists between the 340 cipher and '13 Symbol' cipher, he effectively began with 'cipher three' first and worked backwards, and worked forwards with the words ​paradice and slaves from the 408 cipher. 

​The Zodiac may have presented us with a fictitious negro male on August 4th 1969, who by inference, provided us with some valuable information about the Zodiac Killer driving his brown car by the payphone at Springs and Tuolumne. Was this a red herring of a clue, much like the correction on line 6 of the 340 cipher.
It can be clearly seen on the left, that the Zodiac Killer was conscientious enough to correct an alphabetical K to a reversed K on line 6, even though spelling correctly was never much of an issue with the Zodiac Killer. To validate that this was a genuine mistake, he made sure that the original K had not been fully obscured. This may give the impression it is easy to mix up your K's when implementing your encrypted text. Or maybe this is what he wanted us to believe. Who in their right mind would correct a fake cipher? Therefore it must be genuine.
Did the Zodiac Killer implement this correction, conveniently leaving the blacked out character still visible (and just reversing it), to give us the impression that the 340 cipher is undeniably genuine. Was this move just another red herring, to again validate something that never was. 
Alternatively, the final line of the 340 cipher may contain just a part message, yet incomplete, bearing in mind that many believe the '13 Symbol' cipher may contain some form of a name. The 340 cipher may end with: "the Zodiac is".... to be continued on the next cipher. The anticipation of the newspapers and readers alike, for the sequel to be released, would be a Zodiac dream.
The Zodiac Killer may have been pushing us in the right direction on October 27th 1970, but his attempt at revealing the workings of the 340 cipher may have begun far earlier, on December 16th 1969- just 38 days after his 'so called' masterpiece- in which he would be claiming a potential 38 more victims.
The December 16th 1969 'Fairfield' letter, mailed to the San Francisco Examiner, has been considered dubious Zodiac correspondence, however, it may have been Zodiac's first foray into revealing the mechanics of the 340 cipher, albeit using a rudimentary code as a tool. 
Clearly, the Zodiac must have known that offering just five different symbols in a code of nine is open to many different interpretations, and hence practically unsolvable. Therefore, one could suggest this wasn't his intention- he was simply teasing us with the mechanics of how the 340 cipher was designed, by using a rudimentary diagram based on the Tim Holt comic- and something he would expand upon nearly a year later.
One can see how he uses the Zodiac symbol around the crosshairs in the December 16th 1969 'Fairfield' letter code, implying a uniformity of message, but aligns five symbols as an introduction to this design. This marries perfectly with 'Death By Gun', 'Death By Knife', 'Death By Fire' and 'Death By Rope.' Death is the introduction, following by the methods of death around the crosshairs. This is exactly what he offered us on October 27th 1970, when he placed the methods of death in the four quadrants of the bisecting Paradice and Slaves.  Here is a representation. 

Another Fairfield letter was mailed prior to this correspondence on December 7th 1969, mailed to the San Francisco Chronicle. Was the Zodiac Killer highlighting pertinent sections of the 340 code in as little as one month after his November 8th 1969 'Dripping Pen' card and cipher, negating the idea he could resist the temptation of giving us clues to its design.
The final offering to the mechanics of the 340 cipher may have come with his final confirmed correspondence- that of the 'Exorcist' letter mailed to the San Francisco Chronicle on January 29th 1974. ​         

The symbols at the foot of the 'Exorcist' letter were rearranged by Kevin Robert Brooks to reveal the words "To Kill". The message would then read "If I do not see this note in your paper, I will do something nasty, which you know I'm capable of doing...To kill."  
This threatening message was very similar to the trinity of communications that began the Zodiac's letter writing campaign on July 31st 1969, where he stated "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."  
In both the 'Exorcist' letter and July 31st communications the author would threaten "to kill'- as he would in the decoded 408 cipher. This is not particularly unusual for a serial murderer, but linking the unarranged symbols on the 'Exorcist' letter to the 340 code may connect yet another communication to the design of the cipher.
Key features of the 'Halloween' card, '13 Symbol' cipher, Fairfield communications and 'Exorcist' letter can be found in the 340 cipher, suggesting the Zodiac Killer was constantly pushing us towards the design of the 340 puzzle.
The following presentation will show a perceived correlation of the 'Exorcist' letter symbols to the only corrected section of the 340 cipher.

​​In the image on the left I have moved the two symbols on the extreme left of the 'Exorcist' letter to the right side as shown, without altering their position on the vertical axis. Then I have turned the extreme right symbol on the 'Exorcist' letter 90 degrees clockwise to form the new arrangement, shown in the bottom left image. This can now be compared to certain characters on the fifth, sixth, seventh line of the 340 cipher. The area in the proximity of the corrected sixth line.
Five of the six characters on the 'Exorcist' letter now bear a noticeable similarity to this area of the 340 cipher.
Did the Zodiac Killer sit down to create a uniform and continuous message using a code key in the 340 cipher, just like the message contained within the 408 cipher? If so, then the above findings were all created accidentally and unintentionally by the killer.
He placed an intersecting symbol at the center of the 340 cipher (+ sign), with two dashes at the periphery of the center line, to create the illusion of intersecting crosshairs.
Paradice and Slaves (uniformly of 17 characters) was created as a viable possibility bisecting the 340 cipher along the X and Y axis, along with "RAD" and "LAV" on the intersection of the cipher. The word "BY" (horizontally) was present in all four quadrants of the cipher. The 'near Zodiac' allied with the correct spelling of Zodiac on the 20th line produced the symmetry of three circled 8's. Using the identical technique and placing half the alphabet alongside the '13 Symbol' cipher, yet again, perfect symmetry was observed.
The three circled 8's, along with the symbols either side, all carried forward from the second cipher to the third cipher, and the 'Exorcist' letter symbols aligned with the corrected sixth line of the 340 cipher. This of course all happened by chance and the Zodiac Killer knew nothing about it.  
This would indicate that the Zodiac Killer had deliberately placed Paradice and Slaves into the 340 cipher, to which he would give us a clue one year later. The machinations of the '13 Symbol' cipher were most likely constructed in the mind of the killer before November 8th 1969, as to create a continuity between the two ciphers. The idea therefore, that the author of all these communications could interweave these designs together and still create a rambling uniform message to co-exist alongside them within the 340 cipher, would probably be a step too far.
The idea of a killer who sat down one evening to write a rambling 340 character message, to which he enciphered using a code key, who would then accidentally and inadvertently create so many by-products in his cipher without his knowledge, seems rather fortuitous. The Zodiac seemingly couldn't resist showing us the workings of his great masterpiece, and would eventually tell us that the 340 code was "no cipher", by giving us a portion of its true design in the 'Halloween' card on October 27th 1970. However, it's far more fun chasing chasing a real cipher, that will long continue for another 50 years.      

Here we will revisit an article published by the San Francisco Examiner on October 22nd 1969, in which Professor D.C.B. Marsh, president of the American Cryptogram Association laid down a challenge to Zodiac. The words he chose to use in this article may be the bedrock to much of the subsequent Zodiac communications, beginning with the 340 cipher, mailed only seventeen days after the San Francisco Examiner article. Here are the crucial extracts from that article.
'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, which will truly and honestly include his name." It is difficult to believe that Zodiac, an avid reader of the newspapers, could resist such a challenge, particularly as he had promised to reveal his identity in the 408 cipher two months earlier, but failed to do so.  

The key section to note in the challenge by Professor D.C.B. Marsh is: "I invite Zodiac to send The American Cryptogram Association a cipher code, which will truly and honestly include his name."
Seventeen days later, the Zodiac Killer duly obliged with the November 8th 1969 340 cipher. Could this cipher have included the killer's name, but not in the format envisaged by Professor D.C.B. Marsh?
In a previous article entitled 'Zodiac Admitted 340 Not a Real Cipher' we examined the idea that the 340 cipher was inextricably linked to the Zodiac's 'Halloween' card, mailed on October 27th 1970. One can notice that the word "By" is located in each of the four quadrants of the 340 cipher. The author of the cipher also placed the letters F and K adjacent to one another no less than seven times (situated in each quadrant). But of particular interest was the corrected section on the sixth line of the 340 cipher, where the author chose to scrub out a forward facing K and replace it with a backwards K, elevated above the blacked out section.
The Zodiac Killer was known for numerous spelling errors in his communications, so why was it seemingly imperative to correct this one mistake? Was this correction crucial to the interpretation of the cipher, or was he drawing our attention to the letters in this section of the cipher? Are the F and K characters the initials of the Zodiac Killer?
This observation carries little merit on its own, so to bolster any argument for the initials of the Zodiac Killer being present in the 340 cipher, we have to explore the rest of his communications, particularly from around the time of the 'Halloween' card, in which we suggested was his admission that the 340 was unfortunately "no cipher". 
Linking the 'Halloween' card and 340 cipher through a Tim Holt comic book and explaining to us that the solution was "sorry no cipher." left us with the possibility that the 340 cipher was just a collection of puzzles, in which may have contained his name. The Zodiac Killer "wouldn't dare, as he claimed in letters to the newspapers, to reveal his name in the cipher to established cryptogram experts", but he may have given us the abridged version.
We now enter the crucial phase of Zodiac communications, from the '13 Hole' postcard mailed on October 5th 1970, to the 'Exorcist' letter mailed on January 29th 1974. This critical period of four consecutive communications, is probably key to understanding the message the Zodiac Killer was trying to push. That the 340 was "sorry no cipher."      

In the '13 Hole' postcard the Zodiac Killer stated "There are reports city police pig cops are closeing in on me. Fk I'm crackproof. What is the price tag now?"
This section of pasted letters was placed upside down. The question one should be asking is 'what is the purpose behind this'. If its significance had no relevance to the actual postcard, did it have relevance to another communication.
The wording "FK I'm crackproof" could indicate that the killer thought he was immune from capture, however, it could also be a reference to his 340 cipher once again. The word "crackproof" is something that is unable to be cracked.
The 340 cipher would certainly be impervious to cracking, and certainly resistant to the attempts of The American Cryptogram Association had the killer devised a cipher not of conventional understanding, of which Professor D.C.B. Marsh was hoping when he laid down the challenge. The F and K text being flipped on the '13 Hole' postcard reminds one of the flipped K (next to F) on the only corrected portion of the 340 cipher. If FK were the Zodiac Killer's initials, then he certainly could be declaring that he was crackproof. 
​Professor D.C.B. Marsh stated  "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." However, the Zodiac Killer could give his name in the form of initials without any fear of revealing his identity, and without risking his immediate capture. This may have manifested itself when he mailed his following cipher on April 20th 1970, when he opened with the gambit "This is the Zodiac speaking. By the way have you cracked the last cipher I sent you. My name is...."  The code placed underneath was likely an immediate rebuttal to this question. 

All he is probably doing, is stating "My name is FK," and once again telling us he is crackproof, just like the '13 Hole' postcard, which would be mailed five and a half months later. The phrase "FK I'm crackproof" fits perfectly in circular formation within the '13 Symbol' cipher- which itself contains a series of circled 8's. Structured in this fashion, the F and K yet again align, as does the K and M in both the cipher and phrase. 
Continuing with our four consecutive communications from October 5th 1970 onward, we now have the October 27th 1970 'Halloween' card promising to yet again reveal his name: "I feel it in my bones, You ache to know my name, And so I'll clue you in." Again we feel disappointed only to see the word "Boo" on the card inner- but we know the Zodiac Killer isn't going to make this a conventional and straightforward offering. He offers us the phrase "sorry no cipher," but can we find his name or initials within this communication. This is where it gets more difficult, nevertheless, we are aware that within the '13 Hole' postcard he reversed or flipped the text containing "FK I'm crackproof" and he flipped the K (next to the F) on the sixth line of the 340 cipher. So the obvious conclusion, is to look for flipped or reversed text within the 'Halloween' card.  

The only place that F and K exist within one word on the 'Halloween' card, is in the word "knife." either side of the reversed letter N.
If we flipped the reversed N back to its appropriate position, the F and K of "knife" would be reversed yet again.
Now let us turn our attention to the peculiar configuration at the foot of the card inner. It would be extremely satisfying for the 'Halloween' card to read "I feel it in my bones, You ache to know my name, And so I'll clue you in... FK,"- so that is what we will create, by manipulating this card to read whatever we want it to.
The strange symbol, reading it as true as possible, appears like a number 7, followed by four dots and the letter F.
7+4=11=K (followed by F).
Without further ado, we shall move on to the next confirmed Zodiac communication on March 13th 1971, in which the Zodiac stated "This is the Zodiac speaking. Like I have allways said, I am crack proof. 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. I do have to give them credit for stumbling across my riverside activity, but they are only finding the easy ones, there are a hell of a lot more down there. The reason I'm writing to the Times is this, They don't bury me on the back pages like some of the others."
You will notice that the Zodiac Killer refers to "crackproof" once again, parroting his October 5th 1970 communication five months earlier. However, he doesn't just state he is crackproof, he reminds us that he has always been telling us he is crackproof, and quite possibly we just haven't got the message.

Roll on the January 29th 1974 'Exorcist' letter, signed "yours truley," nearly three years later, giving us our final installment of FK contained within the array of symbols at the foot of the letter. 
On this occasion he mirrors the sixth line of the 340 cipher by elevating the K above the letter F, and to its left. In fact, five characters from the Exorcist letter can be found in and around the corrected sixth line of the 340 cipher, as shown here in a previous article. This was possibly the fourth consecutive communication inferring an FK link and the suggestion that the author was indeed "crackproof."  
Was this a persistent and deliberate attempt to be true to the challenge laid down by The American Cryptogram Association and Professor D.C.B Marsh, by inserting his name (albeit initials) into the 340 cipher and subsequent communications, or just a case that my mind is F@@Ked after six exhausting years of looking for patterns where none exist.

The following observations are crafted with little, to no knowledge of cryptology, in respect to the validity or otherwise of the Zodiac 340 cipher. The cipher has withstood nearly 50 years of computer assaults, as well as some of the greatest minds in the field of codebreaking, yet as of writing, nothing has been officially verified as a solution despite many claims to the contrary.
The criteria for a definitive solution to the 340 cipher, is not when one person or few believe a solution has been achieved, it is when there is overwhelming consensus across the board, removing subjectivity from the equation.   
If the 340 cipher doesn't actually contain a message, it will never be broken, and paradoxically will remain unsolved despite no solution being possible. Having examined this cipher innumerable times, the only solution I can come to- is it has no solution.
This revolves around two key issues: In that, the Zodiac Killer may have had 'cipher three' formulated or drafted before he designed 'cipher two', to enable the interconnectivity between both. He had to think forwards to create backwards.
If we assume the 340 cipher has a solution and therefore a key (no matter how complex), then one may assume the Zodiac created the key, then created the message, and then applied the message to the key, so as to encrypt it. If this were the case, we must believe that the 'near Zodiac' that emerged on line 20 was by sheer chance. We would also have to believe, that had he crafted 'cipher three' completely independent of 'cipher two', with no intention of connecting both, then the following observations also happened completely by chance.     

Although covered many times before, the following will help explain the conundrum. 
Because the '13 Symbol' cipher was thirteen characters in total (half the alphabet) and began with an A and ended with an M, it was considered that by placing the first half of the alphabet alongside the '13 Symbol' cipher and numerically counting the difference between the columns, something may emerge. It did.
For example: C to N produces a difference of 11, whereas B and E produces a difference of 3. Non alphabetical symbols cannot produce a difference, so a zero is inserted. The resulting numbers produced have been color coded. The red section is before the first circled 8, the green section is after the last circled 8 and the blue section spans the first and last circled 8. Notice the perfect symmetry. The red and green numbers are identical read forwards or backwards, and the blue numbers again read identically in either direction, producing a mirror image.
An equally symmetrical pattern was created using the identical technique, when placing the correct spelling of Zodiac alongside the 'near Zodiac' on line 20 of the 340 cipher. 
Furthermore, the three 0's and three 8's created, can be combined and carried forward onto his '13 Symbol' cipher, which seemingly is what he did.
It is also apparent on the '13 Symbol' cipher, that either side of the three circled 8's are the Zodiac crosshairs and an inverted Aries symbol, apparent either side of the 'near Zodiac' on the final line of the 340 Cipher. So, the author has effectively carried eight symbols from one cipher to another.
The point being, that when the Zodiac Killer sat down at his desk and began to create a unique key for his 340 cipher, into which he was to place his message, it accidentally created the 'near Zodiac' on the 20th line, accidentally created the correlation between 'near Zodiac' and Zodiac to produce three circled 8's, accidentally created the symbols either side of 'near Zodiac,' that fully or in part, carried forward to the '13 Symbol' cipher in the correct position, and accidentally created symmetry in both instances. Or, the Zodiac crafted the '13 Symbol' cipher before the 340 cipher, which I would argue nobody believes.
The Zodiac Killer may have began his 340 cipher key from the bottom first, deliberately allocating specific letters in his message to create the 'near Zodiac' characters and continuing from there. But, if the interconnectivity exists between the 340 cipher and '13 Symbol' cipher, he effectively began with 'cipher three' first and worked backwards. However, this doesn't seem the likeliest of answers. The alternative, one could argue, is that the 340 contains only his pseudonym and nothing more.

The Zodiac may have presented us with a fictitious negro male on August 4th 1969, who by inference, provided us with some valuable information about the Zodiac Killer driving his brown car by the payphone at Springs and Tuolumne. Was this a red herring of a clue, much like the correction on line 6 of the 340 cipher.
It can be clearly seen on the left, that the Zodiac Killer was conscientious enough to correct an alphabetical K to a reversed K on line 6, even though spelling correctly was never much of an issue with the Zodiac Killer. To validate that this was a genuine mistake, he made sure that the original K had not been fully obscured. This may give the impression it is easy to mix up your K's when implementing your encrypted text. Or maybe this is what he wanted us to believe. Who in their right mind would correct a fake cipher? Therefore it must be genuine.
Did the Zodiac Killer implement this correction, conveniently leaving the blacked out character still visible (and just reversing it), to give us the impression that the 340 cipher is undeniably genuine. Was this move just another red herring, to again validate something that never was. 
Alternatively, the final line of the 340 cipher may contain just a part message, yet incomplete, bearing in mind that many believe the '13 Symbol' cipher may contain some form of a name. The 340 cipher may end with: "the Zodiac is".... to be continued on the next cipher. The anticipation of the newspapers and readers alike, for the sequel to be released, would be a Zodiac dream.