Recently it has been shown that the Zodiac Killer fashioned the October 6th 1970 "13-Hole" and October 17th 1970 "Edward Adams" postcards by using significant parts of the "Letters to the Editor" page from the San Francisco Chronicle in each instance. The question has always been, did the Zodiac Killer know (or come across) Edward C. Adams, his wife, or any of their family members? After all, the October 17th 1970 postcard was mailed directly to Edward C. Adams at 102 Camino Don Miguel, Orinda, California, and postmarked Berkeley, just a few miles west of his home. The threat of "ADAMS YOU ARE NEXT" could be interpreted that Edward C. Adams, having recently experienced a death in the family, was next for the afterlife.

This was the route explored by excellent Zodiac researcher Mike Morford when he found and posted a newspaper article on the Zodiac Tapatalk forum earlier this year, announcing the death of Florence Wolcott on October 14th 1970, the mother-in-law of Edward C. Adams, who died three days before the "You Are Next" postcard was postmarked. Mike Morford stated that the postcard was created on October 12th 1970, but that isn't necessarily the truth, because the postcard was only fashioned from San Francisco Chronicle newspaper cuttings from that date and very probably mailed four or five days later. The Zodiac Killer could have taken cuttings from the October 12th 1970 San Francisco Chronicle newspaper at any time between October 12th and October 17th.

​Every newspaper cutting, apart from the large capitalized "YOU", can be found in the October 12th 1970 newspaper (the search function easily finds black text but not white). However, despite trawling through every page manually, I have yet been unable to locate the "YOU" on this specific date. Either I have missed it, or it may be present in the San Francisco Chronicle pages between the dates of October 12th and 17th, or another publication. If the "YOU" (on a dark background) can be found in the San Francisco Chronicle newspaper after the death of Florence Wolcott and before the time the Edward Adams postcard was mailed, it could bolster the case for this communication being a response to her death. Mike Morford speculated on whether someone knew that Edward C. Adams' mother-in-law was on "her last legs" and imminent for death, responding in this callous manner on October 17th 1970. The timing of her death just three days before the mailing date, the threat of "You Are Next", and the knowledge of Edward C. Adams' home address could suggest some familiarity with this family.

The newspaper article shown above is from the Orland Unit Register from October 15th 1970, so what is the likelihood that the Zodiac Killer came across this article? Orland is a city 110 miles northeast of Vallejo (by crow) which had a population of 2,310 in 1970, so if he was knowledgeable about the death of Florence Wolcott, isn't it more likely he got the news direct from the family, or somebody close to them?

THE EDWARD ADAMS POSTCARD WAS MAILED BY ZODIAC

If you believe that the "13-Hole" postcard was mailed by the Zodiac Killer on October 6th 1970 (which I do), it is with absolute certainty that he mailed the Edward Adams communication on October 17th 1970 from Berkeley, California. The postcard, affixed with newspaper cuttings, read "Mon Oct 12, 1970. Edward Adams. The Zodiac is going to change the way of committing murders. I shall announce when I shall commit my murders, The Adamses are Next. you taught me to Mean it. ADAMS YOU ARE NEXT. Zodiac".

The section in blue was taken from the breaking news story about the Zodiac Killer on page 5 of the October 12th 1970 San Francisco Chronicle  The newspaper was reporting on the "13-Hole" postcard and the previously withheld "Little List​" letter mailed on July 26th 1970. The 8 words in red were all taken from a column on page 38 entitled "Question Man By O' Hara", just to the right side of the "Letters to the Editor" section. When I typed in a search for the word "taught" in the San Francisco Chronicle on October 12th 1970, it appeared only on page 38 in the "Question Man" column (shown below), followed by the other 7 words in the same column, which Zodiac used to spread haphazardly over his Edward Adams postcard. The 8 words can all be found in these two small responses to the "Question Man" below. The uppercase "M" in "Mean" can be found on the same page in the name "Abe Mellinkoff" just to the left of these responses.

​In the upside-down text of the "13-Hole" postcard, the Zodiac Killer created 17 words from the September 23rd 1970 San Francisco Chronicle "Morning Report" by Abe Mellinkoff, and one word from the column "Question Man By O' Hara". In other words, the Zodiac Killer created a total of 18 words he sourced from the "Letters to the Editor" page on September 23rd 1970, which he used on his "13-Hole" postcard, and created 8 words and the letter "M" from this very same page on October 12th 1970, which he used on his Edward Adams postcard. Therefore, Abe Mellinkoff and "Question Man By O' Hara" featured in both postcards. That's because they were designed by the same person.     

The Zodiac Killer often referred to the "Editor" in his communications, including the "13-Hole" postcard, so it isn't surprising that a large quantity of newspaper cuttings were sourced from the "Letters to the Editor" page from the San Francisco Chronicle newspaper on September 23rd 1970 and October 12th 1970. Here is the upside-down text from the "13-Hole" postcard, which read "There are reports city police pig cops are closeing in on me. Fk I'm crackproof. What is the price tag now". Everything in red can be sourced from this single article by Abe Mellinkoff on page 54 of the San Francisco Chronicle on September 23rd 1970 (shown below)..See the recent article More on the "Pace" Postcard Cuttings for a more detailed explanation.

Below are the two pages from the San Francisco Chronicle on September 23rd 1970 and October 12th 1970, that the Zodiac Killer mined heavily for his newspaper cuttings to paste onto his "13-Hole" and Edward Adams postcards. This proves without a shadow of doubt that the Zodiac Killer was responsible for both communications.  

It was easy for the Zodiac Killer to find the "Adam" (and his signature "Zodiac") he used in "Adamses" because it was present on the front page of the October 12th 1970 San Francisco Chronicle next to his own story. The "ses" was located by searching for "passes" in the multiple sports pages covering American football. The surname "Adams" was also easily found in the sports pages. The forename of "Edward" was present in a story about Edward M. Kennedy on page 8. Bearing in mind that the Zodiac Killer showed an interest in Gilbert & Sullivan's "The Mikado" and films, it would probably have been apt had he chosen the word "Next" from page 43 featuring a Gilbert & Sullivan opera by the The Lamplighters and the cinema section. It was located in the listings of Bay Area Movies in the advertisement for the Albany Cinema at 1115 Solano Avenue in Berkeley, the very location that the Edward Adams postcard was mailed from. However, because of the "N" font, it appears that "Next" was sourced from the sports pages yet again.

​The surname "ADAMS" in uppercase letters can be found on page 30, in addition to "ARE" in two car advertisements (shown below). The large "YOU" with a dark background may be from another publication, because in some images of the Edward Adams postcard it appears a different style background (see the attached image on the right to see this difference).    
​EXTRA READING: THE "PACE" POSTCARD AUTHENTIC 
FOLLOW UP ARTICLE: THE SEARCH FOR "YOU" IN PRINT 

The newspaper coverage regarding the disappearance of Donna Lass began on September 22nd 1970 and continued with a flurry of articles until the end of the month. This was the period of time the Zodiac Killer was constructing his "13-Hole" postcard taking cuttings from the San Francisco Chronicle (September 23rd 1970), San Francisco Examiner (September 25th 1970) and Oakland Tribune (September 25th 1970). We know that the Zodiac responded to recent newspaper coverage about himself and random stories, so was he manufacturing and designing the "13-Hole" postcard in reponse to the unfolding story of Donna Lass.

​It had been documented that somebody claiming to be the Zodiac Killer had already contacted Incline Village (and other areas nearby), threatening to target school buses in late November and the first half of December.of 1969, which predated by over a year the Zodiac Boise Cascade advertisement at Incline Village, that he used in his "Pines" postcard on March 22nd 1971. If the threats to the Lake Tahoe region lasting several weeks in 1969 were the Zodiac Killer, then he had every reason to be following the story of a missing woman in Lake Tahoe in 1970, whether he was her murderer.or not. He would also have threatened several "Lake Tahoe areas" in 1969 before telling us to "pass Lake Tahoe areas" on March 22nd 1971. In fact, the Sacramento Bee newspaper article on December 15th 1969 just happens to contain the words "passed", "Lake Tahoe" and "areas" (shown below in blue)..

The "13-Hole" postcard, postmarked October 6th 1970, not only contained a running victim total of 13 to mirror his count on July 26th 1970, but he added a red crucifix directly underneath. The number 13 had a small line extending from the newspaper cutting on its bottom face, as if to indicate that the crucifix may play a role in the victim total. Was the Zodiac Killer expressing that he had currently killed 13 people to date, with one victim yet to be found, which he symbolized by the addition of a grave marker in the form of a crucifix?

​This was the only time the Zodiac Killer added a crucifix to his communications, and the only time he would have been playing into the narrative of a victim still currently alive and missing in the eyes of law enforcement. One can only speculate on its purpose, but if the Zodiac Killer had murdered Donna Lass and buried her in a grave at Yuba Gap in Placer County, the crucifix could signify a burial site. The Zodiac Killer, by not adding Donna Lass to the running total in the conventional manner, could have been the precursor to the game he would ultimately play 5 1/2 months later. A game that possibly came to fruition when he mailed the "Pines" postcard on March 22nd 1971 and added a fourteenth punch-hole in sinister fashion. 

A red crucifix most often represents the blood of Christ and the sacrifice of his crucifixion. In this instance, the Zodiac Killer may have been using this color to depict the murder of Donna Lass and a burial marker to his fourteenth victim, that he would cryptically suggest on October 27th 1970, and further elaborate upon on March 22nd 1971. However, did the red crucifix have a dual purpose as a red cross, bearing in mind Donna Lass was a nurse. The relationship between the Red Cross and nursing dates back to the influence of Florence Nightingale, who inspired the organization's founding and subsequent work in wartime and disaster nursing. Historically, nurses wore the Red Cross emblem for protection under the Geneva Conventions, though this is now rare outside of armed conflict. The Red Cross has a long-standing and deep connection to nursing in America, dating back to its founder, Clara Barton, a nurse and humanitarian. The American Red Cross relies heavily on the expertise of nurses and other health professionals as volunteers and staff to support disaster relief, community health initiatives, and blood drives. 

Irrespective of these speculative offerings, we definitely have a "Zodiac" threat on school buses around Lake Tahoe in 1969, a "13-Hole" postcard being designed by the Zodiac Killer the day after the disappearance of Donna Lass from Lake Tahoe was reported in the newspapers, and a "Pines" postcard stating "pass Lake Tahoe areas" with a further punch-hole. If the Zodiac Killer had sourced all his cuttings from the newspapers for the "13-Hole" postcard by September 25th 1970, why did he wait over a week into October to mail this communication? Was he waiting for the news stories of Donna Lass to fade away, to see if anything needed to be added to the postcard?

The prolonged threats toward school buses and schools in Lake Tahoe over several weeks in November and December 1969 mirrored the "Zodiac" threats toward school teacher Daniel Williams, which lasted from October 23rd 1969 to November 5th 1969. If they were hoaxers, they were certainly persistent ones.   

MORE ON THE "PACE" POSTCARD CUTTINGS ​

A while ago I wrote an article on the newspaper sources used in the construction of the October 6th 1970 "13-Hole" postcard, unearthed by many different contributors. Jarrett Kobek, author of "Motor Spirit" and "How to find Zodiac", identified the September 23rd 1970 San Francisco Chronicle article that contained the upside-down text of "THERE ARE REPORTS".. So I did a little extra digging and found that the overwhelming majority of the upside-down text can be found in this article (shown below).  The upside-down text read "There are reports city police pig cops are closeing in on me. Fk I'm crackproof. What is the price tag now". Everything in red can be sourced from this single article on page 54 of the San Francisco Chronicle. The word "I'm" can be found next to this article on page 54. On page 53 we can find "What is" (with the uppercase W). And on page 29 we can find "the price", "The price" and "double in price" (in darker print). However, these two words were not cut out together, so it's clear that the Zodiac Killer, knowing the message he wanted to send, originally sourced (and possibly pasted) the word "the" from the article below, before flicking back through the pages to the "Business Section" he had already read in order to find the word "price". This would have been the likeliest page to find this word. It can be found on page 53 along with "What is", so this is an option too. Everything in the upside-down Zodiac text was therefore sourced from three pages of the San Francisco Chronicle newspaper (pages 29, 53, 54). It must be noted that the word "pig", "closeing", "crackproof" and "tag" were all created using two cuttings (or more). 

The rest of the newspapers identified for the remainder of the text on the "13-Hole" postcard were found by Vasa Croe, Brubaker, Cragle and Jibberjabber. If I've missed anybody, please let me know. In total, three newspapers were identified: The San Francisco Chronicle on September 23rd 1970, The San Francisco Examiner on September 25th 1970 and the Oakland Tribune on September 25th 1970. These cuttings were sourced from newspapers published just one and three days after the news broke about the disappearance of Donna Lass from the Sahara Tahoe Hotel & Casino at Lake Tahoe. Donna Lass went missing on September 6th 1970, the newspapers first reported her disappearance on September 22nd 1970, and the upside-down text was sourced from the San Francisco Chronicle on September 23rd 1970. So was the "13-Hole" postcard a response to the abduction of Donna Lass?

​In an earlier article I examined the upside-down text "around in the snow" on the "Pines" postcard, believing that it may have signified the area where the body of Donna Lass could be found - and if we righted this text through 180 degrees by turning the postcard around, the "Sierra Club" pasting (Clair Tappaan Lodge) and the punch-hole would likely identify the location of Donna Lass' burial site. I believe it did to incredible accuracy. The upside-down text for the "13-Hole" postcard was sourced from the San Francisco Chronicle on September 23rd 1970, which was the day after her disappearance from the Sahara Tahoe Hotel & Casino was first reported in the newspapers. So was this text sourced with the express purpose of highlighting something about Donna Lass? The "13-Hole" postcard and "Pines" postcard both had inverted text and punch-holes.

Were the 13 punch-holes on the "13-Hole" postcard signifying the burial sites of his 13 victims? The Zodiac Killer victim total hadn't increased from July 26th 1970 to the time the "13-Hole" postcard arrived at the San Francisco Chronicle, so why didn't the Zodiac Killer increase his victim count in October to include Donna Lass from September 6th 1970, if he was her murderer? Was it because she was only currently recognised as a disappearance and the Zodiac Killer wanted to play games with law enforcement, which he would ultimately achieve when he mailed the "Pines" postcard on March 22nd 1971? Or was he writing "13" on the postcard as confirmation, because his July 26th 1970 letter claiming the same number of victims, was not currently published in the newspapers.   

But what was the article about on page 29 of the San Francisco Chronicle on September 23rd 1970, the day after Donna's disappearance was first reported in the newspapers, that the Zodiac Killer may have sourced to use the word "price" for his upside-down text on the "13-Hole" postcard? The Zodiac Killer had three choices on the same page. One was about the Sanoma mines, one was about stock prices, and the other was about the Boise Cascade Corporation, the very company whose advertisement he had used on the "Pines" postcard on March 22nd 1971. Therefore, a fighting possibility exists that the Zodiac Killer used a cutting about the Boise Cascade Corporation for both postcards, indelibly linking them together.  

As pointed out earlier, the Zodiac Killer also took cuttings from the Oakland Tribune on September 25th 1970, three days after Donna Lass was reported missing. If the Zodiac Killer had buried Donna Lass west of Clair Tappaan Lodge and the Boise Cascade Corporation developments at Incline Village, did he select the word "price" from the above page of the Chronicle newspaper article, knowing that he would later mail a cryptic postcard mentioning the "Lake Tahoe areas" and provide us with a further cutting from the Boise Cascade Corporation, but this time with directions to her remains? Even if the word "price" was not sourced directly from the Boise Cascade article above, and he instead opted to cut the word "price" from the darker "double in price" text on page 29, he would still have used two San Francisco Chronicle newspaper pages containing Boise Cascade articles to fashion both postcards. When the San Francisco Chronicle published this advertisement about Boise Cascade at Incline Village on March 19th 1971, did the Zodiac Killer seize his opportunity and decide to reveal the burial site of Donna Lass?. The Oakland Tribune on September 20th 1970 also ran an article about the Boise Cascade Corporation (see below). However, they mentioned "Incline Village", five days before the Zodiac Killer may have taken "price" from a Boise Cascade newspaper article, six months before he mailed a postcard on March 22nd 1971, using a Boise Cascade advertisement depicting Incline Village. .     

The April 20th 1970 letter opens with "This is the Zodiac speaking. By the way have you cracked the last cipher I sent you? My name is....". One of the takeaways from the mention of his previous cipher while beginning this communication, has been that something about that previous cipher may aid in the solving of the current Z13 code. Many have taken the code key from that now solved 340 cipher and tried to apply it to the Z13 code. While some of those attempts have produced interesting outcomes, they have all required some form of manipulation to generate a desired result, which leaves room for objection. But what if the answer or key lay in the unsolved 340 cipher at the time Zodiac mailed his Z13 code on April 20th 1970. Bearing in mind this latest letter was suggesting that the Z13 code would reveal a "name" or "identity", it is quite possible that his identity in the unsolved 340 cipher held the clue.

In the 340 cipher on the final line he appeared to give us his signature of ZODIAC from characters 333 to 338. However, he replaced the "D" with a blackened triangle, reversed the "I" and "A", and changed the "C" for a "K". Despite this, it's unmistakable presence is there for all to see. What if we took this identity to solve the Z13 code.  

As stated previously, Professor Donald C. B. Marsh invoked the name of Edgar Allan Poe to challenge Zodiac to reveal his name on October 22nd 1969, hoping that the Zodiac Killer would utilize the cryptographic works of Poe to create any forthcoming ciphers. Taking one look at Poe's essay, "A Few Words on Secret Writing" in the July edition of Graham's magazine, you can see the scytale method of decryption that can be used to solve Zodiac's 340 cipher, the cryptographic technique of splitting of the alphabet A through M and N through Z, which Zodiac employed in his design of the Z13 code, and the cipher wheel explained by Poe, which not only decodes the "near Zodiac" on the final line of the 340 cipher to give us the key, but provides us with a resulting key that the Zodiac placed directly into his 13 characters on April 20th 1970, that generates an answer he would later reveal as his signature on January 29th 1974. That signature was "Me". 

The "near Zodiac" in the 340 cipher has simply been manipulated using a cipher wheel. When we compare the correct spelling of ZODIAC to the version supplied on the final line of the 340 cipher, we can see that Z to Z, O to O, and D to triangle generates no difference alphabetically (000). Whereas "IAC" to "AIK" generates a shift of 8 positions for each letter, producing 888. This provides us with 000888, the possible origin of the three circled 8's in the Z13 code. Visit the Caesar cipher wheel here and type in the number 8 (see below). The inner wheel will spin 8 positions clockwise so that the outer wheel "I" is represented by the inner wheel "A" (and vice versa). The outer wheel "K" is represented by inner wheel "C" (and vice versa). This is the bedrock of the switch from "IAC" to "AIK" in the spelling of ZODIAC. If we place the 13 characters from the April 20th 1970 letter within a cipher wheel (shown above), forming an inner and outer ring, and then spin the inner wheel clockwise by 8 positions, the three circled 8's land over "ME" and the "crosshairs". The signature he chose to use in the "Exorcist" letter on January 29th 1974, created by a technique described by Poe in "A Few Words on Secret Writing".    

But how do we know that the three circled 8's are the key to solving the Z13 code? In the April 20th 1970 letter the Zodiac Killer wrote "This is the Zodiac speaking. By the way have you cracked the last cipher I sent you? My name is....", followed by 13 characters. The next time the Zodiac used the verb "to crack", is when he told us he was crackproof in the 13-Hole postcard at the beginning of October 1970, five and a half months later. The Zodiac Killer stated "Fk I'm crackproof" and punched 13 holes into the fabric of the postcard. But just like the April 20th 1970 letter featured three circled 8's in a configuration of 13 characters, the postcard in October separated out three punch-holes from the other ten. These three punch-holes were positioned almost directly below the positions the three 8's slotted into the Z13 code (see below). In other words, pull the three 8's downwards from the Z13 code and you get the 10:3 configuration shown in the 13-Hole postcard.  

Was the Zodiac Killer highlighting the three punch-holes (888) from the total of 13 to show that these were the key to solving the "crackproof" Z13 code on April 20th 1970? In total, we have the three circled 8's generated by a cipher wheel from the "near Zodiac" in the 340 cipher, placed into the Z13 code five months later, which by using a cipher wheel once again, generated the signature of "Me" from the Z13 code, that is present as the signature in the Exorcist letter on January 29th 1974. The Edgar Allan Poe essay "A Few Words on Secret Writing", featuring the cipher wheel, the scytale method of cryptography, and the technique of splitting the alphabet into 13 characters, which are all integral to the solving of the 340 cipher and the possible design of the Z13 code, may very well have been chosen because of the challenge by Marsh on October 22nd 1969. He wanted the Zodiac Killer to send a cipher to The American Cryptogram Association that would honestly include his name. The murderer of five may have given Professor Marsh more than he bargained for.

On January 29th 1974, April 24th 1978 and October 27th 1987, the Zodiac signed himself "Yours truley" or "Yours truly" as an added signature. "Yours Truly" simply means "Me". Both were used in the Exorcist letter on January 29th 1974. "Yours truly" originated as a formal sign-off for a letter, a shorter version of phrases like "I am truly yours". Today, it is mostly used in a conversational or informal context to refer to oneself in a playful, humorous, or self-deprecating manner. I believe that when the Zodiac Killer mailed the April 20th 1970 letter and Z13 code, he gave us the answer of "My name is....Me" as a playful joke. He was taking the piss.

A solution created by converting ciphertext into plaintext from just 13 characters could never be verified, which is probably why he employed a different technique, inspired by the writings of Poe in Graham's Magazine in 1841. Those three circled 8's may have stood out for a reason. 
 
FOLLOW UP ARTICLE: THE SAME IDENTITY IN THE HALLOWEEN CARD 
FURTHER READING: AN IDENTITY DISCLOSED IN TWO LETTERS 

If the Zodiac Killer was the abductor and murderer of Donna Lass from the Sahara Tahoe Hotel on September 6th 1970, then one might have expected him to claim or insinuate her murder in his next communication, the 13-Hole postcard. Despite later suggesting his involvement in her murder on March 22nd 1971 when the Pines card was mailed, he never increased his victim count from the July 26th 1970 "Little List" letter to the 13-Hole postcard on October 5th 1970 by the Zodiac Killer, which spanned her abduction. Or did he increase the victim count and we simply didn't recognise it? The Pines postcard and 13-Hole postcard both contained punch-holes (suggestive of victims), both contained pasted text, and both carried inverted wording within the postcard. The inverted phrase of "around in the snow" on March 22nd 1971 was clearly referring to the murder and burial location of Donna Lass, so where was the reference to Donna Lass in the inverted text on October 5th 1970?

The construction of the October 5th 1970 postcard may have began just over two weeks after the disappearance of Donna Lass, because all the newspaper cuttings identified on the postcard were sourced from the Oakland Tribune, San Francisco Chronicle and San Francisco Examiner (all separated by only 9 miles)  The cuttings were taken from publications dated September 23rd and 25th. 

On the day the 13-Hole postcard was mailed, a newspaper article by The Orlando Sentinel carried the headline "Zodiac, Killer Of 5 or 13, Silent As Police Wait". The 13-Hole postcard carried a cutting of the number 13 and used the word "police" in the inverted text - so was this section of text giving us a clue to the total victims killed, which now included Donna Lass? The text read "There are reports city police pig cops are closeing in on me. Fk I'm crackproof. What is the price tag now?" Could this have been cryptic in nature, just like the Pines card mailed 5 1/2 months later, telling us surreptitiously that he was the murderer of Donna Lass and reading "There are reports city police pig cops are closeing in on me. Fourteen killed I'm crackproof. What is the price tag now?" In other words, responding to The Orlando Sentinel headline of "Zodiac, Killer Of 5 or 13" on October 5th 1970 (or earlier newspaper that carried the same or similar question).  

​It would mean that the main body of the postcard was reiterating the victim count from the Little List letter on July 26th 1970, but teasing us with the cryptic clue of "Fk" to suggest that there were now "Fourteen killied" in total. This may have been repeated when the Halloween card arrived 22 days later, on October 27th 1970, when he added 13 "floating eyes" to the card, but added the number "14" on the hand of the first skeleton, placed "4-TEEN" atop of the second skeleton, and used the letter "F" once again in the strange symbol at the foot of the card (and on the envelope). The "F" in "Fk" on the 13-Hole postcard may have denoted the number fourteen. The "F" in the strange symbol on the Halloween card may have also denoted fourteen, by combining "Z" and "F" to give us "Zodiac Fourteen". The four dots giving us a clue that "F" meant fourteen. This would mean that the Zodiac Killer gave us two cryptic clues containing the letter "F" in a span of 22 days. The Zodiac Killer could also have added the 14th punch-hole of his career to the Pines postcard, to make up for the one he deliberately withheld from the 13-Hole postcard on October 5th 1970. A postcard in which he decided to use "Fk" instead. But did the Zodiac Killer specifically invert his text in two postcards to represent one victim? That of Donna Lass.

On October 12th 1970, the San Francisco Chronicle released an article entitled Gilbert and Sullivan Clue to Zodiac, featuring the recently mailed 13-Hole postcard with a PM postmark on October 5th 1970. It also brought to our attention the withheld Little List letter mailed on July 26th 1970, stating "Zodiac is still at large today. And he is now claiming he has murdered 13 persons". This was referring to Zodiac's claim in the Little List letter in which he threatened "Being that you will not wear some nice buttons, how about wearing some nasty buttons. Or any kind of buttons that you can think up. If you do not wear any type of buttons, I shall (on top of everything else) torture all 13 of my slaves that I have waiting for me in Paradice". However, this information of a withheld letter and 13 kills was reported by Reuters and published in newspapers such as the Orlando Sentinel on October 5th 1970, the day the 13-Hole postcard was postmarked. Therefore, as Jarett Kobek pointed out to me, this information was probably available the day before the postcard was mailed (on October 4th 1970).

The Orlando Sentinel carried the headline "Zodiac, Killer Of 5 or 13, Silent As Police Wait". This was the headline the same day the Bay Area murderer mailed a postcard with the pasted newspaper text of "Zodiac" and "13", with a reference to "police" in the inverted text (present in the accompanying story). After 71 days of silence from the Zodiac Killer, he featured the prominent number "13" within his postcard and mimicked the headline from the Orlando Sentinel newspaper (or another derived from Reuters) within a 24-hour period. The newspaper asked the question 5 or 13? The Zodiac may have replied with "13" almost immediately. Although the Zodiac Killer sourced his pasted text from several newspaper articles in September, it appears the postcard may have been designed and created as late as the 4th or 5th October 1970. However, the Zodiac Killer chose to use multiple cut-out letters to create the pseudonym "Zodiac" on the 13-Hole postcard, when he had the identical font spelling "Zodiac" in the headline of the newspaper article. This could indicate the inspiration for the postcard lay within another newspaper publication carrying a different headline, but similar messaging regarding the questioned victim total.  

Did the Zodiac Killer have a collection of old newspapers, or did he work as as news vendor or newsagent, giving him ready access to dated material from across the USA? 

Thanks to author Jarett Kobek for his assistance in this matter, who also supplied the newspaper cutting used in this article. 

Many years ago, Zodiac researchers on Mike Morford's forum unearthed some of the likely sources for the pasted newspaper cuttings on the 13-Hole postcard. Recently Jibberjabber, who once contributed to the Zodiac Tapatalk forum. has been thoroughly trawling the newspapers.com website - and by using keywords related to the remaining snippets of text found on this communication, he has unearthed some fresh information that shows the Zodiac Killer was likely preparing this postcard as early as September 25th 1970 (unless he maintained a stockpile of old newspapers for this very purpose). It has been shown previously on this website that some of the wording pasted on the 13-Hole postcard was an update to his Little List letter mailed on July 26th 1970, which was unreleased to the public at the time the 13-Hole postcard was mailed on October 5th 1970. This strongly indicated that the 13-Hole postcard was a genuine Zodiac communication not claiming the disappearance (and possible murder) of Donna Lass from a South Lake Tahoe casino on September 6th 1970.

Vasa Croe found a significant piece of text from the Smidgens comic strip, reading "The pace isn't any slower! In fact it's just one big sprawling subdivided rat race". The particular example below (found by David Oranchak) is from the Oakland Tribune on September 25th 1970. The Zodiac Killer took eleven consecutive words from this comic strip.

From the San Francisco Examiner on the same date (September 25th 1970), Brubaker then discovered the source of the wording "Some of Them Fought" and "It Was Horrible", contained exclusively in two subheadings in another column entitled "The Wounded Lie in the Hallways". 

Jibberjabber then emailed me a further source from the Oakland Tribune on September 25th 1970, containing "You'll hate me" and "but I've got to tell you" in the same line of text. This shows beyond any reasonable doubt that the Zodiac Killer was predominantly searching newspapers from one date in the calendar, securing "The pace isn't any slower! In fact it's just one big", "Some of Them Fought", "It Was Horrible", "You'll hate me" and "but I've got to tell you" to paste onto his 13-Hole postcard. 

Sent to me by Jibberjabber, the word "thirteenth" was also likely sourced from the Oakland Tribune on September 25th 1970 in an article entitled "Our Failing National Health".

Every pasted (complete) word in the message that isn't inverted can now be accounted for in the 13-Hole postcard, sourced from September 25th 1970 and mailed on October 5th 1970 in the form of a postcard. As of this moment, Jibberjabber is trying to identify the source for the remaining inverted text on the communication. The amount of effort displayed in trawling these newspapers to find the desired text, to not only continue the theme of the publicly unreleased Little List letter, but to deliver a specific message, strongly suggests that this correspondence was not prepared by an idle hoaxer.

THE "PACE" POSTCARD AUTHENTIC 

​Thanks to Jibberjabber for his diligent work in this matter. Cragle, another contributor to the Tapatalk forum, has previously found the same and similar newspaper cuttings related to the 13-Hole postcard. I appreciate their efforts to establish a greater understanding of the Zodiac Killer.

UPDATE: Jarett Kobek, author of How to Find Zodiac, has previously unearthed "THERE ARE REPORTS" from the beginning of the upside-down text on the postcard. It was sourced from the San Francisco Chronicle on September 23rd 1970.

After his displeasure that the citizens of San Francisco would not wear "some nice buttons", the List Letter on July 26th 1970 continued with a future tense narrative from The Mikado's As Some Day it May Happen, proclaiming how the Zodiac Killer was set to torture his slaves in paradise, by stating "some I shall tie over ant hills and watch them scream and twich and sqwirm". Despite the Little List letter being unreleased to the public on October 5th 1970, the 13-Hole postcard continued the narrative, now proclaiming in the past tense he had effectively succeeded in torturing his slaves, claiming "Some of them fought it was horrible". It can be argued that this goes a long way to authenticating the 13-Hole postcard as a Zodiac communication. This communication, mailed on October 5th 1970, was followed by another pasted postcard from Berkeley, California on October 17th 1970, which also used cuttings to convey the message, and threatened "Adams You Are Next Zodiac".  It was addressed to Dr. Edward C. Adams, who resided at 102 Camino Don Miguel, Orinda, California. It appears that this postcard was mailed by the same individual as the 13-Hole postcard, but with the October 5th 1970 communication having already been published in the newspapers, we cannot be sure this latest postcard was not created by a copycat. An examination of the adhesive used on both communications would be highly beneficial in determining joint authorship. This determination could be crucial, because if we can prove both were authored by the Zodiac Killer, we may be able to physically place the Zodiac Killer in San Bernardino, alongside Riverside,  in 1969. We could place the Zodiac Killer mailing a letter just 19 miles from the murder site of Cheri Jo Bates.

A letter postmarked Montclair, California on November 10th 1969 and addressed to an individual in Clarinda, Iowa, carried the message "Mr. (redacted) Your Next. The Zodiac". This format was nearly identical to the Edward C. Adams postcard, again using cuttings from a newspaper or magazine. The Montclair mailing was also sent during the hub of Zodiac activity. No communications had apparently been mailed by the Zodiac Killer since the October 13th 1969 Paul Stine letter, but this inactivity was broken by the November 8th 1969 and November 9th 1969 Dripping Pen card and Bus Bomb letter, shortly followed by the Montclair mailing on November 10th 1969 from San Bernardino. If the Adams postcard was the Zodiac Killer, then how high a probability do we place on the Montclair mailing being from the Zodiac Killer, bearing in mind this was addressed to another male individual, with a near identical message, using cuttings from a publication - and more crucially - not released into the public domain when the Edward C. Adams postcard was mailed nearly one year later. If the Montclair mailing was Zodiac, we can place him extremely close to Riverside three years after the Cheri Jo Bates murder. A murder that hadn't been publicly linked to the Zodiac Killer on November 10th 1969.    

Another fascinating aspect of the Montclair, San Bernardino mailing, was that it was fashioned using school notebook paper, just like the three Bates' letters mailed in Riverside on April 30th 1967, later claimed to have been authored by an individual from San Bernardino in 2016. These too, contained an extremely succinct message. If we can link the Montclair mailing to the Adams postcard, and therefore the 13-Hole postcard, we can almost certainly place the Zodiac Killer mailing a letter close to Riverside in November 1969, placing new emphasis on the three Bates letters mailed in April 1967, and shedding further doubt on the lacklustre claims of the individual in 2016. Unless of course, he is the Zodiac Killer. which I seriously doubt as a viable option. A Freedom of Information (FOIA) request for an unredacted version of the below FBI file may unearth the identity of the individual in Clarinda, Iowa, and uncover any commonalities between him and Edward C. Adams. If this individual was a certified psychiatrist, just like Dr. Adams, it could be an extremely interesting avenue of research. And placing the Zodiac Killer mailing a letter close to Riverside at the beginning of his campaign of terror in the Bay Area, could shed a whole new light on the murder of Cheri Jo Bates in 1966 and the communications associated with the case.  

Just over two weeks before the 340 cipher was mailed, Dr. D.C.B. Marsh of the American Cryptogram Association laid down a challenge to the Zodiac in the newspapers to reveal his name in a cipher, however complicated. The wording in the San Francisco Examiner on October 22nd 1969 invoked the name of Edgar Allan Poe, so possibly the designers of the article were hoping that the Zodiac Killer would invoke Edgar Allan Poe to give us his name, making any offering easier to crack. This appeared to influence the Zodiac Killer, because the first cipher mentioned in Poe's essay A Few Words on Secret Writing actually works in decoding the message in the 340 cipher. The second cipher technique in Poe's essay A Few Words on Secret Writing split the alphabet into two portions of 13 letters, so it was surprising that the Zodiac Killer's next code reduced dramatically to 13 characters just like Poe's design (beginning with A and ending with M). See here for essay.

Three years ago, it was suggested that the Zodiac Killer wouldn't again shy away from the challenge of giving us his name, having possibly given us it in an abbreviated format. That is why the cryptic reference of Fk, I'm crackproof caught my eye in the October 5th 1970 communication with 13 punch-holes in the fabric of the card. The punch-holes were separated into a 10 to 3 configuration, positioned in such a way that they mirrored the design of the 13-Symbol cipher. The only way to break the small code was to discover the entry point, and the three circled 8's seemed as good a place as any, especially when we consider Fk, I'm crackproof is split into three parts and fits around the existing K and M in the code. The crosshairs, anchor and Celtic Cross in the code are all religious symbols, with the number 8 representing rebirth, regeneration and a new beginning in Christianity. The figure 888 is also representative of Jesus Christ in Christian numerology. It was discovered that the first 8 began FK, the second 8 began IM and the third 8 began CRACKPROOF, which completed the circle of eternal life. The introduction to the April 20th 1970 letter was also completed, to "This is the Zodiac speaking. By the way have you cracked the last cipher I sent you? My name is Fk, I'm crackproof",

Anyway, this is to show that the Fk, I'm crackproof solution was found before the 340 cipher was cracked by Dave Oranchak, Sam Blake and Jarl Van Eycke on December 3rd 2020, along with its scytale links to Edgar Allan Poe's A Few Words on Secret Writing. This is extremely important when we consider the following. Edgar Allan Poe highlighted certain encipherment techniques in the essay regarding a split alphabet, which are outlined here: and, so placed, a might stand for n and n for a, o for b and b for o, &c. &c. This, again, having an air of regularity which might be fathomed, the key alphabet might be constructed absolutely at random. The next line was: Thus A might stand for P.

These examples can be summarized as;
[1] a might stand for n and n for a
[2] Therefore, r might stand for e and e for r
[3] Thus, a might stand for p (and vice-versa)
Using only these examples in the 13-Symbol cipher, I inserted the possibilities into the code, using the letters K and M as entry points, based on the aforementioned reasoning. The letters N, A and M (not boxed in blue) I have no explanation for. So the search goes on to discover whether the Zodiac applied something else to the encryption. Or whether a different technique was used entirely.

When you take into consideration that the Fk, I'm crackproof solution was suggested in 2017, before the scytale link of the 340 cipher to Edgar Allan Poe, coupled with the formation above using just Poe's examples shown in [1], [2] and [3], it shows a pattern receptive to the remaining letters in the solution. But the three remaining ciphertext characters would need explaining. 

The next encipherment technique described in A Few Words on Secret Writing were the two concentric circles (one fixed), where the outer wheel can be rotated around the inner wheel during the coding process. Here is a working cipher wheel.

On October 22nd 1969, Dr. D.C.B Marsh in alliance with investigators and the San Francisco Examiner, attempted to refocus the Zodiac Killer's attention toward creating a second major cryptogram and "reveal his name in the cipher to established cryptogram experts". Marsh would continue to press the killer throughout the article, stating "I invite Zodiac to send to The American Cryptogram Association a cipher code - however complicated - which will truly and honestly include his name". However, in order to crack any cipher the killer may send, it would have been wise to place certain triggers within the article to guide the Zodiac Killer into choosing a particular cryptographic technique. This may have been the purpose of dropping the name Edgar Allan Poe into the San Francisco Examiner article, thereby influencing the killer to choose a cryptographic technique highlighted by Poe in one of his essays. If the Zodiac Killer then responds with a second cipher, your first port of call would obviously be Edgar Allan Poe.

Although Dave Oranchak doesn't believe the Zodiac Killer used the scytale method of encryption in the recently decoded 340 cipher, this decryption tool does actually decode the message in the 340 cipher. If the Zodiac Killer responded to the prompt by Dr. Marsh and read Edgar Allan Poe's essay A Few Words on Secret Writing, he would have noticed that the first topic of discussion was the scytale cipher, which involves disguising a message by separation, avoiding the common left-to-right method of decryption. This is what the Zodiac Killer used in his 340 cipher. In further reading of A Few Words on Secret Writing, it became apparent that other encryption methods were discussed in addition to the scytale method, with the possibility existing that the Zodiac Killer may have adopted one of these techniques for his following 13-Symbol cipher on April 20th 1970. The most notable encryption methods discussed included separating the alphabet A to M, and N to Z, into two equal parts of 13 letters. This involved placing the alphabet into the following configuration.

Here is an excerpt from Edgar Allan Poe's A Few Words on Secret Writing: and, so placed, a might stand for n and n for a, o for b and b for o, &c. &c. This, again, having an air of regularity which might be fathomed, the key alphabet might be constructed absolutely at random. The next line was: Thus A might stand for P.

If we then represent the second ciphertext character N (11th position} with the plaintext character A shown in Poe's writing, we get the diagram shown below, with the circular Fk, I'm crackproof starting to emerge.

The relationship  between the remaining ciphertext characters of N, A and M, to the plaintext characters in the solution of O, C and K respectively, can be seen in the diagram below. These are never more than two apart in the alphabet. This is a work in progress.

After two Zodiac attacks in close succession on September 27th 1969 and October 11th 1969, investigators must have feared an escalation in terror from the Bay Area murderer, so it would have certainly been in their interests to switch the Zodiac Killer's attention to communication instead of murder. On October 22nd 1969, Dr. D.C.B Marsh in alliance with investigators and the San Francisco Examiner, attempted to refocus the Zodiac Killer's attention toward creating a second major cryptogram and "reveal his name in the cipher to established cryptogram experts". Marsh would continue to press the killer throughout the article, stating "I invite Zodiac to send to The American Cryptogram Association a cipher code - however complicated - which will truly and honestly include his name". However, in order to crack any cipher the killer may send, it would have been wise to place certain triggers within the article to guide the Zodiac Killer into choosing a particular cryptographic technique. This may have been the purpose of dropping the name Edgar Allan Poe into the San Francisco Examiner article, thereby influencing the killer to choose a cryptographic technique highlighted by Poe in one of his essays. If the Zodiac Killer then responds with a second cipher, your first port of call would obviously be Edgar Allan Poe.

Although Dave Oranchak doesn't believe the Zodiac Killer used the scytale method of encryption in the recently decoded 340 cipher, this decryption tool does actually decode the message in the 340 cipher. If the Zodiac Killer responded to the prompt by Dr. Marsh and read Edgar Allan Poe's essay A Few Words on Secret Writing, he would have noticed that the first topic of discussion was the scytale cipher, which involves disguising a message by separation, avoiding the common left-to-right method of decryption. This is what the Zodiac Killer used in his 340 cipher. In further reading of A Few Words on Secret Writing, it became apparent that other encryption methods were discussed in addition to the scytale method, with the possibility existing that the Zodiac Killer may have adopted one of these techniques for his following 13-Symbol cipher on April 20th 1970. The most notable encryption methods discussed included separating the alphabet A to M, and N to Z, into two equal parts of 13 letters. Followed by a technique involving two concentric discs, akin to the Union Cipher Disk that held the number configurations of 000 and 888. These techniques show promise when we consider the design and structure of the 13-Symbol cipher. This has been covered in a much more extensive article, so it will not be covered any further here.  

Dr. Marsh, under the banner of Cipher Expert Dares Zodiac to Tell Name, would persist throughout the article into cajoling the Zodiac Killer to reveal his name by way of a cryptogram. This is why another passage in A Few Words on Secret Writing caught my attention - and may have resonated with the Zodiac Killer too. It concerned a reader sending in cryptograms to Edgar Allan Poe, but refraining from giving his name. The passage read "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".

This reminded me of the statement by Dr. Marsh when he challenged Zodiac, who he contended "had not told the truth in his cipher messages to the Examiner, the Chronicle and the Vallejo Times-Herald". He claimed "Zodiac has not done this, because to tell the complete truth in relation to his name would lead to his capture". Did the Zodiac Killer read this passage in A Few Words on Secret Writing and get some ideas?

The reader who mailed Edgar Allan Poe from Stonington, Connecticut, failed to supply his name, but did begin by placing a letter S, followed by a horizontal dash, similar to the Zodiac Killer's introduction on April 20th 1970, The Zodiac Killer began the introduction to his 13-Symbol cipher by stating MY NAME IS ---------. The sender of the cryptograms to Poe only signed his name at the bottom of the intoductory letter by use of initials, concluding with "I am yours, respectfully S.D.L." Not wanting to shy away from the challenge of Dr. Marsh a second time, I couldn't help thinking that the Zodiac Killer may have rose to the challenge and given us the initials to his name (or fictitious initials), just like the sender of the cryptograms from Stonington, Connecticut. Another thing to note, is that Dr. Marsh laid down this challenge on October 22nd 1969, so 182 days had elapsed before the Zodiac Killer's third confirmed cryptogram arrived at the San Francisco Chronicle on April 21st 1970.

Paul Avery wrote on April 22nd 1970, in an article entitled Zodiac Sends New Letter-Claims Ten, that "the killer who calls himself Zodiac has once again written to the Chronicle. In a letter received yesterday, Zodiac claims he has killed again". This letter was received by the San Francisco Chronicle on April 21st 1970, the exact day and month the letter from Stonington, Connecticut was postmarked from the anonymous sender to Edgar Allan Poe. This all may have been coincidence, but it would certainly be worth looking for the Zodiac Killer's initials as part of the answer to the 13-Symbol cipher.

That answer could be "This is the Zodiac speaking. By the way have you cracked the last cipher I sent you? My name is Fk, I'm crackproof", given to us in the Zodiac Killer's postcard five-and-a-half months later as a big hint to its decipherment. The 340 character cipher was split into rows of 9, 9 and 2 sections. The 13-Symbol cipher may have been split into 2. 2 and 9 sections, with the circled 8's beginning each section of the phrase. The letters K and M were already in place for a perfectly circular message, as highlighted in the October 5th 1970 communication by the Zodiac Killer, in which he supplied us with the phrase Fk I'm crackproof.   

On April 20th 1970, the Zodiac Killer mailed a 13-Symbol cipher to the San Francisco Chronicle, in addition to a bus bomb diagram threatening to blow up a school bus. Let's compare the 13-Symbol cipher to the 13-Hole postcard on October 5th 1970, in which the Zodiac Killer may have completed the introduction of "My name is" to "My name is Fk, I'm crackproof", again teasing us with a less than complete resolution to his real identity.

In a previous article entitled The Dick Tracy 340 Cipher we explored the idea that the "13 punch-holes" and "red crucifix decoder" of the October 5th 1970 communication, may have been giving us a clue into the "Paradice and Slaves" formation within the 340 cipher. While this may remain the case, there could be a more direct link between the 13-Hole postcard and the April 20th 1970 13-Symbol cipher (and a case of dual functionality). There is the obvious link of 13 characters in the April 20th 1970 code and the 13 punched holes, but there is also the common link of phraseology in "What is the price tag now" and "I am mildly cerous as to how much money you have on my head now". These were the only two times the Zodiac Killer asked about the bounty on his capture. There is also a link between both configurations. The 13-Symbol cipher had three circled number 8's positioned in the center of the code (with 4 characters either side and two between them). The 13-Hole postcard had three distinct punch-holes in the center of the formation (with 4 punch-holes either side and two between them).

When you look at the 13-Hole postcard it is clear that the Zodiac Killer had plenty of room to configure the punch-holes into any arrangement he liked, yet he chose to overload one line with ten holes, with just three on the other. One could be forgiven for believing there was purpose in this design. 

The April 20th 1970 and October 5th 1970 communications were littered with Christian symbolism. We have the Red Crucifix, the three 8's (which in Christian numerology represents Jesus, or Christ the Redeemer), the Celtic Cross and the Anchor (adopted by Christians as a symbol of hope in future existence). The number 8 (infinity) in Christianity is representative of eternal life, rebirth, regeneration or a new beginning. They all play into the belief of an afterlife. This brought forward the notion that the number 8 in the 13-Symbol cipher was the beginning of each element of the phrase "Fk, I'm crackproof" (as shown above in green). In the diagram above, one can see that the letter F becomes the 5th letter in both sequences, the letter I becomes the 7th letter in both sequences, and the letter C becomes the 9th letter in both sequences, with the K and M slotting in between. In short, the letters FIC in both instances are separated into three circles, positioned identically in both sequences. The use of circles in both the 13-Hole postcard and 13-Symbol cipher plays directly into the phrase "Fk I'm crackproof", which when placed around the already existing K and M in the code, forms an eternal and circular repeating sequence. The April 20th 1970 communication now satisfied the October 22nd 1969 challenge by cryptographer D.C.B. Marsh in the San Francisco Examiner, for the Zodiac Killer to reveal his name. The letter now read "This is the Zodiac speaking. By the way have you cracked the last cipher I sent you. My name is Fk, I'm crackproof".                

Without any additional information the April 20th 1970 code is unsolvable. The Zodiac Killer was many things, but he wasn't a  half-witted imbecile with the brain of a gibbering lunatic when he designed this short 13 character code. In a newspaper article authored by Will Stevens on October 22nd 1969 in the San Francisco Examiner, Dr. D.C.B. Marsh challenged the Zodiac Killer no less than four times to supply us with his name in a cipher. Dr. Marsh stated in one section "The killer wouldn't dare...as he claimed in letters to the newspapers...to reveal his name in a cipher to established cryptogram experts". He added: "I invite Zodiac to send The American Cryptogram Association, care of Dr. D.C.B. Marsh, a cipher code - however complicated - which will truly and honestly include his name", quoting Edgar Allan Poe "that any cipher devised by man can be solved by man". Therefore, it was no great surprise when Zodiac's April 20th 1970 letter landed on the desk of the San Francisco Chronicle with the contemptuous opening line of "By the way have you cracked the last cipher I sent you? My name is------".  He knew his last cipher had not been solved, yet in mocking fashion was replying to the claim "that any cipher devised by man can be solved by man". The phrase "by the way" is used to introduce a new subject to be considered or to give further information. The Zodiac was effectively saying to Dr. Marsh he was wrong, now try this new cipher for size.

The Zodiac Killer chose to include eight characters from the English alphabet in his cipher, with 26 to choose from. Bearing in mind the challenge by Dr. Marsh was for Zodiac to reveal his name in the cipher, what are the odds of "NAM" forming consecutively, along with seven of the eight letters chosen from the alphabet being present in the word "name", being unintentional? Thereby leaving only K surplus to requirements. Although not impossible that this was just coincidental, one could argue that the N, A, M and E were chosen deliberately, considering the challenge by Dr. Marsh and the mocking introduction to the cipher by the Zodiac Killer. Did the Bay Area murderer, responding to the proposition of the eminent cryptographic expert to supply his "true identity" and "name", include his "identity" on line 20 of the 340 cipher, and use the word "name" in the Z13 just five months later?

Was the Zodiac Killer was just playing games with The American Cryptogram Association, determined not to have a further two ciphers cracked in a matter of days? - and thereby avoiding the acute embarrassment of creating "a cipher designed by man that can be solved by man". After the challenge on October 22nd 1969, the Zodiac Killer was going to design the remaining ciphers on his terms, to which he would ultimately reveal the answers. He wasn't going to allow Dr. Marsh the satisfaction of using cryptographic techniques to pry open his ciphers, so used the wording of Dr. Marsh "to send a cipher code, however complicated" against him, by sending two of the most infantile ciphers possible.

If we strike out the seven letters that have now formed "NAME" we are left with "NAME K". If this was the beginning letter of his surname, then the first circled 8 could represent his forename. So, if we are looking for an expanded declaration of his name using both forename and surname in later communications, we would be looking for a two letter combination, ending in K. But in addition, this would have to be accompanied by some pertinent text alongside the two letter declaration. This occurs in only one subsequent communication of the Zodiac Killer.   

You will notice how he begins this section of text, with "There are reports city police pig cops are closeing in on me". The text refers to the notion that law enforcement could possibly be close to capturing him, with the last word of "me" followed by a comma. One would therefore expect the next line to be a reaction by him in relation to this news. This has long been thought to be the abbreviated word "fuck" - an approach he didn't take in the August 4th 1969 Debut of Zodiac letter, when he wrote "When I hung the phone up, the damn X@ thing began to ring & that drew his attention to me + my car". The two letters of Fk may very well have been his initials - and a declaration that he "Fk, was crackproof". It may also be the answer to the 13 Symbol cipher, when responding to the challenge of Dr. Marsh.

If "Fk, I'm crackproof" was the answer to the 13 Symbol cipher, then one would have expected the Zodiac Killer to have designed the cipher with some markers present, that the answer could be fitted around later. Especially if no cryptographic technique was required. The phrase of "Fk, I'm crackproof" was the perfect response to Dr. Marsh, in that Zodiac could satisfy the request of Dr. Marsh by giving us his name, albeit in the shortened format. He began the April 20th 1970 letter by stating "By the way have you cracked the last cipher I sent you? My name is------". He responded immediately with his name (FK), before rubbing Dr. Marsh's "noze in his booboos" by declaring he was crackproof, having also just taunted the cryptographic expert with the mocking introduction of "have you cracked the last cipher I sent you?". The Zodiac Killer knew that Dr. Marsh would never solve his Z340 and Z13 ciphers when he designed them, because they couldn't be solved using standard cryptographic methods - and more importantly - the answers were 6 months in the making.

The circled eights (The number 8 in the Bible represents a new beginning) seemed to have extra significance compared to the other characters in the cipher. Because the Celtic Cross and Anchor have relevance in Christianity, it was considered that the number 8 was the beginning of each word. The three circled eights, along with the K and M inside them, were the markers I described earlier, so that his later solution would be understood. All we had to do now, was place the phrase "Fk I'm crackproof" into the 13 Symbol cipher, with each number 8 beginning each element of the phrase.

The completed introduction to the April 20th 1970 letter now read perfectly with respect to the Zodiac Killer giving us his name: "This is the Zodiac speaking. By the way have you cracked the last cipher I sent you? My name is Fk, I'm crackproof". And so did the phrase "There are reports city police pig cops are closeing in on me, Fk I'm crackproof". Placing his real name in the 13 Symbol cipher was never a realistic proposition - and even if this had been done - it would never have been revealed and could never be proven. The only way a solution to the 13 Symbol cipher could be proven beyond any doubt, was for the Zodiac Killer to give us the answer. He obliged on October 5th 1970, as he did for the Z32 on July 26th 1970 and the Z340 on October 27th 1970. Proving this is the answer to the Z13 in isolation, is nigh on impossible, but when all three ciphers can be answered in three consecutive communications using only the words of Zodiac, it exposes a killer unable to resist temptation. The Zodiac Killer simply didn't have the temperament to take his secrets to the grave.