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. 

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

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

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

Michael Cole wrote an excellent article entitled "My Name Is" Cipher Motivation that suggested the Zodiac Killer likely drew his inspiration for the '13 Symbol' cipher from an October 22nd 1969 newspaper article by Will Stevens, which laid down a challenge to the Zodiac Killer from the president of the American Cryptogram Association (ACA), Professor D.C.B. Marsh, to reveal his name. Apparently, several months later the killer duly obliged by opening his correspondence with the line "This is the Zodiac speaking. By the way have you cracked the last cipher I sent you. My name is...." 
He followed this by placing 13 characters underneath, widely believed to be the Zodiac Killer offering us his name. 
One couldn't help considering whether this cipher was not only created because of the newspaper article, but whether this cipher was created based on what was contained within the article- in particular the works of Edgar Allan Poe. This would be right up Zodiac's alley, devising a cipher based in the text of the newspaper article. 
Here is an excerpt "Dr Marsh told the Examiner today: "The killer wouldn't dare, as he claimed in letters to the newspapers, to reveal his name in the cipher to established cryptogram experts. He knows, to quote Edgar Allen Poe, that any cipher created by man can be solved by man. Zodiac has not told the truth in his cipher messages to the Examiner, the Chronicle and the Vallejo Times-Herald. Zodiac has not done this, because to tell the complete truth in relation to his name-in cipher code-would lead to his capture. I invite Zodiac to send The American Cryptogram Association a cipher code, which will truly and honestly include his name."

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

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

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

For many years, some observers have questioned the September 27th 1969 Lake Berryessa attack on Bryan Hartnell and Cecelia Shepard as a genuine Zodiac crime. It is claimed that the MO of this crime wasn't like Zodiac, despite the fact he altogether only committed three other confirmed attacks, in which Presidio Heights, one could argue, wasn't his MO either. The amount of crimes ascribed to the Zodiac Killer isn't a large enough sample size to make such astronomical claims based on modus operandi. 
Some people also believe that the attacker at Lake Berryessa intended to leave at least one victim alive (in this case Bryan Hartnell), because murdering both would have negated the wearing of the costume. This argument carries no weight whatsoever.
​Bryan Hartnell was bound hand and foot approximately 510 yards from the nearest roadway  (Knoxville Road)- and was brutally stabbed in the back six times, which resulted in extensive blood loss. In the 2007 Zodiac documentary he recalled his memories of the fight to live,:after struggling to free himself from the clothesline bindings: 
"So I got up and made it about 5 feet and the sparkles and the darkness came back and I had to drop down immediately to keep from passing out. I'd just lost too much blood and had no energy to move. So I waited a minute, got some more strength, and thought I'm going to have to do this a little slower. I made it another five feet and dropped down myself. So I started just taking 5, 10 feet intervals, and found that if I wasn't trying to walk fast and walked bent over holding my chest and walk slower, I could make more distance in between having to stop and rest. I made it about halfway to the road and saw some lights coming." This is where he was eventually aided by park ranger Dennis Land. 
At approximately 7.10 pm or very shortly after, Sgt William White radioed Park Headquarters to summon an ambulance and deputies to the crime scene. An ambulance from Naps arrived at the crime scene at approximately 7.55 pm, and returned back to the Queen of the Valley Hospital, arriving at 8.50 pm. That is an approximate journey time of 45 minutes each way, including 10 minutes negotiating the crime scene.

Therefore, one would have to assume that the attacker with an extensive knowledge of anatomy, surgically delivered the knife wounds to Bryan Hartnell, knowing he would free his bindings and would be discovered by a third party in a particular amount of time- and in addition- factor in the overall time the ambulance would take to arrive at the crime scene and return to the hospital. Furthermore, calculating the blood loss to be suffered by Bryan Hartnell in order for him to be subsequently saved by the hospital surgeons and thereby recount his experience of being attacked by a costumed slayer with crosshairs on his chest. I doubt this is a realistic proposition.
It is clear the Zodiac Killer or copycat intended to kill both Cecelia Shepard and Bryan Hartnell, and thought he had- evident by the phone call placed in Napa approximately 70 minutes later, in which the killer stated "I want to report a murder, no, a double murder. They are two miles north of Park Headquarters. They were in a white Volkswagen Karmann Ghia. I'm the one that did it".
​So, why did the attacker wear a costume with crosshairs on the front, if he had no intention of leaving the couple alive?
The Zodiac had every reason to wear the crosshairs symbol, but the copycat didn't.
The attack took place during daylight hours at 6.30 pm or slightly earlier- so the killer, whether Zodiac or copycat, had good reason to wear a costume or disguise in case he was spotted by any eyewitnesses- something I'm sure he was keen to avoid. 
For those in the copycat camp, the writing on the car door of Bryan Hartnell's 1956 White Karmann Ghia and the telephone call to police dispatcher Dave Slaight, is not sufficient proof it was the Zodiac Killer- because the style of the handwriting on the car door and composition of the message in the phone call (based on the Blue Rock Springs call) were widely available in many newspapers- and could easily have been reproduced by a copycat. It is therefore imperative we find another reason to tie the Lake Berryessa attack to the Zodiac Killer rather than a copycat. 
Bryan Hartnell stated that the assailant wore a black hooded mask made of a cloth material, covering his entire head and shoulders, reaching down to the waist. On the front of the four cornered mask at the chest area was a white circle (3 x 3 inches inches in diameter) and a symmetrical cross. He would further elaborate on the design of the crosshairs, as well as later in the 2007 Zodiac documentary, stating "It looked like it was made with a machine or with some degree of care- it wasn't just scrawled on with white paint. It was proportional."       

Why would a copycat killer meticulously sew on perfectly symmetrical crosshairs onto a carefully crafted costume, when he had no intention of leaving anybody alive to report it. If the crime had been committed by a copycat, then imitating the Zodiac Killer's writing on the car door and subsequent phone call should have sufficed. He could simply have disguised his features with a mask or plain hood. 
The same could be said of the Zodiac Killer, I hear you saying.
However, there is one big difference.
The Zodiac Killer had murdered three and seriously injured a fourth person at this juncture, and had bathed in the spotlight of numerous newspaper articles in his name. This must have fed his egotistical nature, and in his own mind, elevated him to another level of self-aggrandizement. The idea, that he would then carefully craft a costume befitting of such an infamous and feared villain, doesn't seem that far-fetched. Would a copycat spend this much time creating an elaborate costume, bedecked with crosshairs, when nobody was going to be left alive to report their observations to police? It would be a pointless waste of time. A copycat would have just reproduced the handwriting on the car door and made the payphone call. The Zodiac Killer, on the other hand, had every reason to adorn himself with a costume befitting of the man he thought he was.

Tom Voigt, creator of the hugely successful ZodiacKiller.com website has been striving to secure Zodiac material previously withheld from the public for many years. Authenticated by a state document examiner, the DMV letter was mailed to the chairman of the California Department of Motor Vehicles, yet its delivery date and contents have remained elusive to this day. It appears the overriding consensus, is that the closer this correspondence was mailed to the four canonical crimes, the more likely it is to be genuine Zodiac material. Having read the limited forum threads on this topic, the murder of taxicab driver Paul Stine in Presidio Heights on October 11th 1969 comes to the fore.
Tom Voigt stated "While I don't yet have as many details as I would like, at some point the Zodiac wrote a letter to the chairman of the Department of Motor Vehicles (DMV) in California. The letter was authenticated, apparently via handwriting, and was kept quiet for reasons unknown. The reason I have only lately been attempting to get permission from my source is because I just recently learned from victim Paul Stine's sister that Paul's wife at the time of his murder worked for the DMV". 
There is a California Department of Motor Vehicles at 1377 Fell Street, San Francisco, the same street that Paul Stine resided (1842 Fell Street) and just 700 meters away- but whether the suspect letter was mailed to the San Francisco offices and forwarded to the Department of Justice in Sacramento, or mailed directly to Sacramento, maybe Tom can elaborate.       
The Paul Stine police report suggested that the "suspect may also be in possession of the keys to the Yellow Cab, and possibly has the wallet belonging to the victim," so whether the Zodiac Killer mailed any possessions of Paul Stine with his communication to the DMV  chairman is uncertain. Having no idea the date this letter was mailed, opens up the possibility it may be connected to the Lake Berryessa attack on September 27th 1969, the only confirmed Zodiac crime in which the killer seemingly failed to document in letter form.

Having left his message on the car door of Bryan Hartnell's 1956 White Karmann Ghia, it is not unrealistic to consider that any correspondence following this crime may have been automobile related, hence the connections being drawn to the California Department of Motor Vehicles letter. Tom Voigt stated that "Paul's wife at the time of his murder worked for the DMV," but can we connect a possible Zodiac victim to the California Department of Motor Vehicles in or around the five murders attributed to Zodiac.

​On Saturday February 21st 1970, five months after the Paul Stine murder, John Franklin Hood (24) and Sandra Garcia (20) had traveled to East Beach, Santa Barbara, near East Cabrillo Boulevard- with John telling his parents he was to spend the day with his fiancee. Sandra had informed her parents that they "wouldn't be gone long," however, when they didn't return home that night the families became understandably concerned.
Their bodies were discovered early Sunday morning by beachgoers, fully clothed underneath a blanket. They had been brutally beaten and stabbed, predominantly in the back and face.
​John Hood had been stabbed eleven times, but it appears Sandra Garcia suffered the brunt of the attack, not dissimilar to the senseless attack on Bryan Hartnell and Cecelia Shepard at Lake Berryessa on September 27th 1969. Had the Zodiac Killer returned to a familiar method of execution after his venture into the heart of San Francisco, and was the Melvin Belli letter on December 20th 1969 the foreboding of a man who was about to murder once again, stating he may "lose control again and take his ninth or possibly tenth victim." Were John Franklin Hood and Sandra Garcia those victims. 
"The eldest of six children, Hood was born in Seattle. He came to California with his family in 1950. He attended El Rio Elementary School and graduated from Camarillo High School in June, 1965. After graduation, he worked at Wimpy's Drive-In in Oxnard and then joined the Army in January 1966. He spent two years in Germany with the 64th Armored Division after boot training in Ft. Bliss, Texas, and then returned home for leave before being sent to Vietnam. While on leave, Hood met Sandra while they were both vacationing in Tijuana, Mexico. An expert marksman, Hood was sent to Vietnam on January 6, 1969 with the 64th Armored Division. Hood was closed-mouthed about the combat-filled year he spent there and about the Silver Star, Bronze Star, Purple Heart and other medals he had received for valor. After returning to Oxnard, he went back to work for the drive-in eatery. Although Hood and Sandra were planning to be married, they had not set a wedding date." Oxnard Press Courier, February 23, 1970. Sandra Garcia worked for the California Department of Motor Vehicles in Oxnard, Santa Barbara.
​Was the DMV letter claiming this double murder, but was withheld from publication by police, who were unsure of a connection to the Zodiac Killer, or because of the sensitive details contained within the communication. We may have to wait a little longer to find out. 

FOOTNOTE: On September 12th 1987, Jose Santo Bugarin (26) and Rodolfo Alvaro (31) were traveling on King Road, San Jose, California when their car slammed into four children playing on the front lawn of a residence, killing three and injuring one. The driver then backed over the bodies and left the scene. Both were apprehended a short time later. "Bugarin was arrested on three counts of second-degree murder. Alvaro also was arrested on murder charges." Chicago Tribune.  
This was covered extensively in the newspapers. Just over six weeks later a letter claiming to be from the Zodiac Killer was mailed to the Vallejo Times-Herald on October 28th 1987​.
Update: "SAN JOSE (AP) A man who ran over and killed three children entered a plea bargain on Wednesday, pleading no contest to second degree murder and two vehicular manslaughter charges. Jose Santos Bugarin, 26, of San Jose, had two of the original murder charges filed against him changed to manslaughter. He will be sentenced to 21 years and eight months in state prison. Bugarin was the driver of a car that plowed through a front yard on King Road in San Jose on Sept. 12, killing three children." San Bernardino Sun- December 3rd 1987.
​Did the Zodiac Killer or the author of the 1987 letter read the news stories of this senseless crime and callously draw inspiration from this tragedy (Cars make nice weapons), compelling him to write the above correspondence, piggybacking off newspaper articles, in not dissimilar fashion to his early communications. 
The Car movie featured a satanic driverless car running people over in the fictional desert town of Santa Ynez in Utah. IMDB.
However, Santa Ynez is not so fictional in California. The town of Santa Ynez is one of the communities of the Santa Ynez Valley, Santa Barbara.  It is situated just 20 minutes or 12 miles (as the crow flies) from the site of the Robert Domingos (18) and Linda Edwards (17) murders on June 4th 1963, widely touted as an early Zodiac crime. See article 'Death on Four Wheels'. 

Thanks to Tom Voigt at ZodiacKiller.com

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.      

The following is based on a very interesting post by Mike Morford on the Zodiac Killer Site forum.
Just past midnight on Sunday November 2nd 1975 a man walked up to a couple's vehicle on Monte Cresta Drive, Belmont, California and shot 17 year-old Carlmont High School student Anthony Vincent Bruno Jr to death. "According to Police Captain George Stephenson, Bruno and his girlfriend (16 years) had been parked on Monte Cresta Drive, above Barclay Way in an isolated area of western hills when a man opened the driver's side door and apparently without saying anything fired the shotgun. The girl, who was not identified by police, pushed Bruno's body aside and drove the car to her home from where police were notified. She described the assailant as white, 5 feet 5 inches tall, 140 pounds and wearing an Army green parka with hood, according to police. Stephenson said also that a late model brown pick-up truck, possibly a Dodge or Chevrolet, had been seen in the area at about the time of the shooting."
San Mateo Times.
Anthony Vincent Bruno was shot in the mouth from close range while the couple were parked on the rise of a hill, described as a lovers lane area. The weapon (believed to be 25+ years old and not made now) malfunctioned when the cut-down stock of the shotgun broke free from the weapon and was found 10 feet from the scene of the crime. The police said it had been taped to the barrel. "The killer then ran south on Monte Cresta from the dark hillside area, past a streetlight 50 yards away, and then possibly to a late model Dodge or Chevrolet pick-up truck." The area of isolated hillside continued for several hundred feet, ending in a dirt road. Here is a newspaper cutting from the actual crime scene and its modern day equivalent on Google maps.

A follow up San Mateo Times article dated December 11th 1975 stated 'The youth, Anthony Vincent Bruno of 213 Bayview Drive, San Carlos, died instantly, his body sprawled on the seat of the parked car beside his terrified 16 year-old girlfriend. The killer then turned, dropped the sawed-off stock of his weapon on the ground, perhaps by accident, and fled. It was disclosed Wednesday that about an hour and a half before the brutal slaying, a man was seen struggling to drag a box about two feet long and 18 inches wide up a steep rise about 100 feet from the slaying site. A rod, or perhaps a rope, protruded from the box, according to police, and the dragging was being done by a man in mechanic's overalls with longish, dark brown hair. Stephenson also confirmed that police are searching for the driver of a maroon pick-up truck, equipped with blackwall tires and white wheels; a vehicle which they have information to believe may have approached the parked couple 15 minutes before the slaying, stopped a distance away, made a u-turn, and apparently drove off.' The girl gave a follow up description "She saw a face but couldn't identify him. She couldn't see whether he was black or white, or anything other than he was 5'5", 140 pounds and wearing a green army-type parka."        

"We've never had a case like this before. This is the bloodiest, most brutal killing I've ever seen", Belmont Police Chief William R Singer said as he surveyed the scene of Belmont's first potential murder case in over two years. "It could be another Zodiac", he added. '
Whether the description of the killer is accurate or not, it is an interesting addition from Mike Morford. The couple were attacked on an isolated lovers lane area while parked up in their vehicle at around midnight, the killer may have approached their vehicle, left and returned 15 minutes later, not unlike the Blue Rock Springs Park attack on Darlene Ferrin and Michael Mageau, the attack appeared motiveless, and probably the most important thing of all, we shall come to at the foot of this article.
'Wednesday afternoon, Juvenile Division Detective Gary Sickman drove this reporter to the scene of the slaying and replayed what police have linked together about it so far. "This is a little-known lovers' lane", Sickman said. "Many of the kids I've talked with at Carlmont were unaware of it." 
Sickman drove the patrol car down a narrow dirt road connecting with Monte Cresta Drive; a chuckhole-pocked stretch traversing a ridge high above Belmont Canyon. At the end of the road, a half-mile from the slaying site, a teenaged couple embraced in a parked car. Sickman checked their identification and jotted their names in his notebook after giving them a little fatherly advice.'
This murder was the first in Belmont in over two years. The Zodiac Killer's last confirmed communication was on January 29th 1974, although there were possible Zodiac communications up to July 8th 1974 with the 'Red Phantom' letter. There would have been hoax letters purporting to be the Zodiac Killer subsequent to this, but one would assume the 'novelty' of Zodiac would have worn off in time and the hoax letters would have dropped off in frequency by the November of 1975. That is what makes a letter purporting to be from the Zodiac Killer, found in a phone booth likely on the day of the murder, all the more interesting. 
​Mike Morford stated, in reference to a San Mateo news article dated November 14th 1975 "The reporter, a man named Bob Foster, mentions that on the night of November 3, 1975, the 11 pm TV news on channel KGO, ran a story about a Zodiac letter being found in a phone booth. This is pretty interesting to me for a couple reasons regarding the timing.
First of all because, the night before, on 11/2/75, a young man and his girlfriend were attacked on a lovers lane by a gun wielding man. The male victim, Vincent Bruno was killed, but his girlfriend survived. If I recall correctly, there may have been a letter & cassette tape found the same night in a phone booth not far from the attack site, from someone claiming to be Zodiac."
I would like to thank Mike Morford for the information regarding this story. All images are courtesy of the Zodiac Killer Site forum and the San Mateo Times. Here is a link to the thread on Mike Morford's site.