The American Greetings card or Eureka card was believed to have been mailed by the Zodiac Killer in December 1990, depicting a wintry scene of a snowman and rabbit on its exterior, with an accompanying prewritten message of "FROM YOUR SECRET PAL CAN'T GUESS WHO I AM YET? WELL, LOOK INSIDE AND YOU'LL FIND OUT...". Once opened it revealed the prewritten reply of "...THAT I'M GONNA KEEP YOU GUESSIN'! HAPPY HOLIDAYS, ANYWAY". No additional writing from the sender was found on the card inner.

Many Zodiac Killer enthusiasts have questioned over the last sixteen years whether the imagery on the original American Greetings card was altered by the sender of the communication. These individuals have considered that the Zodiac Killer may have manipulated the snowman to look like Groucho Marx, because he was cast as Ko-Ko in The Mikado, reciting both A More Humane Mikado and  As Some Day it May Happen, two Gilbert & Sullivan acts used by the Zodiac Killer in his Little List letter mailed on July 26th 1970.

The designer of the card was George Schill, a contract artist with the American Greetings Card Company (Corporation) for 38 years, who informed me that all the imagery on the card (including the snowman) is exactly as he created it. In other words, nothing was added to the card outer by the Zodiac Killer. George, who retired several years ago, remarked "I did create the card as shown" and that "The ‘“guess who“ copy is typical of a greeting card friendship/secret admirer type of card, and I added the Groucho Marx glasses which are cliche". George's website lists his accomplishments as an illustrator, stating "my work has garnered a number of awards and has been selected for inclusion in the NY Society of Illustrators Annuals, Communication Arts, Printʼs Regional Design Annuals, and the Addyʼs. In addition to my freelance work, I have designed thousands of greeting cards as a contract artist with the humor divisions at American Greetings, where I also write gags, develop characters, and concept new lines. Several of my cards have been nominated for the National Cartoonist Society Reuben Award".

I would like to thank George for supplying me with this information and clearing up some of the outstanding questions regarding the design of the Eureka card. You can visit George's website at https://www.georgeschill.com/   

It has been stated that one of the keys depicted in the Eureka card mailed in December 1990 was traced to its once owner, Chester Clark Klingel. The question that has arisen is: if the Eureka card was mailed by the Zodiac Killer, how did he acquire the post office box key of Chester Clark Klingel in order to photocopy it? If the Zodiac Killer didn't find the key and trace its owner, then the logical conclusion is that at some point he may have crossed paths with Chester Clark Klingel. After Chester married his wife, Blandina, in 1965, they visited relatives regularly in Turlock, before they purchased property at 6413 E Keyes Road in Hughson, California in 1973 (now Alpine Pacific Nut Company). They eventually sold this property and bought a 20-acre ranch from walnut huller, Glenn DeLay in 1976. This is the only tenuous link that can be forged between Chester Clark Klingel and the Zodiac Killer, who, if we believe abducted Kathleen Johns on March 22nd 1970, may have been traveling back to Vallejo from the Turlock or Hughson area that night. Additional link.

​Although the Kathleen Johns abduction occurred three years before the Klingels purchased the property in E Keyes Road and six years before the second purchase, the Zodiac Killer could have had family or friends, or had business dealings in Turlock or Hughson, that required him traveling there from the Bay Area before and after the Kathleen Johns abduction. If he had visited this area of California in 1970, he could have visited it regularly pre and post March 22nd 1970 - possibly into the 1980s and 1990s, where he may have crossed paths with Chester Clark Klingel in a personal or professional capacity. The route that Kathleen Johns took on March 22nd 1970 had her traveling northwest on Highway 99, through Turlock and near Hughson, California, before reaching Modesto and heading west on Highway 132. In fact, E Keyes Road passed over the top of Highway 99, with the 15-acre farm at 6413 E Keyes Road in Hughson situated less than two miles from Highway 99.

If the Zodiac Killer was responsible for the Kathleen Johns abduction in 1970, and had lived in the Bay Area during this period, it's very unlikely he would have taken a 170-mile round trip to an isolated stretch of road just to commit this type of crime, that he could have committed anywhere. This opens up the possibility he may have had reason to be in Turlock or Hughson pre and post 1970 (possibly business related). However slim, is there a chance that the Zodiac Killer trailed Kathleen Johns from Highway 99 somewhere in the region of Turlock or Hughson, or could he have traveled from this area and randomly come across Kathleen Johns as they both drove along Highway 132 at approximately 11:15pm?. Any continuing journeys to the Turlock region subsequent to the night of March 22nd 1970 may have facilitated the opportunity for the Zodiac Killer and Chester Clark Klingel to have crossed paths with one another. According to the obituary of Chester Clark Klingel, he remained in Turlock until the death of his wife Blandina on September 9th 1993, when he sold the farm and moved to Eureka. Therefore, it is entirely plausible that the Zodiac Killer 'acquired' and photocopied the post office box key from Chester in the years up to and including 1990, while Chester lived in Turlock, California.

On March 3rd 2007, Daniel King, editorial assistant of the San Francisco Chronicle unearthed the Eureka card among some photo files, just after the release of the 2007 David Fincher film, Zodiac. The correspondence contained a Christmas greetings card with the message "FROM YOUR SECRET PAL CAN'T GUESS WHO I AM YET? WELL, LOOK INSIDE AND YOU'LL FIND OUT..." and once opened it revealed: "...THAT I'M GONNA KEEP YOU GUESSIN'! HAPPY HOLIDAYS, ANYWAY". This message was part of the original card, which had no additional writing from the sender. Within this card the sender had added two photocopied post office keys on a keychain, each of which contained five punched and traceable numbers (79408 and 58851). It was claimed that these post office box keys were traced to their owner, Chester Clark Klingel, who it was stated lived in Eureka in 1990 at the time this communication was mailed to the San Francisco Chronicle in December. 

According to the obituary of Chester Clark Klingel, it somewhat detailed his timeline. The obituary read "Chet's first wife Yolanda passed away in a car accident. His second marriage was short but his third to Blandina Sarkis added love, happiness, family and great food to his life. He had many good years in Tam Valley, CA, before beginning a farming venture near Turlock, CA. Chet and Blandina bought nut orchards and developed a successful walnut hulling and drying business. After Blandina passed away, the farming project lost appeal. Chet sold the farm and moved to Eureka, CA, where he made new friends". The problem we have, is that the obituary stated that Chester Clark Klingel moved to Eureka after Blandina Sarkis Klingel died. She died on September 9th 1993 (aged 63). Therefore, if the obituary is accurate, Chester Clark Klingel moved to Eureka subsequent to her death in September 1993. So what was he doing with a post office box in Eureka when he didn't live there in 1990? Blandina Sarkis Klingel was buried in Turlock Memorial Park, Turlock, Stanislaus County, which is 370 miles from Eureka. 

'The Foreigner', a contributor to the Zodiac Killer Site forum, did point out that Chester Clark Klingel's daughter was living in Eureka at the time the Eureka card was mailed. However, If the claim we have been led to believe for many years is correct, that Chester Clark Klingel had been living in Eureka in 1990 with his wife Blandina, it would be unusual for her to be buried in Turlock, Ca, which is a 740 mile round trip for her husband. This story requires more explanation, because something doesn't make sense.  

The Zodiac Killer had a propensity to tease us with his name, but he also mailed two communications in the form of postcards on March 22nd 1971 and July 13th 1971, where he teased us with the name of the victim he was claiming. The "Sierra Club" of the Pines card overlayed over the Sierra Club of Clair Tappaan Lodge on the northwest side of Lake Tahoe, left the punched hole firmly over the "Donner Memorial" State Park. The Monticello card of July 13th 1971 gave us the phrase "Near Monticello Shought Victims 21 ...... In The Woods Dies April". The card was insinuating the murder of Kathy Bilek in the woods of Villa Montalvo in Saratoga on April 11th 1971. The murder site was near the neighborhood of Monticello in San Jose, where one of Zodiac's previously claimed victims was buried. Kathy Snoozy was buried in the Oak Hill Memorial Park & Cemetery. The two pasted cards were clues to the victims he was claiming, both of which were inferred by the remembrance of a memorial park. The Eureka card mailed in the December of 1990 was likely suggesting a third name. But on this occasion, the Zodiac Killer may have known the living victim (or at least known his name).

First brought to our attention on Tom Voigt's message board, the photocopied keys of the Eureka card were traced by the numbers on them to a post office box and one eventual owner, who they called "Sam", but was later identified as Chester Clark Klingel who lived in Eureka. This is obviously relevant because the Christmas greeting card was postmarked Eureka, California. It has been speculated that the Zodiac Killer may have found the keys, which has some merit when you consider the Ancient Greek word of Eureka meaning "I have found". However, it's unlikely that these keys were just found on the street without the Zodiac Killer knowing the owner's identity, because the Eureka card was designed in such a way that it hinted at the name "Chester" by the contents of the card. He gave us clues to the names of Donna Lass and Kathy Snoozy in two previous cards, so why shouldn't he do it for a third time. Having noticed this possibilty, I was happy to see that somebody else had also touched on this idea on the Zodiac Killer message board, but it was sadly passed over. Nin stated "Another trivia, Chester Carlson, the inventor of xerography (xerox) spent 3 years at RCC, Riverside".   

The Zodiac Killer may have been directing law enforcement to the home of Chester Clark Klingel in Eureka, with the photocopied keys and postmark. The Eureka card has the pre-printed message "From your secret pal, can't guess who I am yet? Well, look inside and you'll find out", challenging us to discover the name inside the card. The only way to discover the name was to identify the numbers on the keys. But why did the Zodiac Killer photocopy the keys? It could have been another clue to the owner of the keys, because as Nin highlighted:

Xerox was founded in 1906 in Rochester, New York, as The Haloid Photographic Company. It manufactured photographic paper and equipment. In 1938, Chester Carlson, a physicist working independently, invented a process for printing images using an electrically charged photoconductor-coated metal plate and dry powder "toner". However, it would take more than 20 years of refinement before the first automated machine to make copies was commercialized, using a document feeder, scanning light, and a rotating drum. Chester Floyd Carlson is best known for inventing electrophotography, the process performed today by millions of photocopiers worldwide. Carlson's process produced a dry copy, as contrasted with the wet copies then produced by the mimeograph process. Carlson's process was renamed xerography, a term that means "dry writing".

How likely is it, that the not so common name of "Chester" would be the inventor of a process used by millions of photocopiers worldwide, and would be the owner of at least one of the photocopied keys placed inside the Eureka card by the Zodiac Killer, while also living in Eureka, California in 1990. The card outer was now completed: "From your secret pal, can't guess who I am yet? Well, look inside and you'll find out". Chester. Chester Clark Klingel was seemingly ruled out as being the Zodiac Killer, so in all probability this was just another game by the Zodiac Killer, intending to misdirect law enforcement on yet another wild goose chase. But if he knew the name of Chester Clark Klingel when designing the greeting card, it may bring us a little closer to finding out who he was.

Recently we covered the January 10th 2001 Happy New Year card, stating it was likely mailed by the same individual as the December 1990 Eureka card, When the individual authored the 2001 card and mailed it to the San Francisco Chronicle, we have to remember that the 1990 Eureka card wasn't made public until 2007. Therefore, he couldn't have been imitating the design of the 1990 Eureka card envelope. There has been over emphasis on comparing the handwriting between the two communications - obviously some believe the handwriting is a good match, while others disagree - and this is par for the course. To determine whether these communications were created by the same author (or the Zodiac Killer), we have to analyze their composition and their layout.

For those who strongly believe the 1990 Eureka card is the Zodiac Killer, this is an important question. If the communications can be linked, then advocates for the 1990 Eureka card must advocate for the 2001 Happy New Year card also. It would rule out any suspects dead or incarcerated subsequent to December 1990 and up to January 10th 2001 such as Theodore Kaczynski, who was arrested on April 3rd 1996 and given eight life sentences. It would also rule out high profile suspect Arthur Leigh Allen who died on August 26th 1992. Now obviously, staunch advocates of Theodore Kaczynski or Arthur Leigh Allen, who also believe that the 1990 Eureka card was Zodiac, will almost certainly reject the 2001 Happy New Year card by default, or now distance themselves from the Eureka card if it was proved it was linked to the 2001 card. Here is a comparison between the envelope handwriting before we move on.

Any hoaxer or copycat who wants to mail an imitation Zodiac letter, particularly in 1990 and 2001, has a wealth of genuine Zodiac communications to draw upon, including the envelopes. The November 16th 1970 Paul Avery newspaper article in the San Francisco Chronicle, was one such example of how to address an envelope in Zodiac fashion. The need to mimic and convince the reader you are the genuine Zodiac, would supersede the requirement of the real Zodiac to convince the reader he is the genuine Zodiac. The real Zodiac doesn't need to convince anybody he is the Zodiac Killer, because he knows he is. One can therefore argue, that a communication in 1990 or 2001 that is pertaining to be from the Zodiac Killer, that looks nothing like the Zodiac Killer, could very well be the Zodiac Killer. The need to mimic old communications is not a requirement for the real killer. So when researchers state that the 2001 Happy New Year card looks nothing like old Zodiac communications, they may very well be negating their own position of rejecting it. Why should the 1990 or 2001 handwriting look like the handwriting from twenty to thirty years ago. Handwriting varies over time and is easily manipulated.

The 1990 Eureka card and 2001 Happy New Year card, whether Zodiac or not, were mailed eleven years apart. We are not aware of any other Zodiac or copycat communications in between these years. If there has been any, they have not been released. We have to look at these two communications in respect to all the confirmed and suspected copycat letters from 1969 to 2001 (a span of 32 years). If these two communications were not the same author (and the 2001 author couldn't have copied the 1990 author), then it is unusual that these latter two communications are both festive greetings cards, never before mailed to the newspapers by the Zodiac Killer or a copycat in the thirty-two years prior. Not withstanding the handwriting, it is also the first time the Zodiac Killer or a copycat had employed the address format of "901 Mission Street" and the numbering "94103". So we have two communications, both are festive cards, and both use an envelope address format never employed in any previously publicized letters from the Zodiac Killer or otherwise. We have to ask the pertinent question of why a copycat would attempt to look nothing like the real killer. He is effectively imitating nothing the Zodiac Killer had done previously.      

Either the Zodiac Killer or somebody purporting to be the Zodiac Killer mailed a Happy New Year card to the San Francisco Chronicle on January 10th 2001, disgusted that San Francisco citizens were "getting murdered" by Muni drivers. The day before, on January 9th 2001, the Examiner ran an article describing how a Muni streetcar struck and killed pedestrian Guang Zhan Ouyang on Sunday, January 7th 2001. Another fatality occurred the following day on Van Ness Avenue. This newspaper article is courtesy of Cragle from Zodiac Killer Site forum - and is undoubtedly the trigger for the January 10th 2001 Happy New Year card. After all, the author opened up with the line [corrected] "Dear Sir. Wherever you are. This is disgusting to read, what seems to be a news that nobody really cares, but the relatives of innocent citizens murdered in our beloved S.F. It's always the pedestrians fault and never those bastard Muni drivers".

The Zodiac Killer was extremely fond of reacting to newspaper articles in his heyday, but what was it about this particular article that triggered such a response, just over eleven years after the December 1990 Eureka card (assuming the Zodiac Killer was responsible for both communications). Cragle pondered the question; Could the line "Noboby really cares but the relatives of innocent citizens MURDER in our beloved SF" allude to a relationship of some sorts to the person quoted in the article?

Here is another Examiner newspaper article, dated January 3rd 2001, describing the death of Brian Edward Cotter (18) as he played the game of "chicken" with a Muni streetcar. Thanks again to Cragle for supplying this cutting.

Here is a communication mailed to the San Francisco Chronicle on January 10th 2001 threatening the Muni drivers of San Francisco, widely believed to be somebody mimicking the Zodiac Killer. While this may be the case, one has to consider the style and format of the writing (particularly on the envelope) with respect to previous Zodiac communications. No other authenticated Zodiac communication prior to this one carried the address of "901 Mission Street" with "San Francisco, CA 94103". Additionally, no previous Zodiac communication (or suspected copycat communication) was ever mailed as a festive greetings card, other than the Eureka card, which is bound to this communication by three unique features. I believe Tom Voigt of Zodiackiller.com considers the Eureka card mailed in 1990 to be a plausible Zodiac correspondence, placing this communication in his "Letters from the Zodiac" section on the message forum.  

The Eureka card is the only other possible Zodiac communication addressed in near identical fashion to the 2001 offering (shown in tandem with the envelope below). The problem arises when we consider that the Eureka card was not discovered until March 3rd 2007 by editorial assistant Daniel King of the San Francisco Chronicle among some photo files. The 2007 Zodiac movie directed by David Fincher and based on the Robert Graysmith book, was released in the USA the day before this correspondence was unearthed, on March 2nd. The movie had its premier in Los Angeles and California on March 1st.

This means that whoever wrote the January 10th 2001 card, addressed it in near identical fashion to a previously unreleased and potential Zodiac communication (thought to be genuine by many). The Eureka card wasn't made public until 2007, so the author of the 2001 communication has a high probability of being the author of the December 1990 Christmas card. You cannot 'copycat' the handwriting or style of an envelope that hasn't been released into the public domain. If you believe the Eureka card to be genuine, it follows that you should lean towards the 2001 communication being genuine also. If you hold the opinion that Zodiac was still alive in 1990 mailing Christmas cards, then it is extremely likely he was still active in 2001 doing exactly the same thing. ​

This is another speculative article searching for the name of the Zodiac Killer within his communications - so caution must be applied to any conclusions that are reached in the following analysis.

After the challenge by Dr. Marsh on October 22nd 1969 requesting that the Zodiac Killer give us his real name in a cipher "however complicated", the notion of a killer hinting at his name in later communications is certainly plausible. Presented in a hidden format, the Zodiac Killer knew that it could never be used as evidence against him, unless the unearthed solution could be proven beyond doubt to be the correct one. In the article Return to Sender we explored the introduction and answer to the 13 symbol cipher of "This is the Zodiac speaking. By the way have you cracked the last cipher I sent you. My name is....Fk, I'm crackproof". The Zodiac Killer effectively giving us his name, but in the shortened format. 

Three months later, the Zodiac Killer mailed the Little List letter on July 26th 1970 paraphrasing the recital of Groucho Marx's As some day it may happen from the Gilbert & Sullivan comedic opera, The Mikado. On October 12th 1970, the San Francisco Chronicle featured this letter under the title of Gilbert and Sullivan Clue to Zodiac, stating "A quiet search for onetime Ko-Ko's has turned up none that could be Zodiac. Obvious differences in physical description and handwriting comparisons have cleared all Ko-Ko's tracked down since the arrival of the July 27 letters". But what if the Zodiac Killer wasn't choosing the character of Ko-Ko because he played him in a production or even liked the theater, but the name Ko-Ko was somehow pertinent to his identity. Bearing in mind the phrase "My name is....Fk, I'm crackproof", could the Zodiac Killer's surname begin with Ko. The phrase "FK, I'm crackproof" is actually 14 letters long, but it was fashioned into a code of only 13 characters. Could this deliberate formatting indicate his initials were FK in a name comprising of 13 letters?

Although questionable Zodiac correspondence, the December 1990 Eureka card yet again featured Groucho Marx in imagery on the front of the card, promising us his name yet again. The card read "From your secret pal, can't guess who I am yet? Well, look inside and you'll find out" - and contained within was a xerox copy of two keys. This too triggered the notion of a surname beginning with K. The Exorcist letter mailed on January 29th 1974 also featured a verse recited by Groucho Marx, but more importantly, the verse of Tit-Willow by Ko-Ko was preceded by the line "Signed, yours truley", implying the character in the verse had something to do with his name. This wasn't all.

We argued that the Zodiac Killer gave us the answers to all his "unsolved" codes in his own words, and the Celebrity Cypher mailed on September 25th 1990 to the Vallejo Times-Herald may have followed a similar pattern. The name of the sender was hidden behind 5 and 8 characters totaling 13, placed on the address side of the postcard and at the foot of the communication. A Celebrity Cypher with a likely introduction of "My name is", exactly like 13 symbol cipher mailed on April 20th 1970. If the initials of the killer were given in that instance within the phrase "Fk, I'm crackproof", then there are reasonable grounds to believe the 5 and 8 letters of the name on the Celebrity Cypher begin with an F and K also. In the Return to Sender article we hypothesized the forename as "Frank", based upon the phrase "how much money you have on my head now" in reference to the stamp on the April 20th 1970 letter - and this fits nicely into the Celebrity Cypher solution. I have speculatively placed "Ko" at the beginning of the surname regarding The Mikado references, but will venture no further. There are possibilities based on the "keys" provided by the Eureka card to suggest his surname could end in "key" or "ki" such as "Kominski", however, there are plenty of other options pertaining to the xeroxed image.

Comparisons can be drawn between the April 20th 1970 and September 25th 1990 communications with respect to a name comprising of 13 letters (split into 5 and 8 characters) - and bearing in mind the Christmas card, likely mailed close to December 25th 1990 continuing the theme of promising us his name - can a link be forged between all three regarding the identity or name of the Zodiac Killer? 

The following will be extremely speculatory and should not to be taken too seriously, but I wanted to examine the prompt by Professor D.C.B. Marsh who told the Examiner on October 22nd 1969: "The killer wouldn't dare, as he claimed in letters to the newspapers, to reveal his name in the cipher to established cryptogram experts. He knows, to quote Edgar Allen Poe, that any cipher created by man can be solved by man. Zodiac has not told the truth in his cipher messages to the Examiner, the Chronicle and the Vallejo Times-Herald. Zodiac has not done this, because to tell the complete truth in relation to his name - in cipher code - would lead to his capture. I invite Zodiac to send The American Cryptogram Association a cipher code - however complicated - which will truly and honestly include his name".

When recently promoting the notion of a killer providing us with all the solutions to his ciphers in Three Months After the Mount Diablo Code, it was considered that the Zodiac Killer did respond to Dr. Marsh, but he certainly wasn't going to be as forthcoming as to provide us with his full name as Dr. Marsh had honestly requested. Hence the idea that he did give us his name, albeit in the abridged version of his initials which he supplied to us in the October 5th 1970 '13 Hole' Postcard. When this was slotted into the April 20th 1970 '13 Symbol' Cipher it read like so: "This is the Zodiac speaking. By the way have you cracked the last cipher I sent you? My name is Fk, I'm crackproof". The Zodiac Killer had in effect answered the request of Dr. Marsh, although in a rather devious manner. However, Dr. Marsh issued this challenge on October 22nd 1969 and the 340 Cipher came before the 13 Symbol Cipher.     

One of the most prominent features in the 340 Cipher is the sixth line where he corrects a forward facing K to a backwards facing K, similar in nature to the way he reversed the "Fk, I'm crackproof" phrase on the 13 Hole Postcard. The proximity of F and K can be noted in these two outstanding features - and possibly the Zodiac thought it mildly amusing to provide his name to Dr. Marsh in the extremely "complicated" manner of reversing his name or initials. Everybody was searching for a stunningly complicated solution to the 340 character cipher as Dr. Marsh had requested, so the Zodiac Killer gave us the complete opposite.

The connection between the 13 Hole Postcard and 13 Symbol Cipher was not only bound in the "Fk, I'm crackproof" solution, but the two phrases he used in each communication didn't go unnoticed either. The Zodiac Killer inextricably tied the two correspondences together using similar phraseology, such as "What is the price tag now" and "how much money you have on my head now". On January 29th 1970, the Yellow Cab Company put up a thousand dollar reward for any information leading to the arrest of the Zodiac Killer. In addition, the Teamsters Union which represents the Yellow Cab Company were reported in the San Francisco Chronicle to be considering offering a further reward on February 8th 1970 in the case of Paul Stine and Charles Jarman (another taxicab murder victim). This news was likely what prompted the Zodiac Killer to open this communication with the words "I am mildly cerous as to how much money you have on my head now".  Or could there be another more subtle clue in these phrases with regard to his name?

Where on the April 20th 1970 letter and throughout much of his communications to date (including the 340 Cipher) could money or a price tag be found on a head? The 13 Symbol Cipher letter carried a dated 1966 Franklin D. Roosevelt stamp, where indeed "money" or a "price tag" could be found 'on' the head of Franklin D. Roosevelt. Was this a subtle hint to his first name of "Franklin" or "Frank". This would satisfy the F part of "Fk, I'm crackproof" - but as stated earlier,  very speculative to say the least.

Another communication where he promised us his name was the October 27th 1970 'Halloween' Card, in which he gave us an odd-looking symbol and placed it on the left side of the envelope and the Halloween Card inner, followed by the letter Z. The correct way to address an envelope is to write the sender's name and address in the top left corner of the envelope, shown here on a Youtube video, and the recipient address (in this case Paul Avery) in the center of the envelope. Therefore, this strange symbol could equate to the sender's name. Since we are looking for the initials of the Zodiac Killer (which may be reversed for a third time), it is extremely promising that we have an F looking character on the right side yet again. I don't like too much manipulation and the use of mathematics anymore, but on this occasion I will choose the path of least resistance and take the 7 and 4 dots to equal 11 (K being the 11th letter of the alphabet) - and therefore give us a joined K and F for his name on the return section of the envelope. Unfortunately, manipulation such as this always leads to the possibility of multiple solutions, so we have to be guarded to any conclusions we make. Finally, I would like to take a look at the sister card to the Halloween Card mailed in the December of 1990. It too promised us his name.       

The greeting card was again from our Secret Pal just like the Halloween Card twenty years earlier - it began with the message "FROM YOUR SECRET PAL CAN'T GUESS WHO I AM YET? WELL, LOOK INSIDE AND YOU'LL FIND OUT". Then promised to keep us guessing on the card inner.

All the Zodiac Killer added to the card inner was a Xerox copy of some "keys". It really couldn't be any simpler. The card outer stated "From your secret pal, can't guess who I am yet? Well, look inside and you'll find out" followed by "keys". This may very well be the final really complicated answer to the challenge laid down by Dr. Marsh all those years earlier. The surname of Keys, Keyes or Keays would satisfy the K of FK, from the phrase "This is the Zodiac speaking. By the way have you cracked the last cipher I sent you? My name is Fk, I'm crackproof".

This mocking response to Professor D.C.B. Marsh, who requested that the Zodiac Killer "send The American Cryptogram Association a cipher code - however complicated - which will truly and honestly include his name" was probably befitting of the Zodiac Killer. The answer may have been simpler than we could ever of imagined. Return to sender: Franklin Keys (or alternate options above).

Of course, I am not claiming this to be the answer regarding the identity of the Zodiac Killer, but it would be rather appropriate for the Zodiac Killer to have begun his letter writing campaign with Franklin on the stamps of his July 31st 1969 trinity of communications, and ended with his surname of Keys in 1990 - and thumb a finger to all the cipher experts trying vainly to crack his extremely complicated ciphers, when the answer was literally staring us in the face all along. 

THE 340 CIPHER WAS CRACKED ON DECEMBER 3RD 2020 BY DAVE ORANCHAK, SAM BLAKE AND JARL VAN EYCKE, SO THIS EARLIER ARTICLE SHOULD BE VIEWED IN RESPECT TO RECENT DEVELOPMENTS.

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

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

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

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

THE 340 CIPHER WAS CRACKED ON DECEMBER 3RD 2020 BY DAVE ORANCHAK, SAM BLAKE AND JARL VAN EYCKE, SO THIS EARLIER ARTICLE SHOULD BE VIEWED IN RESPECT TO RECENT DEVELOPMENTS.

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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 could have been 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.

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 considered to be the Zodiac Killer offering us his name. 

It could be argued that this cipher was not only created because of the newspaper article, but designed 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 offering of  A Few Words on Secret Writing, that the very beginning of the essay shows the alphabet being split into two halves of thirteen 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 the Zodiac wasn't going to achieve with any reasonable possibility of decryption, 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 could possibly have been 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 crafted at a similar time. See image here for explanation.
 
"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, therefore 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 a plausible explanation for a correlation between the two, with 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 claimed that any cipher created by Zodiac can be solved by Edgar Allan Poe?

The last confirmed correspondence by the Zodiac Killer was the 'Exorcist' letter mailed on January 29th 1974, making the 1990 'American Greetings' or 'Eureka' card seem distant from the activities of the Bay Area murderer. We will therefore look at Unabomber Ted Kaczynski, whose known criminal activities were committed between 1978 and 1995. This will be working on the hypothesis that the Eureka 'Secret Pal' card was chosen separately and independently from the Zodiac Killer's 'Halloween' card mailed to the San Francisco Chronicle on October 27th 1970, twenty years previously. It could have been sent 'piggybacking' on the Zodiac communications, but after two decades it is more likely a case of coincidence.

There is an excellent thread discussing this Christmas card on the Zodiac Killer Site forum, but here we would like to approach the 'Eureka' card from a more simplistic angle and the reasoning behind the xeroxed or photocopied keys contained within the communication.

The wording on the card exterior read; "FROM YOUR SECRET PAL CAN'T GUESS WHO I AM YET? WELL, LOOK INSIDE AND YOU'LL FIND OUT..." and once opened it revealed: "...THAT I'M GONNA KEEP YOU GUESSIN'! HAPPY HOLIDAYS, ANYWAY".  The suggestion, is that once the card is opened it will reveal the identity of its author - and although there is no written message within the Christmas card - there are two photocopied keys. One would therefore like to believe, that this is the clue to the author's identity in the form of an image. Here is a manufactured image of how the presentation may have looked before a negative was produced. 

Many theories have been presented in respect to the image on the left, including the keys being arranged to mimic Groucho Marx smoking a cigar (when viewed upside down) and a play on the words "keys" and "chain". A Unazod article entitled 'A New Zodiac Missive' shows the writing on the envelope of the 'Eureka' card in comparison to a letter mailed to Mrs Irene Preston from Ted Kaczynski in the December of 1990. It is a compelling comparison. However, is there a more simplistic answer to the identity of the author using the image mailed to the San Francisco Chronicle.

"Theodore John Kaczynski born May 22, 1942), also known as the Unabomber, is an American domestic terrorist. A mathematics prodigy, he abandoned an academic career in 1969 to pursue a primitive lifestyle. Then between 1978 and 1995 he killed three people, and injured 23 others, in a nationwide bombing campaign targeting those involved with modern technology, in an attempt to start a revolution. In conjunction, he issued a social critique opposing industrialization and advancing a nature-centered form of anarchism. The initial 1978 bombing was followed by bombs sent to airline officials, and in 1979 a bomb was placed in the cargo hold of American Airlines Flight 444, a Boeing 727 flying from Chicago to Washington, D.C. A faulty timing mechanism prevented the bomb from exploding, but it released smoke, which forced an emergency landing. Authorities said it had enough power to "obliterate the plane" had it exploded. As bombing an airliner is a federal crime, the Federal Bureau of Investigation became involved in the case, designating it UNABOM for UNiversity and Airline BOMber. (U.S. Postal Inspectors, who initially had the case, labeled the suspect the "Junkyard Bomber" because of the material used to make the mail bombs. In 1979, an FBI-led task force that included the ATF and U.S. Postal Inspection Service was formed. The task force grew to more than 150 full-time personnel, but minute analysis of recovered components of the bombs and the investigation into the lives of the victims proved of little use in identifying the suspect, who built his bombs primarily from scrap materials available almost anywhere. The victims, investigators later learned, were chosen irregularly from library research". Wikipedia.

​Could Ted Kaczynski have used a photocopying machine during this library research and mailed the 'Eureka' card to the San Francisco Chronicle in the December of 1990? Ted Kaczynski was later to send carbon copies of his 'Manifesto' to various publications: "Last June and July, the Unabomber mailed carbon copies of the 62-page, single-spaced manifesto to the New York Times, Washington Post, Penthouse magazine and Tom Tyler, a UC Berkeley psychology professor. Tyler appears to have received his copy as something of an afterthought by the bomber. His only known connection to the case is that he had been quoted in a Bay Area newspaper commenting on the behavior of the serial killer". Los Angeles Times.

​"Beginning in the 1970s, Kaczynski targeted universities and airlines, injuring 23 people and killing three. After a threat mailed to the San Francisco Chronicle in June 1995, the USPS scrambled to come up with a plan to inspect all air mail packages out of California. For six days, USPS did not accept packages or letters bigger than 12 ounces. The threat, Kaczynski later admitted through an anonymous letter to the New York Times, was a prank. He had played the system against itself—delivering anonymous taunts through the mail and disrupting the very mail-delivery system". The Atlantic. 

The 'Unabomber' Ted Kaczynski would either mail his explosive devices using the postal service or hand deliver - so were the USPS (United States Postal Service) keys xeroxed and mailed with the 'Eureka' card to the San Francisco Chronicle, as a form of taunting towards the authorities he so obviously railed against in a game of cat and mouse - and within the image a clue to his name using only two alphabetical letters. The etched writing on the keys of USPS DO NOT DUPLICATE could be considered ironic with regards to the xeroxed image supplied.   

Ted Kaczynski claimed his first main casualty, when John Hauser, a captain in the Air Force was partially blinded in one eye and lost four fingers when receiving a mailed bomb in 1985. Hugh Scrutton, who owned a California computer store, in 1985 became the first fatality of the bombing campaign, followed in 1994 by Thomas J Mosser, an advertising executive and Gilbert P Murray in 1995, president of a lobbyist timber industry group. 

​Earlier in Ted Kaczynski's bombing campaign, on June 10th 1980, Percy Wood, president of American Airlines opened a package containing a book called 'Ice Brothers' packed with explosives, from which he narrowly cheated death. The device was constructed using wood - the victim's last name was Wood and the return address was from a street named Ravenswood. ​Was Ted Kaczynski playing a game of words with investigators in his attempted murder of Percy Wood? Inside the chiseled out section of the book Ted Kaczynski had inserted a small piece of metal in which the letters "FC" had been punched into its face. These two alphabetical letters would be used throughout his bombing campaign to identify his work to authorities. "In all, 16 bombs—which injured 23 people and killed 3—were attributed to Kaczynski. While the devices varied widely through the years, all but the first few contained the initials "FC." Inside his bombs, certain parts carried the inscription "FC," which Kaczynski later asserted stood for "Freedom Club."

One of Kaczynski's tactics was leaving false clues in every bomb. He would deliberately make them hard to find to mislead investigators into thinking they had a clue. The first clue was a metal plate stamped with the initials "FC" hidden somewhere (usually in the pipe end cap) in every bomb. One false clue he left was a note in a bomb that did not detonate, which reads "Wu—It works! I told you it would—RV".  Wikipedia.

One can see that Ted Kaczynski was fond of leaving cryptic clues for investigators to find - so is it any great leap of faith that Ted Kaczynski would choose a Christmas card beginning with the lines "From your secret pal. Can't guess who I am yet?  Well look inside and you'll find out". So If Ted Kaczynski was to leave his name within the 'Eureka' card, then it had to be connected with the xeroxed image, and quite possibly may have been two initials in length. The image presented is that of 'Two Keys", the initials of which are TK, representing Ted Kaczynski. ​It's a simplistic analysis - but it's a simplistic image, with limited room for maneuver. 

The following article is an updated version of a previous post, expanded and covered in greater detail. It is not particularly a line of investigation that I subscribe to, but it attempts to compare the Zodiac Killer's Halloween Card mailed on October 27th 1970 with the Harper Lee novel 'To Kill a Mockingbird', published in 1960 and turned into a film in 1962 featuring Gregory Peck, Robert Duvall, Mary Badham and Phillip Alford. Set in the fictional town of Maycomb, the film explored the deep set racial undertones prevalent in American society, brought to the forefront, as lawyer Atticus Finch fought to defend a black man accused of rape in Alabama. The film won three Academy Awards including Best Picture and Best Actor. 

The most reclusive character in the film was Arthur "Boo" Radley, who went by the shortened version Boo Radley. The first thing to be noticed on the Halloween Card envelope is the misspelled name of the reporter Paul Avery to Paul Averly- which emphasizes the 'ley' section. On the inside of the card he places the word BOO in bold letters. Now we have two parts of our puzzle, "Boo" and "ley". To complete the name Boo Radley requires us to search for "Rad", which is not far away. It crosses the "LAV" of "SLAVES" on the Halloween Card paradice and slaves configuration - which rather fortunately was underlined on the envelope  containing the reporter's name. The Zodiac Killer may not have given us a cipher but had he given us "Boo Radley". 
 
Boo Radley was a much misunderstood character in the novel, feared and rumored upon by the local schoolchildren. He was described by Jem (brother of Scout Finch) as "6 1/2 feet tall... dined on all the raw squirrels and cats he could catch... you could never wash the blood off... there was a large scar that ran across his face... his eyes popped and he drooled most of the time".  In fact, Boo Radley's house and chicken yard backed onto Maycomb School. Funny that - I remember Arthur Leigh Allen slaughtered chickens and squirrels and was never far from schools - but coincidence aside - we shall move on.

The children feared the Radley House and garden, believing the trees were poisoned, however, in one such tree a knot-hole existed, that would ultimately bridge a friendship between Boo Radley, Scout and Jem. Periodically the reclusive Boo Radley would  place objects in the knot-hole for Scout and Jem to find. This was his outlet to the world. On various days the two children would find presents he had left - which included carved soap figures, a ball of twine, chewing gum, a broken pocket watch, an Indian medal, and an aluminium knife on a key chain - many deposited in pairs, one for each child. This was their 'Tree Treasure'. In fact, 'Tree Treasure' was one of the tracks created for the musical score accompanying the film, composed by Elmer Bernstein. Two other tracks on the musical score were titled  'Boo Who' and 'Peek-a-boo.'. What a coincidence. 

The Halloween Card had a knot-hole in the tree with the words "peek-a-boo" circled around it.. Peek-a-boo is the act of concealing ones face behind the hands or other object, before suddenly appearing back into view and uttering the words peek-a-boo. It can be seen in Wikipedia that many variations involve trees, similar to the depiction on the Halloween Card, where 'Hiding behind that tree' is added. See here. That eye was certainly hiding in the Halloween Card tree - was it not. Didn't the Zodiac Killer hide behind a tree at Lake Berryessa and hide his face behind a mask?. When he eventually came into view his identity was concealed. When the Halloween Card was removed from the envelope, it goaded us  with the introduction "I feel it in my bones, you ache to know my name, and so I'll clue you in" - and once opened it revealed the word "BOO". I know what your thinking "Boo Who."  Well, I had to squeeze it in.

The Eureka Card, mailed in the December of 1990 was the sister card to the Halloween Card, and was very similar in design. It too began with a message from our 'secret pal', yet this time it had a present from Zodiac - not an aluminium knife and pocket watch on a key chain - but a photocopy of a pair of keys on a key chain. 

In the novel Scout and Jem made a snowman, constructed with mud, then layered with snow - a theme many believe was suggestive to the racist overtones of the story. A snowman is depicted on the Eureka Card, with what appeas to be Groucho Marx imagery on the face. Jem and Scout built this snowman because of their dislike of a local resident down the street, but their father Atticus intervened and told the children to disguise it because it so resembled the local resident they were poking fun at. To placate their father, they placed Miss Maudie's hat on it. The resident they so disliked was called MR AVERY - now that is a coincidence, along with December 25th 1962 release date of the film in Los Angeles, California. The Eureka Card was mailed sometime in December and depicted a Christmas scene. Facing the snowman was a cute rabbit. I hope Arthur Leigh Allen didn't slaughter rabbits as well as chickens and squirrels. 

Incidentally, Scout and Jem went to a Halloween celebration. In the book on Chapter 28, the schoolchildren are encouraged to dress up in the local agricultural produce of Maycomb for the Halloween night pageant rather than go trick or treating. Scout is dressed as a piece of ham. While traveling home after the pageant, Jem and Scout are attacked by somebody and rescued by Boo Radley. As we all now know, Bob Ewell is later found dead under a tree with a knife stuck in him. It is curious that the skeleton on the Halloween Card is also wearing agricultural produce. Is that a pumpkin I see? And that tree keeps reappearing. 

Was this card based on the Lake Berryessa attack, or could the Zodiac have been peeking out, playing hide and seek in the Julius Khan playground in the Presidio. I feel something in my bones. Anyway, here ends the story. The only question left to ask is, have I now created a second piece of fiction?

The final confirmed letter mailed by the infamous Zodiac Killer to the San Francisco Chronicle on January 29th 1974 has been commonly referred to as the Exorcist Letter. This sixty-one word correspondence appeared to mock the 1973 movie The Exorcist, directed by William Friedkin and based on a novel by William Peter Blatty published in 1971, chronicling the demonic possession of a twelve-year-old girl, Regan MacNeil. William Peter Blatty spent long nights in a secluded Lake Tahoe cabin crafting images of good and evil, religion, faith and the afterlife, that would eventually go on to make movie history and court its fair share of controversy along the way. 

The letter is short, reminiscent of much of the Zodiac Killer's later contact with authorities, but as well as mentioning The Exorcist movie, the letter, in rather disjointed fashion, breaks into a Mikado recital once again, recalling memories of the Little List Letter mailed three and a half years previously on July 26th 1970. But this time the foreboding 'Tit Willow' seemed contemplatory in this context, possibly marking the end of the Zodiac reign - and to this day is still often quoted as the murderer's epitaph. The third and final section issued the usual threat of more murders, capped off with Asian style symbols in the form of a cryptic message. Like much of his later correspondence there is little substance here, but we will attempt to delve a little deeper into the Exorcist Letter and find any links that may be relevant or otherwise, as to why he wrote the letter in the first place. This is not a theory, just an examination into where the Zodiac Killer may have been drawing his inspiration.       

The Little List Letter mailed to the San Francisco Chronicle on July 26th 1970 heavily featured the Gilbert and Sullivan stage play, The Mikado. One section loosely quotes 'a more humane Mikado',  followed by the more extensive paraphrasing of Act 1 Part 5a, 'As some day it may happen'. The curious thing, is that the Zodiac Killer's version of the Little List mimics closer to the Groucho Marx version in the Bell Telephone Hour (1960) than the original Gilbert and Sullivan play. Visit here for the full audio collection: Gilbert Sullivan-The Mikado audio. A thread at the Zodiac Killer Site Forum also covers this topic in detail. Groucho Marx would possibly appear again, depicted in the American Greetings Card or Eureka Card, mailed by either the Zodiac or a copycat in the December of 1990.

The Eureka Card was reminiscent of the Halloween Card mailed some 20 years earlier. It begins with the words FROM YOUR SECRET PAL CAN'T GUESS WHO I AM YET?  WELL, LOOK INSIDE AND YOU'LL FIND OUT...  and once opened stated ... THAT I'M GONNA KEEP YOU GUESSIN'! HAPPY HOLIDAYS, ANYWAY. The scene portrayed on the Christmas card  was of a snowman disguised in a Groucho Marx style nose and glasses. In front of the snowman was a rabbit or hare apparently gazing up at the wintry scene. One cannot help thinking the Zodiac Killer chose his cards for a reason.

Another interesting connection was noted on viewing the Tom Hanson Zodiac movie from 1971, in that the killer wore a Groucho Marx style nose and glasses in one scene from the movie. View the scene and thread at ZodiacKiller.com. But this was not the only possible film connection to the Groucho Marx disguise featured on the 1990 Eureka Card.  

Terror Train was released in 1980, directed by Roger Spottiswoode and starring Jamie Lee Curtis, Ben Johnson and David Copperfield. During New Year celebrations at the students fraternity house Sigma Phi, a prank backfires on Kenny Hampson (Derek MacKinnion). Mentally scarred by the event, this forms the basis of revenge when the students responsible for the prank board a private train hosting a fancy dress party, exactly three years later. On boarding the train one of the students is stabbed, but his friends believing it is a prank, continue along unconcerned. The killer collects the victim's Groucho Marx mask, follows them onto the train and seeks his revenge, one by one. The movie was primarily a thriller/slasher, filmed in Canada from November 21st to December 23rd 1979 and released by Twentieth Century Fox in the October of 1980.

But can we connect Groucho Marx to the Exorcist Letter? Not directly, but by association. The Zodiac Killer described The Exorcist as, "the best satirical comedy that I have ever seen". Well, this may not be the case, however, the genesis of the movie may well have been born with the help of a comedy genius - that of Groucho Marx. The Exorcist author, William Peter Blatty, was a close friend of Groucho Marx, and there was an intention by Marx to dress as the priest Father Lankester Merrin from the movie and appear on the set of the Exorcist film, but due to scheduling matters the comedic entrance never materialized. But in one episode of the popular You Bet Your Life series, hosted by Groucho Marx, William Peter Blatty was a contestant and walked away with a prize of $10,000. When he was asked what he was going to do with the money, he stated he was to take some time off  to work on a novel. That novel was the acclaimed inspiration for the movie The Exorcist.  

Groucho Marx was a lifelong fan of the Gilbert and Sullivan operas, appearing as Ko-Ko in a production of the Mikado, on NBC's Bell Telephone Hour in 1960. He also recited Tit Willow in 1960 and on the Dick Cavett Show on March 20th 1970. Wikipedia. Therefore, Groucho Marx can be associated through the Little List Letter mailed on July 26th 1970, the Exorcist Letter on January 29th 1974 and the Eureka Card in the December of 1990. However, there is a little more background.

William Peter Blatty released a novel in 1966, entitled Twinkle,Twinkle Killer Kane. It achieved little commercial or critical acclaim. View accompaniment. The story centers on a psychiatrist, 'Killer Kane' (Hudson L Kane) and explores faith, humanity and irony. He enters a madhouse to determine if its residents, comprised of soldiers and astronauts are actually mad or just putting on an act. This results in extended interaction with resident Manfred Cutshaw on the concept of God. In the story Kane postulates "every man who has ever lived has been born with desire for perfect happiness. But unless there is an afterlife, fulfillment of this desire is a patent impossibility". It was to be later rewritten and published under the new title 'The Ninth Configuration' in 1980, attempting to explore the marginal line of sanity over insanity. It failed to inspire the public on its cinematic release.