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

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

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

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

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

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

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

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

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

Many attempts have been made to conclusively link the Riverside murder of Cheri Jo Bates on October 30th 1966, along with the accompanying communications, to the Zodiac Killer. The three 'Bates' letters, on April 30th 1967, ended the Riverside chapter, with the three July 31st 1969 letters to the San Francisco Chronicle, San Francisco Examiner and Vallejo Times-Herald, beginning the Zodiac chapter. But is the hidden identity contained within the 408 cipher (if it exists) somehow connected to the hidden author of the November 29th 1966 'Confession' letter? It is paramount to make a distinction between name and identity when attempting to formulate any cohesive link between the Confession letter and 408 cipher, because the Zodiac Killer claimed he wouldn't give us his name in the decoded 408 cipher, but did claim it would reveal his identity.

​When we take a close look at the decoded 408 cipher, it can be argued that he made a fundamental error when he encoded his original message, accidentally omitting the word "people" in the ciphertext. This is explained in 'The 18 Unsolved Characters [Pt3]'  This effectively created a shortfall of 6 characters in his 408 cipher, which had he not done, would only have left 12 unsolved characters at the end of the message. In view of the Bay Area murderer identifying himself as "Zodiac" just four days later, it was considered that his impatience may have compelled him to reveal his identity earlier than he would have liked, and "Zodiac" was integral to his identity in the 12 characters at the end of the 408 cipher. The hidden identity, therefore, the "Zodiac Killer". 

Had the 408 cipher 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", and the last 12 characters contained his identity, then by extension, we should be looking backwards to Riverside for the previous time he used a form of cryptic or hidden message. The only letter that contained such an instance, was the November 29th 1966 letter beginning "The Confession by - - - - - - - - - - - -".  This contained 12 underscores of, presumably, the hidden name or identity of the killer. For those believing a connection from Riverside to the Bay Area, the potential murderer of Cheri Jo Bates may have cloaked his identity behind 12 underscores in the Riverside 'Confession' letter and 12 characters in his communication with the San Francisco Chronicle on July 31st 1969.  The 'Bates' letters correlated via a trinity of letters, whereby the 'Confession' letter correlated through the identity of twelve.

This analysis fundamentally fails to successfully bridge the divide from Riverside to the Bay Area, as many arguments have before - and the connection between the murder of Cheri Jo Bates and associated communications, to the Zodiac Killer, will remain a hot button topic for many years to come no doubt - but the search goes on.

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.
​
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.
​
The author had just switched from cipher 2 to cipher 3 (see below), which may have instigated the error.
​
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]

It seemed rather fortunate that the 'Halloween' card mailed on October 27th 1970, if designed totally independently to the 340 cipher, that Paradice and Slaves could be found perfectly bisecting the 340 cipher, 17 by 17 characters. Not to mention the word "By" being found in all four quadrants. This is discussed in more detail in the article 'The Illusion of the 340 Cipher.'  
The 'Halloween' card was almost certainly highlighting the Lake Berryessa attack on Bryan Hartnell and Cecelia Shepard, tied up with rope (plastic clothesline) and brutally stabbed sixteen times by the Zodiac Killer. The phrase "peek-a-boo you are doomed" referencing the children's game peekaboo, where 'hiding behind that tree' is sometimes added. This would also be the second time "by knife" would be used - linking the 'Halloween' card to the Volkswagen Karmann Ghia of Bryan Hartnell.
Since these two 'methods of death' (rope and knife) were instrumental to the attack on the young couple, we will focus on Paradice, Slaves, By Knife and By Rope. 
On the 'Halloween' card it is apparent that "By" is written vertically for "knife" rather than horizontally, as displayed by the other 'methods of death'. Could this be a sinister inference to a knife being driven downwards and the predominant focus of this card?   

If we color in the five characters underneath the 'Y' in the bottom left quadrant of the cipher, as is portrayed on the 'Halloween' card, it can be seen that the 'right facing V' would represent the 'E' of knife.
If we  color in the four characters underneath the 'B' in the bottom right quadrant of the cipher, as is portrayed on the 'Halloween' card, it can be seen that the 'right facing V' would represent the 'E' of rope.
To complete the word Paradice and Slaves a 'left facing V' had to be found in the last section of both words for parity. In this instance a 'left facing V' represented the letter 'E'.
When the Zodiac Killer introduced his 408 cipher in the July 31st letters, he stated "Here is part of a cipher" or "Here is a cyipher." When challenged to design another cipher by D.C.B. Marsh in the San Francisco Examiner on October 22nd 1969, the 340 cipher arrived just over two weeks later. The article was entitled 'Cipher Expert Dares Zodiac to Tell Name'. Bearing in mind that the 340 cipher began with "Her," could it have started with "Here is a cipher" or "Here's a cipher" (to marry with the 'P' of Paradice) in direct response to cryptographic expert D.C.B. Marsh.
There are 10 'left or right facing' V's in the entire 340 cipher. If the latter hypothesis was correct, then at least 50% of these would be represented by the letter E, in respect of Here, Paradice, Slaves, Rope and Knife.  

We know the Zodiac Killer mailed his first three letters simultaneously on July 31st 1969, but what inspired him to design a trinity of cryptograms that when combined formed an almost complete and uniform message. It is likely he split the cipher into three parts for maximum newspaper coverage, however, we know little of what inspired him to design the codes in the first place.
The 'Zodiac Killer' pseudonym may never have existed had it not been for the skepticism of Vallejo Police Chief Jack E Stiltz, who insisted the three time murderer send more details to prove he was the 'cipher killer'. It was reasoned that something Zodiac read in the Sunday August 3rd 1969 San Francisco Examiner & Chronicle inspired him to repackage himself from "the murderer" to "the Zodiac". So, what drove the killer of David Faraday, Betty Lou Jensen and Darlene Ferrin to include a cryptogram alongside his deadly deeds and threats. The short answer is, nobody knows for sure- but we do know it took the Lake Herman Road double murderer just over seven months to finally begin his letter writing campaign. Was the killer always planning to kill again and write to the newspapers, or was it the extensive press coverage that inspired him to rise to the picture being painted of him. 
It seemed Detective Sergeant Leslie Lunblad beat a lone furrow in the pursuit of the murderer, but he was ably assisted throughout by many agencies, including the Criminal Investigation Bureau in Sacramento, Vallejo Police Department, Napa and Sanoma County sheriff's departments and Sergeant Jack Richard Oller, an investigator in the Fairfield office of the sheriff's department.  Jack Oller moved to Oakland, California in 1929 and served in the U.S. Army as a combat engineer in Europe. In 1978, he retired from the Solano County Sheriff Department with the rank of lieutenant.
Along with the Zodiac murder of Paul Stine on October 11th 1969 and the November 21st 1969 San Jose letter and cryptogram, we effectively had the entire shopping list of threats tabled in the 'Fairfield' letter, mailed on December 16th 1969. His threat of 'this state is in trouble..I will go for the Goverment life' may be traced back to a Sunday Times-Herald article on March 30th 1969, in which these law enforcement agencies were pivotal in the search for the Lake Herman Road murderer, including Sergeant Jack Oller. The Zodiac Killer's threat on police in the 'Fairfield' letter centered around Fairfield, Sacramento and Oakland. 
The inspiration behind the July 31st 1969 letters and cryptogram is difficult to ascertain, but often with the Zodiac Killer throughout it was something he read that triggered a response, such as the 'Debut of Zodiac' and 'Bus Bomb' letters.
The Sunday Times-Herald article on March 30th 1969 may or may not hold the answers, however, it was published four months prior to the July 31st trinity and did contain some noteworthy passages. Whether these were the trigger for the murderer to begin his letter writing campaign is pure speculation, but in the absence of alternatives it was worth considering.  
Here is the newspaper article in full:     

The youth, a scalor at Vallejo High, planned to make teaching his career. He was extremely active in Scouting, and was a member of the Interact Club at the high school.
"Last summer, he discovered girls" Mrs Faraday reminisced "but he hadn't done much dating- for one thing he could use the car only when I didn't need it to go to work." She is employed in the passenger reservations department at Travis Air Force Base. She said that when he did take the car for a date "he was good about observing curfews" (12.30 on Friday nights). "So I didn't think a thing about it that night. I was asleep when the phone rang at 3 am."
Mrs Faraday conversed with total composure, although the wounds haven't healed and won't. The same was true of the Jensens. Nothing in his 21 years as an army officer had prepared Lt Col. Verne Jensen for the shock of his younger daughter's death, however. He retired in 1963, decided to remain in Vallejo and now is employed as supply officer for the General Services Administration in San Francisco. The Jensens, with their elder daughter, Melodie, live at 123 Ridgewood Ct. " I don't feel vindictive" he mused "but I am apprehensive. I feel some nut is on the loose."
His words could have been uttered by Mrs Faraday, who said her principal concern that the killer be found was not based on vengeance but on her fears there may be further victims. "And, he'll find it easier the next time."
She said the other three Faraday children Debra, Robert and Steven "have handled the situation very well, I think. Presumably they have long and happy lives ahead of them, and they've got to live them."
The Jensens' lives remain clouded by the tragedy. "We'd like to have her back" Mrs Jensen said wistfully. "It took a lot to bring her this far."
At Hogan High Betty was an excellent student, a junior, she was hopeful of winning an art scholarship and she worked extremely well in several forms, some of which were displayed as I talked to the family. All three shook their heads negatively when asked if they had any ideas to the perpetrator. "We know he's a nut, but what kind of nut" Mrs Jensen replied. She added she was dubious about anything worthwhile could be gained in once again turning the spotlight on the murder case. "But we'll do anything we can to help" she declared.
As for the investigation's progress, Lublad said there has been considerably more than might be gleaned from news accounts of it. "If I talk to a suspect, I'll know positively whether he was there that night" he said cryptically. Beyond that, he would not comment. ​​

It is not difficult to cherry-pick certain phrases and words to fit ones agenda, however, we must consider that the murderer of David Faraday and Betty Lou Jensen likely read this article, and was buoyed by the description of his exploits as a "horrifying crime that may very well be the most celebrated murder mystery currently under investigation in California."
David Faraday's mother summed up her fears: "who said her principal concern was that the killer be found, not based on vengeance but on her fears there may be further victims. "And, he'll find it easier the next time."  
She wouldn't have to wait long for the killer to live up to her fears, promising he would "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."  
Detective Sergeant Les Lunblad's support may too have not gone unrecognized, with his assistance from a "score of law enforcement agencies in the state," including Sergeant Jack Richard Oller and the Fairfield Office.
If this newspaper article was the last major feature regarding the Lake Herman Road slayings, before the killer began his July 4th 1969 attack on Michael Mageau and Darlene Ferrin at Blue Rock Springs, then it is rather unusual that the ​Sunday Times-Herald article on March 30th 1969 would finish with the thoughts of Detective Sergeant Les Lunblad:in such a manner:
"If I talk to a suspect, I'll know positively whether he was there that night" he said cryptically.
Four months later, the murderer stated "I will not give you my name because you will try to slow down or stop my collecting of slaves for my afterlife," and he too said it cryptically.    

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.      

As has been pointed out by many intelligent posters, the Zodiac Killer never actually claimed any crimes that would later be attributed to another criminal, because he was simply too vague when insinuating his attachment to these said crimes. Two notable examples would be the June 19th 1970 murder of Officer Richard Radetich and the October 30th 1966 stabbing of Cheri Jo Bates- the latter of which he only 'suggested' in March of 1971, stating "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". 
There is without doubt some interesting connections between the Zodiac and Riverside, in particular, the trinity of consecutive communications from April of 1967, to the three July 31st 1969 letters that began the letter writing campaign by the Zodiac Killer. It is therefore understandable that many observers want to interpret the symbol at the foot of the Bates letters as an alphabetical Z, to bridge the connection between the Bay Area and Riverside, and bolster an argument for it. However, was this symbol seriously considered to be an alphabetical Z before the arrival of Zodiac just over two years later, or was it just a convenient reappraisal.   

Here are the two prominent Z like characters from the foot of the Bates letters, mailed to the Riverside Press Enterprise and Riverside Police Department. It is easy to want these to be an alphabetical Z, but unless the Zodiac performed a near identical error on two occasions, or just happened to have aligned his writing paper over an uneven writing surface in both instances, then there is little reason to believe these two characters are a Z.
Additionally, if these two characters were a Z (representing Zodiac), then why not just write 'Zodiac' at the foot of the Bates letters.   
Two years later, on July 31st 1969, the killer we now know as Zodiac announced himself to the world, when he wrote to the San Francisco Chronicle, San Francisco Examiner and Vallejo Times-Herald newspapers, but yet again, despite supposedly masquerading as the Zodiac Killer, he was still apparently reticent to reveal his pseudonym to the world, only introducing himself as "the murderer of the 2 teenagers last Christmass at Lake Herman + the girl on the 4th of July." For a egotistical murderer so bold, he seemed rather reluctant to reveal his identity. Had Vallejo Police Chief Jack E Stiltz not questioned the July 31st 1969 letter writer in the August 3rd 1969 San Francisco Examiner, stating he was "still not convinced the letters and codes were written by the actual killer, and urging the writer to send more letters, with more facts to prove his connections to the crimes," then the August 4th 1969 'Debut of Zodiac' letter would not have been written by the killer. In other words, the 'Zodiac Killer' would still not have been born. How can we reconcile this reluctance to announce the pseudonym 'Zodiac' to the world, with the fact he had supposedly concocted this pseudonym by the time of the Bates letters in April 1967.             

Many people have stated that the Zodiac Killer acquired the pseudonym 'Zodiac' and the crosshairs symbol from the Swiss watchmaker, as they appear together under one banner.
"In 1882, Ariste Calame founded a workshop for the production of special watches in Le Locle, Switzerland. The original name of the company was Ariste Calame and would later become Zodiac. The name "Zodiac" was used early but was not registered until 1908. The founder's son, Louis Ariste Calame, was sent to watchmaking school, and then began to participate in the business in 1895, and took over the business that year." Wikipedia.
If the Zodiac Killer was inspired by a watchmaker, then one has to ask the question- why did he only use the crosshairs in his three July 31st 1969 letters and seemingly abandon the name Zodiac, if an advertisement such as the one on the right was the trigger. Again, he only introduced himself as the Zodiac Killer four days later when the 'Debut of Zodiac' letter arrived at the San Francisco Examiner, and even that wouldn't have arrived if the killer had not been prompted by Vallejo Police Chief Jack E Stiltz..
The idea of gunsight crosshairs proposed by many, may be the likely inspiration for the murderer of three young people at Lake Herman Road and Blue Rock Springs Park. The standalone crosshairs at the foot of each of the July 31st 1969 letters appear to be the logical conclusion to the threat that preceded it.
The San Francisco Chronicle, for example, finished with an ominous threat: "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." So it isn't particularly illogical that this threat may be followed by a "target" sign or the crosshairs of a gun, without the need for the pseudonym Zodiac or a connection to a famous watchmaker. The killer is simply signing off his letters by indicating he has more people in his sights.
If there ever was the perfect opportunity to announce himself to the American people under the name Zodiac, this was the perfect time- in accompaniment with a trinity of letters and his opening coded message, in which he actually promised to reveal his identity. However, this opportunity was spurned. The reason for this, one could argue, was the pseudonym Zodiac had not been conceived by the killer at this juncture.
The San Francisco Sunday Examiner and Chronicle of August 3rd 1969 opened with the lines "A self-accused killer failed to keep a threat of mass murder here, but there was no slackening of tension or mystery caused by the warning. The police department telephone system was clogged at times by anxious callers asking if the "cipher killer" had been caught."  In this short snippet of text probably lay the inspiration behind the pseudonym Zodiac- as he was not prepared to be labelled the "cipher killer" by anybody. This was the push he needed. The following day the Zodiac was etched into the minds of police and newspapers alike, and has remained so for nearly half a century.    

The answer to the origin of the pseudonym Zodiac likely sits within the pages of the San Francisco Sunday Examiner and Chronicle of August 3rd 1969. 
Somebody with access to newspaper archives may be able to discover the inspiration behind America's most infamous serial killer.
One possibility could be the Zodiac horoscope section, or an advertisement such as the one above for Zodiac watches. Had the latter been the case, it could be strongly argued that the Zodiac Killer was extremely fortunate in signing off his three July 31st 1969 letters with  threatening crosshairs, only to discover they were also the symbol used by the Swiss watchmaker only three days later.
On the contrary, had the Swiss watchmaker been the original inspiration behind the Zodiac's pseudonym and logo, then why did he fail to introduce the name "Zodiac" in his July 31st 1969 letters. He delayed the introduction until his August 4th 1969 letter to the San Francisco Examiner, in direct response to the San Francisco Sunday Examiner and Chronicle article of August 3rd 1969. Therefore, this newspaper had to be the driver behind the name Zodiac, not only because of his lack of affection for the "cipher killer" pseudonym, but because the name Zodiac probably lay somewhere within its folded pages.       

The Zodiac Killer did not mail the three July 31st 1969 letters to the San Francisco Examiner, San Francisco Chronicle and Vallejo Times-Herald, although the murderer of Betty Lou Jensen, David Faraday and Darlene Ferrin certainly did. 
In the letter to the Chronicle, the author suggested that within the code he had mailed we would discover his identity.
He wrote "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." 
When the cipher was decoded a matter of days later, the code revealed "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." 
The killer of three assured us that his identity was concealed within the cipher, while all along, knowing the enciphered text would reveal that he was unprepared to give us his name. He was effectively equating his identity with his name, not with his pseudonym or other covert means of identifying him. That is probably because the assailant at Lake Herman Road and Blue Rock Springs was technically not the Zodiac Killer. The "Zodiac Killer" 'only' killed two people under the Zodiac pseudonym, that of Cecelia Shepard and Paul Stine.
As covered in a previous article 'Born on August 3rd,' it was argued that the killer had no "identity" or pseudonym to reveal to us before August 3rd 1969, because he hadn't yet assigned one to himself. Being called the 'code killer' or 'cipher killer' in the newspapers clearly didn't sit well with an ego-driven murderer. He had to give himself a pseudonym worthy of his perceived stature- hence, the "Zodiac Killer" was born. 

​The San Francisco Sunday Examiner and Chronicle of August 3rd 1969 opened with the lines "A self-accused killer failed to keep a threat of mass murder here, but there was no slackening of tension or mystery caused by the warning. The police department telephone system was clogged at times by anxious callers asking if the "cipher killer" had been caught."  The next day the killer would waste no time in introducing us to his new identity or pseudonym, opening with the line "This is the Zodiac Speaking." In other words, looking for his identity in the 408 cipher, in either the enciphered or decoded version would be a futile exercise, because he certainly wasn't going to reveal his real name, and it is extremely likely he had no identity or pseudonym at this juncture. Had he already attributed himself the pseudonym "Zodiac" prior to the July 31st 1969 letters, then this threefold barrage was the perfect time to announce the menacing "Zodiac" to the world, something he clearly failed to do. In fact, he could only muster the unoriginal "This is the murderer of the 2 teenagers last Christmass at Lake Herman + the girl on the 4th of July near the golf course in Vallejo."  
​Four days later however, he would be triggered into action by the lame 'cipher killer' pseudonym designated to him by the public and featured in the San Francisco Sunday Examiner and Chronicle of August 3rd 1969- He was in control, and as such, was not going to be labelled by anybody.
It was now a simple task of replacing one word in his introduction, from "This is the murderer" to "This is the Zodiac." 
This would have significant implications regarding the Riverside murder of Cheri Jo Bates on October 30th 1966, and in particular the three Bates letters. The idea that the symbol on these letters was an alphabetical Z indicating Zodiac would now be nullified, as the Zodiac pseudonym was 827 days in the making. 

Had the murderer opened up with the 340 cipher on July 31st 1969 rather than the 408 cipher, then the statement "in this cipher is my identity" would have had very few detractors, when just four days later a further communication arrived stating "This is the Zodiac Speaking." 
Comparing this introduction to the 'near Zodiac' at the foot of the 340 cipher would have left few in doubt this was deliberately placed, and indeed, he had concealed his identity in the cipher.
However, because the 340 cipher was mailed on November 8th 1969, it is often argued that the 'near Zodiac' may have fell out accidentally on his creation of the cipher- something that would likely never have been argued three months earlier. 
Therefore, if the Zodiac Killer did belatedly give us his identity or pseudonym in the second cipher, when we already knew it, one could suggest it has a secondary purpose, other than to be deciphered in exactly the same way as the other 334 characters.  
There is a growing perception that the 340 cipher is effectively a "bag of puzzles" rather than a continuous uninterrupted message, as many of its features can easily be linked or shown to compare favorably with other correspondences mailed by the Zodiac Killer. This man wasn't a Professor Moriarty style genius- so he either created a method of encryption so illogical, as to make the cipher unsolvable by the logical mind or computer created by logic, he created a mix of puzzles disguised within the cipher, or he created the perfect ghost cipher, to which he would eventually keep his promise by placing his identity within a cipher, but little else. 
Without identifying a key and demonstrating which communication it was found, then the '13 Symbol' and '32 Symbol' ciphers are simply too short to ever be proven as solved. In a previous article we highlighted a piece by Dave Oranchak, in which 46 consecutive alphabetical letters from the historical text of Edward Hyde, Earl of Clarendon, can be placed successfully into a portion of the 408 cipher. Dave Oranchak, the foremost expert on the Zodiac ciphers, commented on this "So, only one piece of text, from a vast collection of eleven billion pieces of text, fit into this chunk of cipher text. A one in eleven billion chance seems to suggest some significance. But don’t be fooled by this. Just because this rare event occurred, doesn’t mean it is anything more than a simple coincidence. If we didn’t already know the real solution to the 408, how do we know that this chunk of old and obscure text isn’t the correct solution?"  
Therefore, one can easily see the multiple solutions that can be harvested from these inadequately designed ciphers. The Zodiac Killer wasn't a genius, but he certainly wasn't a fool either, and must have known that the variability of the '32 Symbol' cipher, and lack of characters within the '13 Symbol' cipher were open to multiple solutions. This was probably part of the fun.
The man, eventually to become known as the Zodiac Killer, mailed the 408 cipher on July 31st 1969. This was a genuine cipher, decoded by Donald Gene and Bettye June Harden of Salinas, California, who both used homophonic substitution to identify the solution. The "cipher killer" or "code killer" would not have lived up to the name given him by the San Francisco Sunday Examiner and Chronicle on August 3rd 1969-  the "killer of codes" would have been far more suitable. 

The first part of this article has been copied from a previous offering, however, I have added some extra material to the foot of the article. ​
The following will be explaining in more detail the subconscious wording of the Zodiac Killer in his first three communications with the Bay Area newspapers, putting forward a compelling argument that the confirmed murderer of five was a resident of the Vallejo area. The Zodiac Killer would never willingly have given us his name or the locality of his residence, however, one could argue that had he revealed his home location without realizing it, then it is likely true. To do this, we have to examine closely the wording he chose on his July 31st 1969 letters using the present and past tense. Here is what the Zodiac stated on each communication:
Vallejo Times-Herald: "Here is a cyipher or that is part of one. the other 2 parts have been mailed to the S.F. Examiner + the S.F. Chronicle."
San Francisco Examiner: "Here is a cipher or that is part of one. The other 2 parts are being mailed to the Vallejo Times + S.F. Chronicle." 
San Francisco Chronicle: "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." 

You will notice the two San Francisco newspapers are being addressed in the present tense regarding the other two mailings, using the word ARE. While the Vallejo Times-Herald newspaper is being addressed in the past tense regarding the other two mailings, using the word HAVE. There is every indication that this has been written subconsciously by the Zodiac Killer and therefore he has inadvertently given us his home location of Vallejo. The word "are" immediately precedes Vallejo Times on both occasions. 

​If the Zodiac Killer lived in Vallejo when he composed these three communications, he would associate Vallejo with the present (everything that is happening in or around him). If the Zodiac Killer had traveled to San Francisco for a day out and then had returned to Vallejo, he would be referring to San Francisco in the past tense: "I have been to San Francisco and have mailed three letters." In the Vallejo Times-Herald communication text above, he is doing just that, when referring to his mailing of letters to the Chronicle and Examiner, which are approximately 40 miles away: "the other 2 parts have been mailed to the S.F. Examiner + the S.F. Chronicle."  Because now he is back home. ​

​When he is at home in Vallejo writing these communications, his mind is actually projecting forward to their future postings in San Francisco, which is where they were ultimately mailed. 
In two of the communications to the Chronicle and Examiner in San Francisco, he is referring back to his hometown Vallejo in conjunction with another mailing. Therefore he uses the plural form of the present tense, in the word "are". That is because at this moment in time (the time of writing), he is present here in Vallejo, so is effectively forced to abandon the past tense of"have". The Zodiac Killer cannot refer to Vallejo in the past tense in this instance, because the Vallejo Times-Herald office is in his locality, and therefore he is referring to it in the present of "are". 
Anything in the Zodiac Killer's locality is the 'here and now.'  Anyplace one has to travel and return, whether in the mind or reality, will be referred to in the past tense. Traveling to San Francisco physically and returning to Vallejo will now be referred to as "I have mailed", because of the distance you associate with the offices of the San Francisco Chronicle and San Francisco Examiner from Vallejo. Even if you do it in your mind.
But the Vallejo Times-Herald office is effectively on your doorstep and will therefore be seen as in the "here and now" to somebody living in Vallejo, without any real distance associated with it. Therefore it doesn't need to be referred to in the past tense, which is exactly what Zodiac does in two of his communications regarding the mailing to Vallejo- he uses the word "are". 

​The Zodiac Killer is associating the Vallejo Times-Herald as his home location, so let us use this analogy with a fictitious friend.
Zodiac is in his house opposite the Vallejo Times-Herald office and he has just finished preparing his three July 31st 1969 letters for delivery. He bids farewell to his housemate and travels to San Francisco to post his letters. Upon his return two hours later he says to his friend "I have posted two letters to the San Francisco newspapers".  Looking out of his window and pointing he states "One letter is being posted to the Vallejo Times-Herald." He would be using the present tense regarding something in the "here and now". But because he is referring to the Vallejo Times-Herald mailing in two communications he uses the present tense "are". It clearly indicates that on a subconscious level the Zodiac Killer is referring to Vallejo in the present tense, because that is where he was when he penned the three July 31st 1969 letters.

The old Vallejo Times-Herald office was at 440 Curtola Parkway, just 0.96 miles (as the crow flies) from the Springs and Tuolumne payphone.

To know that Lake Herman Road and Blue Rock Springs were frequented by courting couples, the Zodiac would have required  either first-hand knowledge of traveling that route regularly, such as commuting to work or visiting friends or family, or acquired the knowledge through a third party. Knowing this was a target rich area may have suggested that he lived locally, and free from work, cruised along Columbus Parkway and Lake Herman Road many times, before ultimately finding any suitable victims from his perspective- victims that would be in the right place at the right time.
Kim Rossmo, a pioneer of geographical profiling, stated "The San Francisco murder differs significantly from the Zodiac's other crimes. Up to this point he was hunting in locations that had a good probability of containing his desired victims. Target selection was a function of area, not of an individual. However, it is unlikely the Zodiac was successful in all his searches; serial killers typically engage in extensive hunting activities, and for every attack there are many unsuccessful search attempts. In San Francisco, however, the Zodiac controlled the situation through his selection of victim type. The need for such control could be indicative of the distance the Zodiac had to travel to the crime site. Criminals who travel longer distances to offend are less likely to use uncertain target selection techniques." 

His familiarity with the Vallejo area and its lovers' lane areas, as opposed to San Francisco, may also have inadvertently leaked from the pen of Zodiac, when only using the word "couples" in relation to the letter mailed to the Vallejo Times-Herald,  Only one confirmed person was murdered in San Francisco by the Zodiac Killer, and Paul Stine was a lone person driving his taxicab at night. We know of no couples he targeted or claimed to have targeted in this area.
​Vallejo Times-Herald: "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."
​San Francisco Examiner: "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 un till I kill a dozen people."
San Francisco Chronicle: "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 Zodiac Killer appeared to place more importance on his Vallejo Times-Herald correspondence reaching its destination quicker, by affixing four 6 cent Roosevelt stamps (24 cents postage) in total, as opposed to the San Francisco letters in which he used only two stamps on each. 
Did the Zodiac Killer employ this tactic to suggest to police he was a Vallejo resident, or was he eager to ensure he could read his offering to his hometown paper in Friday's edition, sitting in his favorite armchair. 
The cipher was mailed in three parts, with the Vallejo Times-Herald correspondence holding part one of the cipher message. Did this again show his possible home location of Vallejo, subconsciously beginning his message from where he was authoring it from.

Many have toyed with the idea of a Zodiac Killer in Riverside, California, responsible for the murder of Cheri Jo Bates on October 30th 1966 or at the very least the author of the Confession and Bates letters. There are tantalizing threads in regards to the three Bates letters allying with his 'trinity' of communications mailed to the Vallejo Times-Herald, San Francisco Chronicle and San Francisco Examiner on July 31st 1969, just over two years later. The double postage was evident, and the threat of "more victims " was apparent in both. The April 30th 1967 Bates letters stated "Bates had to die, there will be more." The Vallejo Times-Herald communication carried a similar threat: "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." 
It is also pointed out that the Zodiac Killer was responsible for the Bates letters because he signed off two of the letters with a Z-like alphabetical character. The Z representing Zodiac. The following will cast some doubt on this supposition and hopefully give us the exact date the Zodiac Killer first thought up his pseudonym Zodiac. In other words, the pseudonym Zodiac didn't exist for this individual in 1967 and therefore the alphabetical Z wasn't representative of Zodiac, or the precursor to it.​ 

On the right is an excerpt from the San Francisco Sunday Examiner and Chronicle dated August 3rd 1969. The Vallejo Police Chief Jack E Stiltz "urged the writer yesterday to send more letters with more facts to prove his connections with the crimes." The Bay Area murderer duly obliged with the 'Debut of Zodiac' letter, received by the San Francisco Examiner on August 4th 1969. It was called the "Debut" letter for good reason- it was the day the Bay Area murderer revealed his pseudonym to the world, opening with the now infamous line "This is the Zodiac speaking." But if Chief Jack E Stiltz had not requested more details, it is extremely unlikely this correspondence would have been mailed at all. We would have had to wait over two months until the October 13th 1969 Paul Stine letter for Zodiac to introduce his pseudonym into the public domain, if ever at all. 
The 'Debut of Zodiac' letter only existed because of Chief Jack E Stiltz- and this communication is the only reason our knowledge of the killer as Zodiac existed at this point in time. The choice of the pseudonym being revealed in this letter was not a choice made by the killer, because he wouldn't have written it, if not pressed into action by reading this newspaper column. 
In fact, the Zodiac Killer may never have existed under this name, if it wasn't for this publication by the San Francisco Sunday Examiner and Chronicle on August 3rd 1969. There is further evidence that the American public played a key role in igniting the killer's choice of pseudonym 
If the Z on the Bates letters really stood for Zodiac, then the murderer of Cheri Jo Bates, David Faraday, Betty Lou Jensen and Darlene Ferrin had almost three years to create an appropriate pseudonym before the July 31st 1969 'trinity' of communications proclaiming his collection of slaves for the afterlife. He had six and a half months from the December 20th 1968 double murder until the attack at Blue Rock Springs Park. He had 27 days from the July 4th 1969 attack until the mailing of the July 31st 1969 'trinity.'  This was his arrival to the world, yet he didn't sign off any of these letters with 'Zodiac' or even a 'Z'.
If he was surreptitiously operating under the name of Zodiac at this point, he clearly didn't give this impression when he opened up two of his communications with the rather unoriginal opening line of "I am the killer of the 2 teen-agers last Christmass at Lake Herman and the Girl last 4th of July" to the Vallejo Times-Herald and San Francisco Examiner. The San Francisco Chronicle was equally devoid of any pseudonym or initial, beginning with "This is the murderer of the 2 teenagers last Christmass at Lake Herman + the girl on the 4th of July near the golf course in Vallejo." 
The reason behind this, being that he hadn't formulated the pseudonym Zodiac at this juncture. The prompt was to come just three days later on Sunday August 3rd 1969- the day the 'Zodiac Killer' was born in the mind of the killer. 
The San Francisco Sunday Examiner and Chronicle opened with the lines "A self-accused killer failed to keep a threat of mass murder here, but there was no slackening of tension or mystery caused by the warning. The police department telephone system was clogged at times by anxious callers asking if the "cipher killer" had been caught."
The killer read this publication and was probably dismayed at the pseudonym of "cipher killer" attributed to him. He sat back in his armchair and was likely sparked into action to create his own pseudonym. He thumbed through the San Francisco Sunday Examiner and Chronicle of August 3rd 1969 during the day, until he arrived at the Zodiac horoscope page, and a light went on. This was the day the 'Zodiac Killer' was born.    

The following will be explaining in more detail the subconscious wording of the Zodiac Killer in his first three communications with the Bay Area newspapers, putting forward a compelling argument that the confirmed murderer of five was a resident of the Vallejo area. The Zodiac Killer would never willingly have given us his name or the locality of his residence, however, one could argue that had he revealed his home location without realizing it, then it is likely true. To do this, we have to examine closely the wording he chose on his July 31st 1969 letters using the present and past tense. Here is what the Zodiac stated on each communication:
Vallejo Times-Herald: "Here is a cyipher or that is part of one. the other 2 parts have been mailed to the S.F. Examiner + the S.F. Chronicle."
San Francisco Examiner: "Here is a cipher or that is part of one. The other 2 parts are being mailed to the Vallejo Times + S.F. Chronicle." 
San Francisco Chronicle: "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." 

You will notice the two San Francisco newspapers are being addressed in the present tense regarding the other two mailings, using the word ARE. While the Vallejo Times-Herald newspaper is being addressed in the past tense regarding the other two mailings, using the word HAVE. There is every indication that this has been written subconsciously by the Zodiac Killer and therefore he has inadvertently given us his home location of Vallejo. The word "are" immediately precedes Vallejo Times on both occasions. 

If the Zodiac Killer lived in Vallejo when he composed these three communications, he would associate Vallejo with the present (everything that is happening in or around him). If the Zodiac Killer had traveled to San Francisco for a day out and then had returned to Vallejo, he would be referring to San Francisco in the past tense: "I have been to San Francisco and have mailed three letters." In the Vallejo Times-Herald communication text above, he is doing just that, when referring to his mailing of letters to the Chronicle and Examiner, which are approximately 40 miles away: "the other 2 parts have been mailed to the S.F. Examiner + the S.F. Chronicle."  Because now he is back home. ​  

When he is at home in Vallejo writing these communications, his mind is actually projecting forward to their future postings in San Francisco, which is where they were ultimately mailed. 
In two of the communications to the Chronicle and Examiner in San Francisco, he is referring back to his hometown Vallejo in conjunction with another mailing. Therefore he uses the plural form of the present tense, in the word "are". That is because at this moment in time (the time of writing), he is present here in Vallejo, so is effectively forced to abandon the past tense of "have". The Zodiac Killer cannot refer to Vallejo in the past tense in this instance, because the Vallejo Times-Herald office is in his locality, and therefore he is referring to it in the present of "are". 
Anything in the Zodiac Killer's locality is the 'here and now.'  Anyplace one has to travel and return, whether in the mind or reality, will be referred to in the past tense. Traveling to San Francisco physically and returning to Vallejo will now be referred to as "I have mailed", because of the distance you associate with the offices of the San Francisco Chronicle and San Francisco Examiner from Vallejo. Even if you do it in your mind.
But the Vallejo Times-Herald office is effectively on your doorstep and will therefore be seen as in the "here and now" to somebody living in Vallejo, without any real distance associated with it. Therefore it doesn't need to be referred to in the past tense, which is exactly what Zodiac does in two of his communications regarding the mailing to Vallejo- he uses the word "are". 

The Zodiac Killer is associating the Vallejo Times-Herald as his home location, so let us use this analogy with a fictitious friend.
Zodiac is in his house opposite the Vallejo Times-Herald office and he has just finished preparing his three July 31st 1969 letters for delivery. He bids farewell to his housemate and travels to San Francisco to post his letters. Upon his return two hours later he says to his friend "I have posted two letters to the San Francisco newspapers".  Looking out of his window and pointing he states "One letter is being posted to the Vallejo Times-Herald." He would be using the present tense regarding something in the "here and now". But because he is referring to the Vallejo Times-Herald mailing in two communications he uses the present tense "are". It clearly indicates that on a subconscious level the Zodiac Killer is referring to Vallejo in the present tense, because that is where he was when he penned the three July 31st 1969 letters.

The old Vallejo Times-Herald office was at 440 Curtola Parkway, just 0.96 miles (as the crow flies) from the Springs and Tuolumne payphone.

The following will provide an alternative to an earlier article 'The Lake Berryessa Greeting Card,' regarding the inspiration of the 340 character cipher and the two week period it was designed by the Zodiac Killer. 
On October 22nd 1969 Will Stevens wrote an article for the San Francisco Examiner entitled 'Cipher Expert Dares Zodiac to Tell Name.' Dr D.C.B. Marsh, president of the American Cryptogram Association challenged Zodiac to reveal his name by creating a cipher for them to crack. He 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."
​Michael Cole authored an excellent article detailing how Zodiac would take up this challenge exactly six months later, when he mailed the '13 Symbol' cipher to the newspapers, beginning with the line "This is the Zodiac speaking. By the way have you cracked the last cipher I sent you. My name is...."
However, we will slightly deviate from the Michael Cole article by suggesting that both the 340 character cipher and '13 Symbol' cipher were responses initiated by the challenge of Dr D.C.B. Marsh. He issued the challenge- however complicated- and Zodiac would certainly oblige with his most complex cipher of all, just 17 days later. The Zodiac Killer, knowing he was dealing with cryptogram experts such as  Dr D.C.B. Marsh, professor of mathematics at the Colorado School of Mines in Golden, would certainly not disappoint, mailing the 340 character cipher just over two weeks later. He would then follow up on April 20th 1970 with a smaller code, implying he was now prepared to reveal his name.  

In his first correspondence to the newspapers the Zodiac Killer promised that the 408 cipher would contain his name, by stating "In this cipher is my idenity." This notion would soon be quashed, when the three-part cipher was cracked by Donald Gene and Bettye June Harden of Salinas, California, in a matter of days.
But this challenge on October 22nd 1969 was laid down by cryptogram experts, and probably the reason the Zodiac Killer went to the extreme, creating a cipher that remains unbroken nearly half a century later. Dr D.C.B. Marsh​ stated "The killer wouldn't dare, as he claimed in letters to the newspapers, to reveal his name in a cipher." But the Zodiac wasn't going to play ball that easily, yet he did likely answer this challenge directly on the final line of the 340 character cipher by revealing his name in part. He placed the 'near Zodiac' from character 333 to 338. 
In the 408 cipher, the final section of the decoded message read "I will not give you my name because you will try to slow down or stop my collecting of slaves for my afterlife." The '13 Symbol' cipher opened with the line "This is the Zodiac speaking. By the way have you cracked the last cipher I sent you. My name is...."
Therefore, this should give us a clue to how the Zodiac Killer constructed the final two lines of the 340 character cipher, bearing in mind it was a response to the challenge proffered by Dr D.C.B. Marsh, and in part, revealed his pseudonym Zodiac. 
Here is one example of how the Zodiac may have signed off the 340 cipher, when you consider there are only two symbols after the 'near Zodiac,' in positions 339 and 340. There cannot be many reasonable options to consider for a two letter word.  

There are of course alternatives, such as "I will soon tell you who the Zodiac is," "My next cipher will reveal who the Zodiac is" or "The day will come when you'll know who Zodiac is." There are a myriad of possibilities, but always with the final two words being "Zodiac is." 
If the Zodiac began the 340 character cipher top down, are we to believe the 'near Zodiac' fell out by chance, and was not created specifically as a response to the American Cryptogram Association to reveal his name. The cipher may have signed off with something similar to the wording above, but could have been created from the bottom up, so as to lead us into his next cipher on April 20th 1970. The 408 cipher stated "I will not give you my name because you will try to slow down or stop my collecting of slaves for my afterlife." The Zodiac Killer was then laid down a challenge on October 22nd 1969, and we know his propensity to reply to individuals when challenged. Seventeen days later, a cipher arrived at the San Francisco Chronicle. Can this be a coincidence such a short time after the challenge by Dr D.C.B. Marsh? He signs off the 340 character cipher, now promising he will soon reveal who the Zodiac is. Then 5 months later he seemingly is true to his promise, stating "This is the Zodiac speaking. By the way have you cracked the last cipher I sent you. My name is...."
The second and third ciphers may be linked by the name Zodiac and a simple trick of mathematics, shown here. 
​           

Did the fact that Dr D.C.B. Marsh, being a professor of mathematics, play any part in this possible numerical solution, or the Zodiac Killer's  circled three eights (if indeed that is what they were). The killer would later state in the April 20th 1970 letter "PS I hope you have fun trying to figgure out who I killed."​​​   
Dr Marsh told the Examiner "That first code was complicated... and the maker obviously knew what he was doing. But it never included the true identity of Zodiac." But can we be sure the Zodiac read this article and responded from his basement residence.
Look at the accompanying news article to the Dr D.C.B. Marsh article, entitled  "Tunisia Hit by Heavy Rains." It reads "New torrential rains pounded Tunisia all last night and today, nearly isolating Tunis and Bezerte from the rest of the country. Broadcasts warned residents of low-lying suburbs to head for higher ground. Basements filled, and some ancient buildings in the Medina showed signs of crumbling."
The Zodiac Killer replied in the April 20th 1970 offering, by stating
"I have killed ten people to date. It would have been a lot more except that my bus bomb was a dud.  I was swamped out by the rain we had a while back." This however, is most likely too cryptic even for Zodiac. 
But the fact remains, that Dr D.C.B. Marsh set the Zodiac Killer a challenge, and a little over two weeks later he responded with an even more "complicated" cipher than the 408, possibly promising the professor of mathematics a solution to his identity in due course. One that arrived on April 20th 1970- but whether it held true to the promise of his name is another matter.​ 

Michael Cole- http://zodiacrevisited.com/name-cipher-motivation