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

Professor D.C.B. Marsh, in the October 22nd 1969 San Francisco Examiner newspaper article by Will Stevens, laid down a challenge to the Zodiac Killer to reveal his name. The newspaper stated "Dr Marsh told the Examiner today: "The killer wouldn't dare, as he claimed in letters to the newspapers, to reveal his name in the cipher to established cryptogram experts. He knows, to quote Edgar Allen Poe, that any cipher created by man can be solved by man. Zodiac has not told the truth in his cipher messages to the Examiner, the Chronicle and the Vallejo Times-Herald. Zodiac has not done this, because to tell the complete truth in relation to his name -in cipher code - would lead to his capture. I invite Zodiac to send The American Cryptogram Association a cipher code - however complicated - which will truly and honestly include his name". It was speculated that the Zodiac Killer certainly wasn't going to provide another conventional cryptogram to be easily decoded, so instead created the appearance of a cryptogram with hidden "puzzles" contained within it, such as "paradice" and "slaves" running vertically and horizontally across its mid-section. This was later revealed in the 'Halloween' card, where the Zodiac Killer belatedly informed us the 340 code was "sorry no cipher" and placed "paradice" and "slaves" in a cross formation to point us in the right direction.   

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

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

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

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

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

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

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

Using old and new material, we will take a comprehensive look at the 'Dripping Pen' card mailed by the Zodiac Killer on November 8th 1969, and attempt to link it to a future threat of murder. The card itself was most likely chosen for purpose, referencing the immediate aftermath of the attack on Bryan Hartnell and Cecelia Shepard at Lake Berryessa on September 27th 1969. Approximately five minutes after the brutal stabbing, the killer walked to the side of Bryan Hartnell's white Volkswagen Karmann Ghia and wrote "Vallejo 12-20-68, 7-4-69, Sept 27-69 -6:30 by knife". The hand the killer wrote on the car door with, was likely the hand he used during the attack on the young couple, almost certainly peppering his dominant hand with blood, and consequently to the marker pen he wrote with. So, the choice of greeting card stating "Sorry I haven't written, but I just washed my pen" was likely a sardonic reference to the callous and bloody attack at Lake Berryessa. The addition of "Aug" on the card inner, a suggestion of his involvement in the double murder of Deborah Furlong and Kathy Snoozy in San Jose on August 3rd 1969. This, coupled with the footnote of "by knife" written on the car door, was likely deliberately engineered to steer investigators toward this conclusion. They had after all considered this premise in the October 1st 1969 edition of the San Francisco Examiner, in which was stated "And today San Jose police, to the south, inquired of law enforcement officers here whether there was indication that the "Cipher Killer" might be linked to the knife slaying of two teenage girls Aug.3, still unsolved". This wouldn't be forgotten by the Zodiac Killer.   

Another reason to believe the 'Dripping Pen' card was referring to Lake Berryessa can be found in its design. The Zodiac Killer, almost without exception, would give us a running total of his victims, occasionally writing the victim count on the horizontal wing of the crosshairs. The only two times this was not the case, was the November 8th 1969 'Dripping Pen' card and the car door of Bryan Hartnell's white Volkswagen Karmann Ghia. In both of these writings he gave us his Zodiac crosshairs with the months of his murders underneath. This was the first and last time he would ever do this.

If you run the message from the face of the 'Dripping Pen' card to inner, it reads "Sorry I haven't written, but I just washed my pen and I can't do a thing with it". So, when the Zodiac Killer wrote "I get aufully lonely when I am ignored, so lonely I could do my Thing", he was indicating that in the future when he needed some attention, he would write again. His Thing being his propensity to put pen to paper, or in the case of Lake Berryessa, to metal. He was effectively addressing the police when he wrote "I though you would need a good laugh before you hear the bad news. You won't get the news for a while yet". In fact, the bad news would arrive in exactly thirteen days time - and it was directed towards the police in regards to the month of August. In effect, his next correspondence would be pushing the same narrative as the car door and greetings card, of his involvement in the deaths of Deborah Furlong and Kathy Snoozy. 

​On November 21st 1969, a letter arrived at the San Jose Police Department, addressed to a particular law enforcement officer. The letter was threatening a widow - so much so - that police initiated 24-hour surveillance on the woman's home. The police stated that "they believed the widow in the message may be Mrs......" In other words, the woman wasn't directly named in the correspondence, but they had by reasonable deduction, concluded who the threat was aimed at. I believe that the Zodiac Killer, in his continued drive to cement the notion of his involvement in the two teenage girls murders, mailed this "bad news" to the San Jose Police Department. Can it really be a coincidence that he wrote "by knife" on the car door to plant the seed, added the "Aug" on the 'Dripping Pen' card, then mailed his next correspondence to the City of San Jose? In addition, this new communication began with some familiar words: "There's no doubt I will do my Thing".  

On November 21st 1969, the San Jose Police Department would still have been devoting many hours to the unsolved murders of these two teenage girls, and likely receiving many tips from potential eyewitnesses and the residents of San Jose, eager to assist in the investigation. What better way for the Zodiac Killer to convince law enforcement of his potential involvement in this crime, by threatening to do his Thing on one of these residents.

I have no doubt the Zodiac Killer was scouring the newspapers about this crime - so imagine he came across such a headline:
"An elderly widow, Maureen Jones, was today helping police with their investigation into the senseless murders of two young girls in San Jose, Sergeant Johnston said", or "An elderly widow, residing at Seacreek Way, was today helping police with their investigation into the senseless murders of two young girls in San Jose, Sergeant Johnston said". These article excerpts are fictitious, designed to show what Zodiac  may have read in any number of articles I have no access to. 

The Zodiac Killer never mentioned his victims by name, so it is entirely plausible that whether he knew this woman's name or not, he could, by sending a threatening letter to police using the term "widow", and addressing the communication to "Sergeant Johnston", convince police that the threat was a credible one. This may be why the police believed they knew who the woman was, despite the fact her name was never mentioned in the correspondence mailed to the San Jose Police Department. Because she had recently received newspaper coverage.     

A small code arrived with the November 21st 1969 communication. The short code (shown above in the FBI files) was
​-- + 6 2 + --, containing two dashes either side, two pluses, and the numbers 6 and 2. The idea that anybody looking at this code could arrive at 1620, without having previous reason to suspect this four number solution, seems unlikely. But if investigators knew that "Maureen Jones" lived at a residence, such as 1620 Seacreek Way, San Jose, then they might have reason to believe this is what the code was implying. Earlier newspaper reports stated "A killer armed with a thin-bladed stiletto was hunted here today as the one who savagely stabbed to death two teenage girls yesterday as they picknicked in Almaden Valley. The scene where the bodies were found is just south of Blossom Hill Road, two blocks west of Calahan in the northern end of the valley. About 10:00 am yesterday, the girls packed a lunch and left Deborah's parents' San Jose home for a picnic atop a grassy knoll nearby. The picnic ground is a rugged area, near a narrow, serpentine trail used by motorcyclists for hill-climbing contests".  So, if we could find a 1620 residence in San Jose, possibly close to the crime scene, this may be the location of the "widow" Zodiac was targeting.

As shown above, in the October 1st 1969 San Francisco Examiner article, "San Jose police, to the south, inquired of law enforcement officers here whether there was indication that the "Cipher Killer" might be linked to the knife slaying of two teenage girls Aug.3".  Therefore, would it really be that surprising if the Zodiac Killer had capitalized on their suspicions and mailed a threat to the San Jose Police Department? He knew he would be taken seriously by police - and why they were prepared to instigate 24-hour surveillance on the residence of the "widow" mentioned in the letter.

In the last article 'More Than Just By Knife' we looked at the message "by knife" on the car door at Lake Berryessa and the month of "Aug" on the 'Dripping Pen' card, mailed on November 8th 1969. It was argued that the reference to "by knife" meant so much more to the killer than just telling us the patently obvious, that Bryan Hartnell and Cecelia Shepard were attacked with a knife. It was a declaration of what was soon to be revealed on November 8th 1969, that the Zodiac Killer was suggesting his involvement in the Kathy Snoozy and Deborah Furlong double stabbing on August 3rd 1969.  

The addition of the time on the car door also appeared to be lacking any great purpose, so this led me to believe that the time of 6:30, just like "by knife", also had some significance to the killer. The Zodiac Killer would certainly have been scouring the newspapers around the time of his July 31st 1969 and August 4th 1969 communications to the San Francisco Chronicle, San Francisco Examiner and Vallejo Times-Herald. It is apparent that his narcissistic tendencies would have compelled him to purchase the newspapers for any reading material about himself. 

It must therefore have annoyed him greatly that the Kathy Snoozy and Deborah Furlong murders featured on the front pages of the San Francisco Examiner on August 4th 1969 and the San Francisco Chronicle on August 6th 1969, when he had declared at the same time that he "was not happy to see that he did not get front page coverage" in the 'Debut of Zodiac' letter. This is probably the moment he decided on an altogether more hands-on approach to his method of murder - by knife. The inspiration for the Lake Berryessa attack may have come straight from the pages of the San Francisco Examiner. On the same day the Zodiac Killer hand delivered his 'Debut of Zodiac' letter to the Examiner offices, the San Francisco Examiner headlined with '2 Girls Stabbed-Picnic Murders Footprint Clue'. Apart from "Girls", this headline could easily have been written for the September 27th 1969 Lake Berryessa attack.       

Bryan Hartnell and Cecelia Shepard were enjoying a pleasant afternoon/early evening picnic near the Oak Shores Recreation Area, when a man in an executioner's outfit changed everything. The San Francisco Examiner (above) stated "San Jose-A killer armed with a thin-bladed stiletto was hunted here today as the one who savagely stabbed to death two teenage girls yesterday as they picknicked in Almaden Valley. The scene where the bodies were found is just south of Blossom Hill Road, two blocks west of Calahan in the northern end of the valley. About 10:00 am yesterday, the girls packed a lunch and left Deborah's parents' San Jose home for a picnic atop a grassy knoll nearby. The picnic ground is a rugged area, near a narrow, serpentine trail used by motorcyclists for hill-climbing contests". 

​The question being: did the Zodiac Killer switch from gun to knife, head down the serpentine trail of Lake Berryessa to target unsuspecting picknickers or people enjoying a relaxing day out, because he just fancied a change, or did he believe this was his path to guaranteed "front page coverage", just like the brutal stabbing of the two young girls in San Jose? The car door may have held the answer, by the addition of the "by knife" phrase. The Zodiac Killer was effectively saying "do I get front page coverage now". But how does the time of 6:30 (pm) on Bryan Hartnell's car door play into the Kathy Snoozy and Deborah Furlong murders of August 3rd 1969.

Serial killer Karl Francis Werner may inadvertently have been responsible for the murder of Cecelia Shepard and attempted murder of Bryan Hartnell at Lake Berryessa on September 27th 1969. Many people have made the case for questioning the Lake Berryessa attack as a Zodiac crime, by pointing out that the Zodiac Killer included the month "Aug" on his November 8th 1969 'Dripping Pen' card, yet he failed to include this date on the car door of Bryan Hartnell's white Karmann Ghia. However, the inclusion of August on the 'Dripping Pen' card may be the confirmation of the "by knife" message on the car door withheld by police. As early as October 1st 1969, only four days after the Lake Berryessa attack, an article in the San Francisco Examiner entitled 'Sex Fiend Sought For Six Killings' stated "A psychotic killer police say brutally slays females for sexual gratification is loose in the North Bay today". Extremely irresponsible and factually incorrect journalism, that may have driven the attack on a lone male in San Francisco to prove this assertion incorrect.

The Zodiac Killer would use this "North Bay" reference only twelve days later, after the callous execution of taxicab driver Paul Stine on October 11th 1969 in San Francisco, to confirm his link to Berryessa. The Zodiac Killer mailed a letter to the San Francisco Chronicle with the admission "I am the same man who did in the people in the north bay area". The San Francisco Examiner would detail the withholding of part of the message on the car door at Berryessa, stating "There was more to the inked car door message than dates. But Captain Townsend masked the information, considered it "classified". In the September 30th 1969 edition of the Examiner, entitled 'Police Dare Cipher Killer', Captain Don Townsend dared him to write or phone again to prove he wrote the message: "There is more, and we are not releasing it now. Why? Because this man has a pattern of contacting the police and newspapers by phone and letter after his killings. We are holding back part of the note because, when and if he writes, he can say what else was written there - and thus prove he is the 'man who loves to kill'"   

I believe the Zodiac Killer did respond - not as the police had hoped - but indirectly, by the inclusion of the month of "August" on the November 8th 1969 'Dripping Pen' card, just five weeks later. The killer wrote "Des, July, Aug, Sept, Oct = 7". The murders in December, July and October were all perpetrated with a firearm, and police knew that September represented the Lake Berryessa attack with a knife. Therefore, it left "Aug" to figure out.

​The answer lies in the October 1st 1969 San Francisco Examiner edition, where investigators contemplated a link to the brutal stabbing and murder of two young girls in San Jose on August 3rd 1969. Deborah Gaye Furlong (14) and Kathie Ann Snoozy (15) were found murdered in the Bay Area of San Jose, in what can only be described as a barrage of knife wounds. These murders were eventually linked to the hand of Karl F. Werner, who was also convicted of the Kathy Bilek murder. However, these murders were not solved until 1971. The October 1st 1969 Examiner stated "And today San Jose police, to the south, inquired of law enforcement officers here whether there was indication that the "Cipher Killer" might be linked to the knife slaying of two teenage girls Aug.3, still unsolved".   

This is exactly what the Zodiac Killer had hoped - and why he perpetrated the Lake Berryessa attack in the first place. He was laying the seeds for law enforcement to conclude this very idea - and the reason he switched to a knife attack on this occasion. The "Aug" reference was pushing law enforcement to conclude he was responsible for the brutal slaying of Kathy Snoozy and Deborah Furlong - "by knife" - and therefore, in his mind, unequivocally linking himself to the Lake Berryessa stabbings. Had Karl Francis Werner not killed Kathy Snoozy and Deborah Furlong, it is my contention that Cecelia Shepard would still be alive today.

The Zodiac Killer knew that he had to kill to secure the attention of the newspapers, and the bolder the attack, the more publicity he would generate. He had murdered three young people by July 4th 1969 and had sent newspapers a trinity of communications on July 31st 1969 containing three parts of a cipher, determined to secure the headlines he felt he deserved. His letters promised more murder 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". To his dismay, he felt he was being short-changed, writing in the August 4th 1969 'Debut of Zodiac' letter "I was not happy to see that I did not get front page coverage". At this point in time, without doubt, the Zodiac Killer would have been scouring the newspapers for progress on solving his cipher, along with updates on his crimes. Then came the savage knife attack on Kathy Snoozy and Deborah Furlong in San Jose, featured on the front page of the San Francisco Chronicle on August 6th 1969: ​   

The Zodiac Killer likely read this article and knew the course of action he needed to take to secure "front page coverage". His next crime had to be bolder, more savage and more personal - using a knife. The brutal murder of these two young girls by Karl Francis Werner would ultimately change the tactics of the Zodiac Killer in his relentless pursuit of notoriety. Seven weeks later he arrived on the shores of Lake Berryessa.

It has been questioned as to why the Zodiac Killer wrote "by knife" on the car door of Bryan Hartnell's vehicle, when it was patently obvious the couple had been stabbed with a knife. But it was much more than this. The writing of "by knife" on the car door was a statement to the publicity he felt he deserved - and was also partly alluding to the Snoozy and Furlong murders he would lay claim to just six weeks later. The "Aug" reference on the November 8th 1969 'Dripping Pen' card was further corroboration to the 'hidden' message on the car door of Bryan Hartnell. The Zodiac Killer attacked Bryan Hartnell and Cecelia Shepard with a knife at Lake Berryessa, then planted the seed on the car door to hint towards the San Jose murders just seven weeks earlier, to which he would finally confirm on his 'Dripping Pen' card at the beginning of November. He knew the month of August would be interpreted by law enforcement as the murder of Snoozy and Furlong, because law enforcement had contemplated the link only weeks earlier. The "by knife" message on the car door at Lake Berryessa, would on November 8th 1969, now hold much more significance than it did on September 27th 1969. 

Confirmation of the Snoozy and Furlong "August" link, would arrive on July 13th 1971, when a pasted card was mailed to the San Francisco Chronicle with the words "Near Monticello Shought Victims 21 ...... In The Woods Dies April". The Zodiac Killer was now claiming (or at the very least associating himself with) Karl Francis Werner's third victim, Kathy Bilek. On Sunday, April 11th 1971, Kathy Bilek (18) visited Villa Montalvo in Saratoga, with the intent to read and engage in a spot of birdwatching in the seclusion of a remote, wooded portion of the park, near a small stream. Her body was found the next day by her father, Charles, while Santa Clara County Sheriff's deputies searched nearby. She had been stabbed 17 times in the back and 32 times in her chest and stomach. The Zodiac Killer's requirement to associate himself with three brutal stabbings, despite the fact he wasn't responsible for any, tells you all you need to know regarding his quest for notoriety - and why he was only too willing to write "by knife" on the car door at Lake Berryessa.on September 27th 1969. Its meaning went far beyond the obvious.      

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

Here I would like to return to an old topic with a fresh approach, partly inspired by 'Nobody,' a regular contributor to this site.
As early as August 10th 1969 Professor D.C.B. Marsh of the American Cryptogram Association (ACA) was commenting on the Zodiac ciphers. In the San Francisco Sunday Examiner & Chronicle he praised Donald Harden's deciphering skills and called the code "complicated and obviously drawn by somebody who knows his business". 
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The Zodiac Killer had already responded to prompts by Vallejo Police Chief Jack Stiltz to send more details to prove the letter writer and killer were one and the same. The more the Zodiac Killer wrote, not only lessened his time for killing, but may have provided additional clues to detectives regarding his identity. This tactic was likely adopted by Professor D.C.B. Marsh in the October 22nd 1969 San Francisco Examiner newspaper article by Will Stevens, which laid down a challenge to the Zodiac Killer to reveal his name. The newspaper stated "Dr Marsh told the Examiner today: "The killer wouldn't dare, as he claimed in letters to the newspapers, to reveal his name in the cipher to established cryptogram experts. He knows, to quote Edgar Allen Poe, that any cipher created by man can be solved by man. Zodiac has not told the truth in his cipher messages to the Examiner, the Chronicle and the Vallejo Times-Herald. Zodiac has not done this, because to tell the complete truth in relation to his name -in cipher code - would lead to his capture. I invite Zodiac to send The American Cryptogram Association a cipher code - however complicated - which will truly and honestly include his name." 

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

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

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

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

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

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

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

The Dr. Marsh newspaper article opened with "A Challenge perhaps unique in the annals of American crime was injected today into the bizarre case of the killer who begins his letters to newspapers 'This is the Zodiac Speaking'."
The article continued, and bemoaned the fact that Zodiac hadn't revealed his true identity: "Zodiac has not done this, because to tell the complete truth in relation to his name - in cipher code - would lead to his capture. I invite Zodiac to send The American Cryptogram Association a cipher code - however complicated - which will truly and honestly include his name." 

'A Few Words on Secret Writing' stated "This challenge has elicited but a single response, which is embraced in the following letter. The only quarrel we have with the epistle, is that its writer has declined giving us his name in full. We beg that he will take an early opportunity of doing this, and thus relieve us of the chance of that suspicion which was attached to the cryptography of the weekly journal above-mentioned–the suspicion of inditing ciphers to ourselves. The postmark of the letter is Stonington, Conn." ​link. 

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

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

In a recent article David Oranchak posed the question "Are the Ciphers Gibberish", analyzing the pros and cons to the legitimacy of the Zodiac 340 cipher. There is, however, another legitimate argument to be discussed when searching for a solution to the Zodiac Killer's second cipher. Is it worth trying to solve at all? If it does contain a message, it will likely be a collection of inane ramblings akin to the solved 408 cipher. There will of course be the immense notoriety attached to your name, having been the cryptographer who broke the infamous Zodiac code, from which numerous television appearances and a book deal will inevitably follow. In the midst of tragedy, your name will be up in lights. But here is the reality check. Even if you do achieve the seemingly insurmountable task of unequivocally solving the 340 cipher, then comes the next insurmountable hurdle - convincing people you have the correct solution. In a Zodiac community wearily grazing on skepticism and fueled by a heavy dose of déjà vu syndrome, your perfectly good solution will likely drift on down the river with barely a ripple from the esteemed adjudicators.   

Even if it does get snagged by an overhanging branch for a fleeting moment, attempting to prove that the "key" used to decipher it, is the one Zodiac intended, will again create a hill you can never climb.

There are so many claimed solutions to the 340 cipher haystack, that if one really existed, it will eventually be as hard to find as a solution to the cipher itself. David Oranchak stated here:   
​"The 340 cipher has 63 unique symbols. If one of 26 plaintext letters can be assigned to each symbol, then the number of possible solutions is 26 raised to the 63rd power. So, how many of those solutions would computers need to examine PER SECOND to finish within 100 years? The answer is about 4.4 x 10^80 solutions, or 440 million billion billion billion billion billion billion billion billion. This is LIGHT YEARS beyond what current computers are capable of.
According to Top500.org, the world's fastest supercomputer as of November, 2011, achieved a computational power of 10.51 Petaflop/s, or 10.51 quadrillion floating point operations per second. If you were somehow able to check a decryption solution of the 340 cipher using a single floating point operation, then this supercomputer could go through all of the possible solutions to the 340 cipher in about 1.3×10^57 years. By comparison, our humble universe is estimated to be only 13.7 x 10^9 years old!"

With so many variables that can be applied to the cipher, or more importantly, the one conjured up by the warped and dissociative brain of Zodiac, the probability is, that a supercomputer designed by logic and born from reality will probably be heading course on the wrong superhighway. Throw in a handful of Zodiac errors into the mix, could mean proving your solution an impossible task to the baying hordes of furrowed experts, armed with statistical probabilities. Solving the 340 cipher may yet prove to be the easy part, however, convincing somebody else you have, could take a quadrillion years you haven't got.

David Oranchak stated "When Z408 was cracked, the papers talked about how the solvers took advantage of patterns found in the cipher text. Zodiac could have focused on somehow removing those patterns from Z340. Or maybe he found some obscure idea in a book or one of those pulp fiction detective stories".
​Herein lies part of the problem. If you discover an obscure idea that answers key elements of the 340 cipher, or provides a readable message (possibly using a rotating key code), then it could be argued that your obscure idea is so obscure, that it isn't worth considering as a credible solution and thereby roundly dismissed as lunacy. The more crazy the solution, the more unlikely it is, despite being crafted by the perfectly sane Zodiac.

Alternatively, how do you prove the cipher gibberish while it still remains unsolved in the eyes of most observers. By extension, if it's unsolved, then it still has a possible solution. But be warned - if you do find the real solution to the 340 cipher, you will have to work far harder than the Harden's did in 1969 to convince the world you are correct. And my guess is, you never will.    

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

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

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

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

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

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

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

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

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.  

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

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

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

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

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

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

There are many ways to interpret the 'Dripping Pen' card mailed by the Zodiac Killer on November 8th 1969 and here is another.
​Some people use the 'evidence of absence' argument to suggest the Lake Berryessa attacker was not the Zodiac Killer- articulating that his lack of mailed correspondence after the double stabbing was evidence for his absence from the crime scene.
​His communication on the car door just six minutes after the attack- probably to him- seemed like unassailable proof he was placing himself at the crime scene, just like attaching Paul Stine's shirt piece to his October 13th 1969 letter.
​At Lake Berryessa he took his handwriting to the crime scene, while at Presidio Heights he took the crime scene to his handwriting. A reverse signature one might say. However, not many people question Zodiac's involvement in the murder of taxicab driver Paul Stine. The idea that the Zodiac Killer never communicated his involvement in the Lake Berryessa crime is patently false, despite our need for a more comprehensive attribution to the events of September 27th 1969. Yet, his correspondences on October 13th 1969 and November 8th 1969 may very well have both referenced the Lake Berryessa attack, but in different ways.
The author of the October 13th 1969 Paul Stine letter opened with the words "This is the Zodiac speaking. I am the murderer of the taxi driver over by Washington St + Maple St last night, to prove this here is a blood stained piece of his shirt. I am the same man who did in the people in the north bay area."
The Zodiac Killer on the car door of Bryan Hartnell's white Karmann Ghia clearly attributes both of his first two attacks under the banner of Vallejo, despite the fact David Faraday and Betty Lou Jensen were murdered in Benicia. In fact, the Zodiac Killer never referenced Benicia in any of his communications, while he mentioned Vallejo several times. If the Zodiac Killer played no part in the Lake Berryessa attack, then his above introduction could have read "This is the Zodiac speaking. I am the murderer of the taxi driver over by Washington St + Maple St last night, to prove this here is a blood stained piece of his shirt. I am the same man who did in the people in the Vallejo area." However, he chose to use the "north bay area" for the first time, which incorporates the Napa and Sanoma wine regions. ​

Despite the claims that an impostor could have faked the Lake Berryessa phone call to mimic Zodiac's rhetoric of the Blue Rock Springs call, by reading the transcripts widely publicized in the newspapers, it appears the copycat would then fail to read the newspapers of the Benicia attack, and bundled both attacks under the banner of Vallejo on the car door, in complete harmony with a Zodiac Killer who always failed to document the simplest of facts- that his first crime was perpetrated in Benicia. The implication being- that they are one and the same person.
The divergence from Vallejo in the October 13th 1969 Stine letter confession, therefore, proof of his admission to the Lake Berryessa attack. The Zodiac Killer would then further indicate his involvement by the lake, in the cryptic November 8th 1969 'Dripping Pen' card communication, not only by the addition of "Sept"  in his running victim count, but through the cover image and wording within it.  
The style of the card may have been purposely chosen in reference to the Lake Berryessa attack and mailed in unison with the 'Bus Bomb' letter, which  elaborated upon his recent murder.
On October 18th 1969, Attorney General Thomas C Lynch implored Zodiac to turn himself in, stating "We will see that he gets help and all his rights are protected. He is obviously an intelligent individual. He knows that eventually he will be taken into custody, so it would be best that he give himself up, before tragedy is written in blood." 
Three weeks later the Zodiac Killer mailed a greeting card, depicting a fountain pen having been washed by its owner. The card itself read "Sorry I haven't written, but I just washed my pen...and I can't do a thing with it." Zodiac then added the words "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."

It is clear the Zodiac has simply parroted the word "thing" from the wording on the card, and began to write the letter 'T' in lower case. It is equally probable the Zodiac wrote the entire word "thing" in normal writing, before emphasizing it in bold fashion, to highlight its importance. 
​The phrase "and I can't do a thing with it" is referring to a pen that now cannot be used, having been damaged by water. This is often taken as a pen accidentally left in clothing and washed, however, it may have a more sinister implication. 
The threat of "I could do my Thing," is obviously referencing murder- but by parroting the word "thing" from the card, which is explicitly referencing the pen, the Zodiac Killer may be associating the pen with murder. More specifically, the murder of Cecelia Shepard.  
The Zodiac Killer's dominant hand would certainly have been covered in blood after the Lake Berryessa double stabbing, so any pen subsequently used to write on the car door would equally have been smothered in blood, thereby making the November 8th 1969 'Dripping Pen' card, of a washed pen, not an unusual choice by the killer. The killer may have worn gloves and removed them before writing on the car door, but the implication of the card remains. 
The six exclamation marks after the word "Thing" are as notable, as they are excessively repetitive. The Zodiac Killer has also deliberately or accidentally underlined the word "Thing" exactly six times. These two characteristics may be purely unintentional on behalf of the author, but considering the Zodiac Killer is claiming 7 victims at this juncture, it would be remiss not to mention that the Lake Berryessa murder of Cecelia Shepard would have been the Zodiac Killer's sixth victim.
One theory behind the origin of the exclamation mark, is that it is derived from a Latin exclamation of joy, which may not have been lost on a killer bereft of empathy.