Alan Keel, Criminalist at the San Francisco Police Department, San Francisco, California from 1996 to 1999 "revealed that there were two letters in possession of the department that, in contrast to the "true" Zodiac letters, had abundant saliva and DNA-containing oral epithelial cells on them, that DNA was easily extracted from these two letters, and that the DNA extracted from these two letters matched between them. These two letters were considered forgeries, since the "true" Zodiac verifiable letters had not been licked by the sender". Mike Rodelli, an avid Zodiac researcher, who conversed with Alan Keel, revealed "In contrast (to earlier communications), Keel analyzes two other letters, one of which is the 1978 forgery, and finds that this letter and one of the 1974 letters are loaded with saliva and cells. He then easily extracts DNA from both of these letters using the more primitive DNA technology of that time and finds that the DNA matches between those two letters, thus proving that one person sent both".  Mike Rodelli.

​If you take a look at the San Francisco Police Department DNA report, the 1974 Exorcist letter is the only letter that year to produce any viable results, described as "cells found". The S.L.A letter was totally disregarded, and the "Citizen" and "Red Phantom" communications had no entry in comments. If Alan Keel is correct in his assertion, then the Exorcist letter would enter the classification of unlikely Zodiac correspondences - ones that had "been licked by the sender". 

In the latest round of DNA testing in the Zodiac case, two of the three July 31st 1969 communications have again come under scrutiny. These were unavailable at the time the San Francisco Police Department DNA testing was undertaken. It is apparent that these letters have struggled to give up their secrets, as have other communications listed in the report, which includes the October 13th 1969 'Paul Stine' letter, the November 8th 1969  'Dripping Pen' card, the November 9th 1969 'Bus Bomb' letter, the December 20th 1969 'Melvin Belli' letter, the April 20th 1970 'My Name Is' letter, the April 28th 1970 'Dragon' card and the June 26th 1970 'Button' letter. In total, nine consecutive communications that, it is fair to say, have produced little in the way of a recognizable DNA fingerprint. Most of these are labelled in comments as "few cells".

The only remaining communications in the DNA report subsequent to June 26th 1970 which produced any notable results, classified as "cells found", were:
[1] The July 24th 1970 'Kathleen Johns' letter.
[2] The July 26th 1970 'Little List' letter, and
[3] The January 29th 1974 'Exorcist' letter.
And all three had one crucial element in common - The Mikado. 

The 'Kathleen Johns' letter began the trilogy by stating "So now I have a little list, starting with that woeman + her baby that I gave a rather intersting ride for a coupple howers one evening a few months back that ended in my burning her car where I found them".  This would be continued two days later with the paraphrasing of two of Gilbert and Sullivan's acts from The Mikado. The first section of the 'Little List' letter pulls lines from the A more humane Mikado, where the author uses the words billiard along with crooked cues and twisted shoes.
This correspondence goes on to paraphrase Gilbert and Sullivan's  As some day it may happen, performed by Ko-Ko, as did the future correspondence of the Exorcist Letter in 1974, when reciting Tit-Willow from Ko-Ko's On a tree by a river, part of Act Two.  

We don't know the exact concentrations of DNA retrieved from these three communications, but it is evident that these were the only three letters classified as "cells found" - and all three made reference to The Mikado. If "cells found" could be proven as "saliva" found, and the "true Zodiac verifiable letters had not been licked by the sender" according to Alan Keel, then this could indicate that all The Mikado letters were not authored by the Zodiac Killer. An extremely hard notion to accept when we look at the handwriting and design of each of these correspondences. 

One can understand why certain sections of the Zodiac communications were withheld from the public, such as his bomb diagrams - yet the entire July 26th 1970 'Little List' letter was not released to the newspapers until October 12th 1970. This innocuous correspondence for the most part was withheld for two and a half months until it featured in a San Francisco Chronicle article entitled 'Gilbert and Sullivan Clue to Zodiac', in tandem with the subsequent October 5th 1970 '13 Hole' postcard. If the 'Little List' letter and '13 Hole' postcard were authored by the Zodiac Killer, then it is notable that, despite putting a lot of effort into this rather lengthy correspondence on July 26th 1970, he failed to make any issue about the complete absence of newspaper coverage that this letter received when he mailed his next correspondence. It is believed he repeated his victim count of 13 because his last letter hadn't been published in the newspapers. But could it have been the case that the Zodiac Killer wasn't reaffirming the victim count of 13 because his previous correspondence wasn't published, rather, he was unaware somebody had mailed the 'Little List' letter in his name? Hence his lack of concern about "front page coverage", or for that matter, any coverage at all. 

If the Zodiac Killer hadn't written any of The Mikado communications, then he also wasn't claiming the abduction of Kathleen Johns on March 22nd 1970. In fact, the notion of a killer driven by the theatrical librettos of Sir William Schwenck Gilbert would be quashed entirely. It is extremely difficult to sell a story of a Zodiac Killer who didn't author any of The Mikado communications, let alone all of the 1974 communications - so the curtain call will be cancelled for this performance only. 

In 2002, a new round of DNA testing was performed on some of the Zodiac letters by Dr. Cydne Holt, yet despite an ABC Primetime documentary opening up with the promising statements of "But today thanks to new crime scene technology there's reason to believe time may have run out on Zodiac. Somewhere, perhaps on the back of this postage stamp or in the seal of this envelope, may be microscopic clues that will now finally lead police to the killer", it appears the early optimism of a Zodiac breakthrough has soured. Dr. Cydne Holt stated "We are hoping to be able to get some genetic information about the individual or individuals that did seal these envelopes or place stamps on them". 

It is patently obvious by these statements the importance of securing genetic material from the sealed sections of the stamps and envelopes. Any testing performed on the outside of the stamps and envelopes is absolutely meaningless from a standpoint of identifying the person who was present at the time of their sealing. Since this documentary aired, it is now claimed that this is exactly what transpired in the laboratory - with the letters being swabbed from the outside. The only reason to perform such a pointless procedure, would be if you had failed to find any or enough saliva on the sealed section of the envelopes or stamps tested, yet were determined to carry on with the 'show'. In other words, the ABC Primetime documentary ended up becoming a circus sideshow for ratings, rather than applying the correct procedure which was promised in the opening statements of the documentary. This led to previously ruled out suspects getting a new day in the sun. Despite the fact this round of testing has been routinely discredited by many in the Zodiac community, the documentary has inadvertently revealed so much more about the Zodiac case. 

The San Francisco Police Department DNA report of communications tested in the late 1990s, indicates that "few cells" were found on any of the Zodiac communications up to and including the June 26th 1970 'Button' letter. The letters subsequently tested after this date were all labelled as "cells found". The Kathleen Johns, Little List, Exorcist and 1978 letters all contained potentially measurable genetic material.

​Even Criminalist Alan Keel (according to Mike Rodelli) revealed: "In contrast (to earlier communications), Keel analyzes two other letters, one of which is the 1978 forgery, and finds that this letter and one of the 1974 letters are loaded with saliva and cells. He then easily extracts DNA from both of these letters using the more primitive DNA technology of that time and finds that the DNA matches between those two letters, thus proving that one person sent both."  The only other letter in 1974 processed for DNA (where cells were found), was the Exorcist letter. Therefore, the two letters described by Alan Keel "as matching between them" had to be the 1978 letter and the Exorcist letter. If the 1978 letter is 'not an authentic Zodiac letter', then the Exorcist letter is 'not an authentic Zodiac letter' either.​

So, here we have four communications that provided notable results, but none were featured in the 2002 ABC Primetime documentary. The fact that the 1978 letter or Exorcist letter were apparently never tested in the documentary, despite being "loaded with saliva and cells", should be enough evidence to conclude that this round of testing didn't consider these two letters as reliable Zodiac communications. Whereas the majority of Zodiac sleuths consider the Exorcist letter to be genuine Zodiac material, the findings of Alan Keel and the reluctance to use this letter at all in the documentary, seems to reject this premise. The documentary made specific reference to the July 31st 1969 letters, the October 13th 1969 Paul Stine letter and the November 8th 1969 'Dripping Pen' card, all of which apparently contained "few cells" according to the San Francisco Police Department DNA report only two years earlier, but made no mention of the July 24th 1970 Kathleen Johns letter or the July 26th 1970 Little List letter, both of which were labelled as "cells found". If you were to choose letters for testing, surely you would choose ones that contained more cells on the sealed sections of the envelopes and stamps. 

Despite the controversy this documentary has generated, it did clearly state "Dr. Holt has already detected the possible presence of Zodiac's DNA in the seal of the envelope that contained the greeting card, and just in case that fails to provide a full DNA profile, she also prepares to look for DNA  beneath the stamps on two of these three letters (July 31st 1969 letters)." 

They would ultimately claim a partial DNA fingerprint which they used to rule out Arthur Leigh Allen, Kjell Qvale and Charles Collins as the infamous Zodiac Killer. But many believe they failed to find enough material from the sealed sections of the communications and thus resorted to swabbing the outside of the envelopes and stamps. However, Dr. Cydne Holt did affirm that she needed to find DNA matching between the envelope seal of the greeting card and the July 31st 1969 letters, stating "Depending on whether those DNA's match each other, might allow me to include or exclude Arthur Leigh Allen as potentially contributing the DNA on the Zodiac letters". The act of later ruling out all three suspects, including Arthur Leigh Allen, implied she had found a DNA match between these two separate correspondences. Even if she had swabbed the outside of the letters to keep the 'show' on the road, it would still imply (using her words) that a match between separate communications must be found before ruling Arthur Leigh Allen in or out as "contributing the DNA on the Zodiac letters". But what are the realistic chances of finding a DNA match between the Dripping Pen card envelope and one of the July 31st 1969 letters by swabbing the outside of each correspondence? The concluding elimination of the suspects near the finale of the show seemed to suggest, one way or another, she did. The subsequent reluctance of the participants in the documentary to confirm the validity of the testing and the new round of testing in 2018, appears to negate the ABC Primetime documentary as a reliable venture. 

But here we are again in 2019, waiting on results from the latest attempt to secure a viable genetic fingerprint of Zodiac to submit to GEDmatch. "Vallejo police Detective Terry Poyser, who has worked the Zodiac case for four years, said his agency has submitted two envelopes that contained letters from the Zodiac Killer for a type of advanced DNA analysis that previously had not been available in the case. Poyser declined to identify the lab, but said it would attempt to obtain a full DNA profile from saliva on the envelope flap and stamps. He said he expected to have results back from the lab as soon as in the next few weeks, and almost certainly by summer. The department has three letters and two envelopes from the Zodiac, Poyser said. The envelopes each have a double stamp, which Poyser said was a trademark of the Zodiac. They originally were sent to the San Francisco Chronicle and the San Francisco Examiner, he said. The third letter was sent to the Vallejo Times-Herald, but does not have an envelope with it, he said. Allen largely was cleared as a suspect in 2002, when investigators obtained a partial DNA sample from the envelopes that didn't match his. Poyser said that DNA profile only had a few markers on it, less than half of the genetic points needed to definitively clear or identify a suspect". Sacramento Bee.

Again, the emphasis squarely focuses on the July 31st 1969 envelopes and stamps, despite the much earlier Zodiac correspondences showing a tendency toward "few cells" being discovered. The July 31st 1969 letters were not available during the San Francisco Police Department DNA testing in the late 1990s, but why are the Kathleen Johns and Little List letters seemingly passing under the radar again in this latest round of testing, when the 2000 SFPD report clearly states that "cells were found" on these communications? The apparent omission of the Exorcist letter for submission this time round, despite being "loaded with saliva and cells" according to Criminalist Alan Keel, may further bolster the notion that law enforcement have no confidence in this being a Zodiac letter. Does the apparent reluctance to consider the Kathleen Johns and Little List letters for testing in 2018, suggest an equal lack of confidence?

Were the July 31st 1969 letters submitted in 2018 because current law enforcement do believe in the validity of the findings of the 2002 documentary? After all, Detective Poyser did state "Allen largely was cleared as a suspect in 2002, when investigators obtained a partial DNA sample from the envelopes that didn't match his. Poyser said that DNA profile only had a few markers on it, less than half of the genetic points needed to definitively clear or identify a suspect". Law enforcement must believe that DNA was found on the sealed side of the envelopes and stamps from the July 31st 1969 letters, hence why they are focusing on these communications again, in the hope of finding a full or more complete DNA profile using more advanced technology. If law enforcement really believed the DNA testing from 2002 was only achieved by swabbing the exterior of the July 31st 1969 letters, then their unreserved targeting of these communications would be misplaced. But they seemingly don't believe this to be the case. ​They apparently don't share the reservations of the Zodiac community. 

It could be regarded as contradictory that the majority of the Zodiac community believe the Exorcist letter to be a genuine Zodiac correspondence - one that is widely touted as the final confirmed communication by the Bay Area murderer by ardent sleuths and law enforcement alike, which according to Alan Keel is "loaded with saliva and cells" - yet was seemingly roundly ignored in 2002, and once again in 2018, when this letter by all accounts should be the first port of call regarding biological material. It strongly suggests that the exhibited confidence in the January 29th 1974 letter is totally misplaced - and the Zodiac Killer may never have returned in 1974 at all.

DNA AND THE DAVID TOSCHI CONTROVERSY

Mike Rodelli wrote in his book, 'The Hunt for Zodiac:The Inconceivable Double Life of a Notorious Serial Killer', that Alan Keel, Criminalist at the San Francisco Police Department, San Francisco, California from 1996 to 1999 "revealed that there were two letters in possession of the department that, in contrast to the "true" Zodiac letters, had abundant saliva and DNA-containing oral epithelial cells on them, that DNA was easily extracted from these two letters, and that the DNA extracted from these two letters matched between them. These two letters were considered forgeries, since the "true" Zodiac verifiable letters had not been licked by the sender." Mike Rodelli also stated "In contrast (to earlier communications), Keel analyzes two other letters, one of which is the 1978 forgery, and finds that this letter and one of the 1974 letters are loaded with saliva and cells. He then easily extracts DNA from both of these letters using the more primitive DNA technology of that time and finds that the DNA matches between those two letters, thus proving that one person sent both."  

The San Francisco Police Department DNA report clearly states that the 1978 letter was tested for DNA (which was obtained) and deemed 'not an authentic Zodiac letter'. The only other letter in 1974 processed for DNA (where cells were found), was the Exorcist letter. Therefore, the two letters described by Alan Keel "as matching between them" had to be the 1978 letter and the Exorcist letter. If the 1978 letter is 'not an authentic Zodiac letter', then the Exorcist letter is 'not an authentic Zodiac letter' either. But how can the San Francisco Police Department claim that the 1978 letter is not an authentic Zodiac communication, when you don't have the Zodiac Killer's DNA to test it against? The only two possible answers, are that (Inspector) David Toschi, accused of forging the 1978 letter, had his DNA compared to the 1978 letter and it matched, thus proving it couldn't have been written by Zodiac, or the DNA markers on the 1978 letter confirmed it was written by a woman. Females typically have two of the same kind of sex chromosome (XX), and are called the homogametic sex. Males typically have two different kinds of sex chromosomes (XY), and are called the heterogametic sex. 

If we conclude that David Toschi hadn't forged either the 1978 letter or the Exorcist letter, and the "DNA matched between them" as stated by Criminalist Alan Keel, then we are left to conclude that both were authored by a woman. However, if this had been determined to be the case, why not release this to the public and officially exonerate David Toschi beyond any doubt and clear this perceived stain on his character. This would be the least you would do for a respected and dedicated law enforcement officer, who served the San Francisco Police Department from 1952 to 1987. The fact they didn't do this, suggests that both the 1978 letter and Exorcist letter were not authored by a woman. But this once again places the spotlight back onto David Toschi as the only other option. 

It has been claimed that a palm print discovered on the Exorcist letter has ruled out Arthur Leigh Allen as the contributor. Michael Butterfield wrote "The San Francisco Police department also announced that Allen’s palm print did not match the palm print found on the Zodiac’s “Exorcist” letter of 1974". Zodiac Killer Facts. If this palm print ruled out Arthur Leigh Allen as the author of the Exorcist letter, then it could also be used to rule out David Toschi. If the Exorcist letter and 1978 letter are inextricably linked through DNA and therefore the stamps and envelopes were licked by the same individual, as inferred by Mike Rodelli (from the findings of Criminalist Alan Keel), then by logical extension, if David Toschi was ruled out as the author of the Exorcist letter by palm print, he would also be ruled out as the author of the 1978 letter. 

Deputy Police Chief Clement DeAmicis stated on July 14th 1978, regarding the Exorcist and 1978 letter "We are looking into the authentication of the letters. We have submitted a number of specimens of handwriting. Toschi's is one". Referring to other Zodiac correspondence he continued "We want to know whether they are authentic or whether they are written by somebody we know." Why wouldn't you just compare David Toschi's palm print to the Exorcist letter, as they had apparently done to rule out Arthur Leigh Allen. The San Francisco Police Department stated in 1999 "The Police Department has never made a statement regarding accusations that Toschi faked a Zodiac letter one way or another. We will confirm that not all Zodiac letters are authentic". This final line tells you everything you need to know. The only way they can claim definitively that "not all Zodiac letters are authentic", is if they have confirmed this with DNA. Efforts to harbor DNA from these communications began in the late 1990s - the same time this SFPD statement was released. This lack of transparency from the San Francisco Police Department, the bold claim of ruling out the 1978 letter through DNA (without having confirmed Zodiac DNA), the failure to openly rule out David Toschi using the palm print, and the reluctance to publicly exonerate David Toschi using the 'apparent DNA match between the 1978 letter and Exorcist letter', unfortunately tells you everything. If the San Francisco Police Department have ruled out the 1978 letter through DNA, and not because it's a woman, then it doesn't leave too many other options.

The following is highly speculative and not intended as a solution to the identity of the Zodiac Killer, moreover, an exploration of the January 29th 1974 Exorcist letter in which the author wrote the tantalizing words "Signed, yours truley". Usually the word "signed" would be followed by an author's name, either in full or part. The author of the Exorcist letter stated "Signed, yours truley: He plunged himself into the billowy wave and an echo arose from the suicides grave, titwillo, titwillo, titwillo."
The designer of the Exorcist letter was effectively substituting the signature with a verse from The Mikado's Tit-Willow. In other words, it could suggest his name is present within the verse. The Zodiac Killer (if the author) chose a verse not in keeping with his two previous Mikado selections,  As some day it may happen and A more humane Mikado - both of which had threatening overtones of torture and murder. Whereas, Tit-Willow is about a little tom-tit's last reflective moments before his suicidal plunge into a billowy wave. This may suggest the verse Tit-Willow was chosen for an entirely different reason, particularly in view of the preceding line of "Signed, yours truley", notable on the Dear Boss letter signed by Jack the Ripper and postmarked September 27th 1988, just three years after The Mikado opened at the Savoy Theatre. It should also be noted that William S. Gilbert, responsible for the libretto of The Mikado, released Songs of a Savoyard in 1890 featuring many of the songs from their comic operas. Six songs from The Mikado can be found in Songs of a Savoyard, three of which Zodiac chose - assuming of course, Zodiac was responsible for the January 1974 offering. 

Did the Zodiac Killer embed his name somewhere in his communications as he had promised in his later correspondence? - giving away his forename would certainly not lead to his capture. It has been speculated that the Exorcist letter was a contemplation of suicide on behalf of the author, however, this is hardly in keeping with the threatening overtones of the Bay Area murderer and certainly out of kilter with the foot of the Exorcist letter, which threatens to "do something nasty, which you know I'm capable of doing." It gives the impression that he is threatening to take somebody else's life, not his own. 

There is a strange dichotomy evidenced in the letter, where the author begins by referencing 'The Exorcist' movie (1973) and immediately follows it up by paraphrasing 'Tit-Willow' from 'The Mikado' (1885). 'The Mikado' is often described as the best in British satire, as well as a comedy opera, therefore the word usage of the author describing it as a 'satirical comedy' is unlikely to be accidental. Additionally, the attempted blending of these vastly different productions into one correspondence seems forced, as if chosen for a specific purpose.

The libretto or text was plagiarized from William S. Gilbert. The Exorcist is an  American horror film released in 1973, directed by William Friedkin and adapted for screenplay by William Peter Blatty, based on his 1971 book. The movie divided audiences and critics alike, as it explored the subject of demonic possession, in this case, that of a 12 year old girl played by Linda Denise Blair. This masterpiece of evil still remains one of the most iconic movies in the horror genre to this day. It is fairly evident that the three main protagonists in these productions all have the forename "William". It is also apparent that every verse of Tit-Willow  ends with "Oh, willow, titwillow, titwillow!", in which the name "Will" can be observed three times. The shortened version of William is also present in "billowy". Did the Zodiac Killer choose the Tit-Willow verse after "Signed, yours truley" for no other reason than it contained his name embedded in the text? The next line after "Oh, willow, titwillow, titwillow!" is "Now I feel just as sure as I'm sure that my name".

Bearing in mind the estimated age of the Zodiac given as between 25-45 in 1969, this would make his birth date between 1924 and 1944. So, from a statistical standpoint, I looked at the most popular boys names in the USA in the 1920s, 1930s and 1940s. William was ranked 4th highest in the 1920s with 512,400, 4th highest in the 1930s with 416,646 and 4th highest in the 1940s with 556,399.

In the April 20th 1970 '13 Symbol' cipher, Zodiac stated "This is the Zodiac speaking. By the way have you cracked the last cipher I sent you. My name is...."  The cipher contained three characters twice (A, N, and M) and one character three times (joined O and 8). Therefore, the name "William" gives us a good starting point with two repeating letters.
As an experiment, I looked at the most popular American surnames that could possibly fit the criteria required by the '13 Symbol' cipher and the already inserted "William". Sixteenth on the list was the name Martin, giving us an estimated name of William Martin for the Zodiac Killer. There are many alternative second names that could be applied, but if "William" was the responsible's forename, we would be looking for a 6-letter surname for the confirmed murderer of five.

Unless something extremely important surfaces in the coming weeks, this will be the final installment regarding the 1974 communications, and the distinct possibility that none were authored by the Zodiac Killer - effectively stripping just over three years from his perceived reign of terror. Changing this perception will inevitably generate fierce resistance from the hierarchy of 'Zodiac researchers', who have built a comfortable and reinforced narrative over the last fifty years. This has been my experience with many aspects of the Zodiac case, and the S.L.A letter is just another example of circumnavigating the truth to keep a lie afloat. Faced with tearing a chapter from a prized book, will certainly galvanize the mind into sailing around the facts and ultimately create an alternative reality. It started when Tom Voigt unwittingly announced a new Zodiac letter on his website, labelled the S.L.A letter - mailed on February 14th 1974 and postmarked "unknown". Neither of which are true. Unfortunately however, nearly everybody has embraced this narrative, and will likely carry on believing it, no matter the truth.  

The S.L.A letter was postmarked "U.S. Postal Service, CA 913 PM 3 FEB 1974". This tells you unequivocally that the S.L.A letter was mailed from Los Angeles County, and was likely posted on February 2nd or February 3rd - a day or two before the Patricia Hearst kidnapping by the Symbionese Liberation Army, on February 4th 1974. 

What you will be told by the 'narrative keepers' is that a postmark is not visible on the S.L.A envelope, despite its obvious nth generation appearance. However, what they won't tell you - is they must therefore believe that the two FBI files have been created with malintent. They must believe the FBI files have simply been manufactured - just purposely created to deceive - despite the fact the general public had no access to them. Regardless of the fact that the Zodiac Killer mailed nearly all of his communications from San Francisco, the FBI (according to the doubters of a February 3rd postmark) must have apparently sat round a table and concocted both of these files, including the date and origin of the mailing. The idea that the FBI just chose, or 'plucked from thin air' the February 3rd 1974 date and zip code 913, from Los Angeles County, even though the Zodiac Killer had never mailed a correspondence from this location before, would be patently absurd. The 'narrative keepers' have two choices: If they have a book heavily reliant on a February 14th 1974 mailing, possibly involving a suspect, they can [1] Admit they are wrong and rewrite the chapter, or [2] Kill the messenger and destroy the credibility of the evidence presented. I think you know which number they will choose. This deliberate massaging of the facts to keep a narrative on track rears its ugly head throughout the Zodiac scene, evidently demonstrated in the Robert Graysmith Zodiac book, riddled with contradiction. Many have put faith in a DNA resolution to this case in the near future. But does anybody believe this will result in a mass book burning orgy by renowned Zodiac researchers, finally admitting their passionate fervor was flawed, or another round of circumnavigating reality? For many, the answer is set in stone and nothing will steer them away from the impervious cocoon they have built for themselves. 

I hope that the 'narrative keepers' maintain a February 14th 1974 mailing for the S.L.A letter, because then they have to explain how the Zodiac Killer reappeared after nearly three years of hibernation, to then write a letter about the Symbionese Liberation Army, beginning the correspondence with "Dear" and ending with "a friend", only four days after the actual Symbionese Liberation Army mailed a letter (not publicized) to the Hearst family on February 10th 1974, beginning the correspondence with "Dear" and ending with "A friend". Now that is one hell of a coincidence.  

Then we take a look at the Exorcist letter, mailed on January 29th 1974, which hopefully was not doctored by the FBI.
Kevin Robert Brooks created an extremely credible solution to the Exorcist letter symbols in the form of the words "To Kill". In view of the preceding paragraph, his solution is incredibly convincing: "If I do not see this note in your paper, I will do something nasty, which you know I'm capable of doing. To Kill". Whether this is the answer or not, it is certainly a powerful argument, when we consider the S.L.A letter was entirely geared to giving us the word "Kill". This seemed the only purpose behind the S.L.A communication - as though the letter was designed to give us an answer. The fact that the Exorcist letter symbols were withheld from the January 31st 1974 San Francisco Chronicle publication, may have been the inspiration for the February 3rd 1974 correspondence. It was certainly very fortunate that "Kill" could even be created by the symbols at all, and subsequently highlighted in quotation marks, a matter of days later. 

After the February 10th 1974 Hearst letter, ending with "A friend", another Symbionese Liberation Army communication quickly followed (shown above). Both were intercepted at the Burlingame, California, U.S. Postal Annex and both were addressed to Santa Inez Avenue in Hillsborough. The February 10th letter was postmarked CA 940 - so could have been mailed from Burlingame in San Mateo County, or Santa Clara County. The February 11th letter was postmarked Palo Alto, CA 943. Palo Alto is situated in the northwest region of Santa Clara County. Just shy of two weeks earlier, the Exorcist letter was mailed to the San Francisco Chronicle, postmarked CA 940. The FBI determined that the Exorcist letter was mailed from either San Mateo County or Santa Clara County, just like the two letters above. Probably another coincidence?     
​ 

The Exorcist letter was mailed to the San Francisco Chronicle on January 29th 1974 featuring a 'review' of the 1973 William Friedkin Exorcist movie, a verse from The Mikado's 'Tit-Willow', the usual threat and some curious Asian characters at the foot of the letter, whitewashed from the January 31st San Francisco Chronicle article regarding this communication. Just three days later, a follow-up correspondence, widely labelled the S.L.A letter was mailed, highlighting the word "Kill" at its foot. The Asian characters on the Exorcist letter have been 'decoded' by Zodiac researcher Kevin Robert Brooks to spell "To Kill", opening up the possibility that the designer of the S.L.A letter was immediately responding to the Chronicle's whitewashing of the characters, giving us the solution and thus verifying they were the author of both. However, without being able to convince everybody or anybody of the "To Kill" solution, more is needed in tying these two communications together, along with the May 8th 1974 Citizen card and July 8th 1974 Red Phantom letter. 

The Zodiac Killer had a penchant for the theatrical, appearing in costume at Lake Berryessa on September 27th 1969 and citing Gilbert & Sullivan's Mikado twice in his July 26th 1970 letter. The 1974 Exorcist letter would feature film and theater, the Citizen card expressed consternation at the 1973 Badlands movie and the Red Phantom letter, likewise, may have been referencing a theatrical release of the film El Espectro Rojo or Red Phantom, as detailed by Tom Voigt on Zodiackiller.com. This provides another avenue of inspiration behind the Red Phantom pseudonym chosen by the July 8th 1974 author. It is certainly in keeping with the film and theater angle, heavily laden in the 1974 communications. Tom Voigt articulates that El Espectro Rojo or Red Phantom played at the Port Theater in Mill Valley, Marin County on the 27th and 28th April 1974, just three months prior to the arrival of the Red Phantom letter. The critical part now, is unearthing the inspiration behind the S.L.A letter from a film or theatrical standpoint, and connecting this to a Symbionese Liberation Army member. In a previous article, it has been shown that a Symbionese Liberation Army member typed a letter to the Hearst Family on February 10th 1974 and signed off with "A friend" - a few days earlier, the San Francisco Chronicle S.L.A letter arrived, also signing off with "a friend".  

One possible author of the S.L.A letter (and possibly the Exorcist letter) was Sara Jane Olson (born Kathleen Ann Soliah on January 16, 1947). She was a member of the Symbionese Liberation Army in the 1970s. She grew up in Palmdale, California, the daughter of Norwegian-American parents, Elsie Soliah (née Engstrom) and Palmdale High School English teacher and coach Martin Soliah. Engström, Engstrøm and Engstrom are surnames of Swedish and Norwegian origin. Was she responsible for authoring the S.L.A letter on February 3rd 1974, one or two days before the kidnapping of Patricia Hearst?

To examine this possibility we have to examine her background. The S.L.A letter was postmarked "U.S. Postal Service, CA 913 PM 3 FEB 1974". Kathleen Ann Soliah was brought up in Palmdale, Los Angeles County, California, often frequenting the nearby census-designated area of Agua Dulce. In fact, Agua Dulce was the commuter route from Palmdale to 1466 East 54th Street, Los Angeles -  the site of the deadly shootout between Symbionese Liberation Army members and law enforcement on May 17th 1974, resulting in the deaths of six urban militants. The Symbionese Liberation Army had its main headquarters in San Francisco and Los Angeles. Agua Dulce had a postal zip code of 91390, tying in nicely with the postmark on the February 3rd 1974 S.L.A letter. It is less than five miles from Palmdale. 

To discover the author of the 1974 communications attributed to the Zodiac Killer, we may be looking for somebody familiar with the Zodiac murders and correspondence (particularly with regards to the Exorcist letter), but also, somebody with film and theatrical leanings that may have a strong bearing on the design of the S.L.A letter.

​Kathleen Ann Soliah, after leaving high school, studied acting at nearby Antelope Valley College in Lancaster, California, near Palmdale. She then moved to study theater at the University of California at Santa Barbara, where she met her boyfriend and future Symbionese Liberation Army member, James Kilgore. After graduating in 1969 her radicalization intensified during future years in the Bay Area, eventually becoming friends with the notorious Angela Atwood. This is where a blend of her theatrical leanings, Norwegian-American heritage and a passion for writing may have come into play.

S.L.A  member and boyfriend of Kathleen Ann Soliah, James Kilgore, was ultimately jailed in 2002 for his participation in the April 21st 1975 Crocker National Bank robbery that resulted in the murder of bank customer Myrna Lee Opsahl. “I accept full responsibility for my actions on that day,” said Kilgore, a former San Rafael High School honors student and one-time economics major who became an SLA bomb maker and eventually a professor at the University of Cape Town" ReligionNewsBlog. The July 8th 1974 'Red Phantom' letter was mailed from San Rafael, Marin County, and the May 8th 1974 'Badlands' letter was mailed from Alameda County, where the County Coroner's Office received Symbionese Liberation Army threats after the 1973 murder of Marcus Foster. Espectro Rojo or Red Phantom played at the Port Theater in Mill Valley, Marin County.      

When looking for the inspiration behind the S.L.A letter and "Old Norse", keeping in line with the theatrical influences of the Exorcist letter only days earlier, I looked for a link to the theater in the S.L.A letter too. Whoever designed the Exorcist letter, mimicked the July 26th 1970 Mikado letter mailed by Zodiac. The Mikado is a two part comic opera by Gilbert and Sullivan, which opened to the paying public on March 14th 1885, and was hugely successful, running for 672 performances at the Savoy Theatre in London. Hedda Gabler is a play written by Norwegian playwright Henrik Ibsen. Ibsen was present at the world premiere, which took place on  January 31st 1891 at the Residenztheater in Munich. It is recognized as a classic of realism, nineteenth century theater, and world drama. The title character, Hedda, is considered one of the great dramatic roles in theater.

Symbionese Liberation Army member, Angela DeAngelis "General Gelina" Atwood died in the Los Angeles shootout on May 17th 1974. A year earlier "Kathleen Ann Soliah worked as a cocktail waitress in San Francisco and took small acting roles. She befriended Angela Atwood, the daughter of a New Jersey Teamsters boss who, like Soliah, had grown up in a middle-class home before coming to Berkeley. Atwood, who appeared with Soliah in "Hedda Gabler," helped her friend get a job at the Great Electric Underground, an upscale restaurant in the Bank of America world headquarters". link.

​If Kathleen Ann Soliah authored the February 3rd 1974 S.L.A letter referencing her Norwegian heritage of "Old Norse" and signing off with "a friend", then she was likely the author of the February 10th 1974 S.L.A Hearst letter, again signing off with "A friend". ​Her role in the Norwegian Hedda Gabler theater production would be an influence she carried forward, when we consider the presence of "Old Norse" in the February 3rd 1974 communication. The premiere of Hedda Gabbler opened on January 31st - the same day in history that the San Francisco Chronicle featured the arrival of the Exorcist letter. 

"At this period of Ibsen's youth, Norway experienced a nationalist awakening. The new literary generation, after 400 years of Danish rule, sought to revive the glories of Norwegian history and medieval literature. The middle ages were glorified as well because the romantic movement was in full swing throughout Europe. Thus, when Ole Bull, the great violinist, founded a norse theater at Bergen, the project met with enthusiastic approval from all the youthful idealists eager to subvert the influence of Danish culture.  Encouraged by the success of Ole Bull’s Norse theater in Bergen, enthusiasts of nationalist poetry in the capital also founded a new theater in direct competition with the conservative, Danish-influenced Christiania Theater. Asked to direct this new venture, Ibsen’s promised salary was twice the amount he received at Bergen, about six hundred specie dollars  The problems of Ibsen’s social dramas are consistent throughout all his works. Georg Brandes, a contemporary critic, said of Ibsen, as early as the 1860s, that “his progress from one work to the other is not due to a rich variety of themes and ideas, but on the contrary to a perpetual scrutiny of the same general questions, regarded from different points of view.”
Hedda Gabler, with its emphasis on individual psychology, is a close scrutiny of a woman like Nora Helmer or Mrs. Alving, who searches for personal meaning in a society which denies freedom of expression". link.

The Det norske Theater is a former theater in Bergen, Norway, and regarded as the first pure Norwegian stage theatre. It opened in 1850 by primus motor, violinist Ole Bull, and closed in 1863, after a bankruptcy. Norwegian (norsk) is a North Germanic language spoken mainly in Norway, where it is the official language. Along with Swedish and Danish, Norwegian forms a dialect continuum of more or less mutually intelligible local and regional varieties, and some Norwegian and Swedish dialects, in particular, are very close. These Scandinavian languages, together with Faroese and Icelandic as well as some extinct languages, constitute the North Germanic languages. Faroese and Icelandic are hardly mutually intelligible with Norwegian in their spoken form because continental Scandinavian has diverged from them. While the two Germanic languages with the greatest numbers of speakers, English and German, have close similarities with Norwegian, neither is mutually intelligible with it. Norwegian is a descendant of Old Norse, the common language of the Germanic peoples living in Scandinavia during the Viking Era. Wikipedia.

The S.L.A letter was postmarked - and likely mailed the day before the kidnapping of Patricia Campbell Hearst. The envelope bore the postmark "U.S. Postal Service, CA 913 PM 3 FEB 1974." Considering the February 3rd 1974 letter referred to the Symbionese Liberation Army and the brazen kidnapping of Hearst followed the next day, there is valid case for believing this urban militant group was responsible for the mailing of the S.L.A  letter. But could they have been responsible for the Exorcist letter too? On January 29th 1974 a communication, dubbed the Exorcist letter, arrived at the offices of the San Francisco Chronicle. It featured a critique of the  William Friedkin movie 'The Exorcist', followed by a sprinkling of The Mikado's Tit-Willow, the usual threat to print in paper, a set of Asian-style characters and finally the author signing off with Me-37 SFPD-0. However, the San Francisco Chronicle whitewashed the strange characters near the base of the letter. The Zodiac Killer hadn't written for nearly three years, so this may have been done to weed out any future hoaxers. If the author of the Exorcist letter, which was believed to be the Zodiac Killer, was to mail any future correspondence, he could use the contents whitewashed by the Chronicle to confirm he was the author of the January 29th 1974 communication. This had been done before, when "by knife" written on Bryan Hartnell's car door was withheld from publication after the Lake Berryessa attack on September 27th 1969.  

On January 31st, in an article entitled 'Zodiac Mystery Letter-the First Since 1971', the San Francisco Chronicle presented the Exorcist letter like so. Only two or three days had elapsed, when the S.L.A letter was also mailed to the Chronicle. But had the author of the February 3rd 1974 letter revealed something about the Exorcist letter known only to them and the police? Had the author of the S.L.A letter effectively decoded the Exorcist letter characters for them, but they just didn't realize? 

Just before the author signs off with "a friend" on the S.L.A letter, he highlights the word "Kill" at the foot of the letter, referencing Old Norse. In the identical position at the foot of the Exorcist letter the author highlights the strange characters in bold marker, before signing off with Me-37. Was the author of the S.L.A letter telling us that the word "Kill" could be decoded in the Exorcist letter characters, thereby confirming they were the author of both? The author of the S.L.A letter would not only have to know that characters existed at the foot of the Exorcist letter, because the San Francisco Chronicle had whitewashed them, but also know that they could possibly feature the word "Kill". Could the author of the S.L.A letter, if different from the author of the Exorcist letter, accidentally place the word "Kill" in the same position through two letters, and highlight them both in bold writing and quotation marks to signify their importance? 

The San Francisco Chronicle, along with law enforcement seemingly didn't make the connection, because it wasn't until a few years ago that Zodiac researcher Kevin Robert Brooks offered up a possible solution to the Asian-style characters. When rearranged they were the perfect continuation to the author's preceding paragraph.   

The Exorcist letter would now read "If I do not see this note in your paper, I will do something nasty, which you know I'm capable of doing. To Kill."
Was this the focus behind the entire S.L.A letter, using the Symbionese Liberation Army and "sla" as a precursor to providing the word "Kill" to the San Francisco Chronicle and law enforcement, and therefore verifying they were also responsible for the Exorcist letter? It seemed very fortunate that the word "Kill" in quotation marks was able to be formed by the Asian-style characters of the Exorcist letter, especially considering it was completely whitewashed from publication in the Chronicle.

If the Symbionese Liberation Army were responsible for the February 3rd 1974 S.L.A letter, then what are the chances they created the Exorcist letter too? - fashioned by weaving together traits of old Zodiac Killer letters such as the July 31st 1969 trinity and the Little List letter of July 26th 1970. Or did the Zodiac Killer simply strike gold, writing a letter about the ​Symbionese Liberation Army just one day before Patricia Hearst's kidnapping? 

There is another intriguing possibility albeit without foundation. The Zodiac Killer stopped his letter writing sometime in 1971, with his campaign of terror having probably run its course. What are the chances he pursued different avenues in life, before joining the Symbionese Liberation Army, or becoming affiliated with them in some capacity by the turn of 1974. He then fires off a quartet of diluted Zodiac letters under the umbrella of his new found affiliation. The Symbionese Liberation Army's notable year was 1974, responsible for the Patricia Hearst kidnapping, the raid on the Hibernia Bank and the May 17th deadly shootout in Los Angeles, where six members were shot or burnt to death at 1466 East 54th Street after a standoff with the Los Angeles Police Department. The third letter of the quartet was the 'Badlands' card stating "In light of recent events, this kind of murder-glorification can only be deplorable at best (not that glorification of violence was ever justifiable)", mailed one week before the shootout. Subsequent to the shootout only one more communication would arrive in 1974  - the Red Phantom letter of July 8th 1974 - then radio silence. No correspondence subsequent to 1974 would ever be attributed as genuine Zodiac material. 

The Zodiac Killer wrote copious communications to the newspapers throughout 1969 and 1970, finally ceasing sometime in 1971. It would be nearly a three year hiatus, when suddenly four communications in approximately five months landed at the doorstep of the San Francisco Chronicle. Is it reasonable to assume that the Zodiac Killer just reappeared in 1974 for his encore performance, or something or someone else was responsible for the four correspondences that year? Who, in San Francisco appeared in 1973, ran through 1974, and effectively disappeared by 1975? - the Symbionese Liberation Army is high on that list. "The United Federated Forces of the Symbionese Liberation Army (SLA) was an American left-wing militant organization active between 1973 and 1975 that considered itself a vanguard army. The group committed bank robberies, two murders, and other acts of violence". Wikipedia.  In the previous article it was shown that the S.L.A letter was postmarked February 3rd 1974, not February 14th 1974 as widely touted. This changes the whole story surrounding this letter - now mailed one or two days before the kidnapping of Patty Hearst. Bearing in mind its contents, it's either an amazing stroke of good fortune for the Zodiac Killer, or it was most likely mailed by a member of the Symbionese Liberation Army, knowing that Patty Hearst was soon to be kidnapped from Berkeley, California.   

Operating out of San Francisco and Los Angeles, the members of the S.L.A would have certainly been aware of the Zodiac Killer - and in someway mirrored his form of domestic terrorism. 

"It wasn't until January 10, 1974 that Oakland Police found their first clues. Two men arrested during a gunfight with police in Concord had a truck full of Symbionese Liberation Army literature. Later that day in Concord, a house torched by arson was also full of SLA literature, a stockpile of weapons and two pipe-bombs. The police found a letter titled “The August Seventh Movement,” a group that claimed responsibility for shooting down two Oakland officers in a helicopter by sniper as well as a communique targeting state prison officials and their wives with death by cyanide. In November 1973, Superintendent Marcus Foster (the first black superintendent in the city) of the Oakland School Administration was shot and killed. Deputy Superintendent Robert Blackburn was seriously wounded. The attackers used bullets whose core had been removed and replaced with cyanide crystals. Letters and calls were made to the San Francisco Chronicle, the Alameda County Coroner's Office, and a Berkeley radio station by the Symbionese Liberation Army", Ghoulifornia.

The Symbionese Liberation Army, not only wrote threatening letters to the San Francisco Chronicle, but in similar fashion to the 'Phone call to Melvin Belli' on the Jim Dunbar KGO-TV show, the S.L.A  mailed a cut-and-paste lettered correspondence to KGO-TV. Therefore, isn't it very likely a militant group, operating between 1973 and 1975, who wrote letters to the San Francisco Chronicle, would likely be responsible for the S.L.A letter mailed one day before Patricia Hearst's kidnapping. Or is it more likely that the Zodiac Killer just resurfaced after nearly three years?

On May 8th 1974, twenty-three days after the April 15th 1974 Hibernia Bank Robbery,  the 'Badlands' or 'Citizen Card' was mailed to the San Francisco Chronicle from Alameda County, stating "In 1959 most people were killing time. Kit + Holly were killing people." In light of recent events, this kind of murder-glorification can only be deplorable at best (not that glorification of violence was ever justifiable) why don't you show some concern for public sensibilities + cut the ad?  A citizen." It too ended with a rather benign 'signature', similar to "a friend" on the S.L.A letter, and may have been mailed to mock the authorities, flavored with insincerity. 

S.L.A  member James Kilgore was ultimately jailed in 2002 for his participation in the April 21st 1975 Crocker National Bank robbery that resulted in the murder of bank customer Myrna Lee Opsahl. “I accept full responsibility for my actions on that day,” said Kilgore, a former San Rafael High School honors student and one-time economics major who became an SLA bomb maker and eventually a professor at the University of Cape Town" ReligionNewsBlog. The July 8th 1974 'Red Phantom' letter was mailed from San Rafael, and the May 8th 1974 'Badlands' letter was mailed from Alameda County, where the County Coroner's Office received threats after the 1973 murder of Marcus Foster. The January 29th 1974 'Exorcist' letter was mailed from either San Mateo or Santa Clara County, completing a list of communications mailed from areas the Zodiac Killer had never previously dispatched his correspondence from.  

Mike Rodelli, avid Zodiac researcher and author of the book 'The Inconceivable Double Life of a Notorious Serial Killer-The Hunt for Zodiac,' examined his suspect Kjell Qvale. It is a thorough and comprehensive analysis of every aspect of the Zodiac crimes from the perspective of his suspect, as well as a valuable resource on the case as a whole.

Mike Rodelli considered the wording on the S.L.A letter pertinent to his suspect from a Scandinavian perspective. The S.L.A letter read "Dear Mr Editor,   Did you know that the initials SLAY (Symbionese Liberation Army) spell "sla", an old Norse word meaning "kill". a friend." Kjell Qvale was a Norwegian-American business executive and was one of the key figures in the creation of the Jensen-Healey. He became the first distributor for Jaguar on the Pacific West Coast.

The author of the S.L.A letter by referencing "sla" and "old Norse" was certainly indicating they may have had a Scandinavian connection, although stating "sla" meant "kill" rather than "strike" may have suggested a loose connection through family. Here is an English-Old Norse Dictionary. Sara Jane Olson (born Kathleen Ann Soliah on January 16, 1947) was a member of the Symbionese Liberation Army in the 1970s. She grew up in Palmdale, California, the daughter of Norwegian-American parents, Elsie Soliah (née Engstrom) and Palmdale High School English teacher and coach Martin Soliah. Engström, Engstrøm and Engstrom are surnames of Swedish and Norwegian origin. Was she responsible for authoring the S.L.A letter on February 3rd 1974, one or two days before the kidnapping of Patricia Hearst, which she most likely had knowledge of?

"Kathleen Soliah was born in Fargo, North Dakota, while her family were living in Barnesville, Minnesota. When she was eight, her conservative Lutheran family relocated to Southern California. After graduating from the University of California, Santa Barbara, Soliah moved to Berkeley, California, with her boyfriend, James Kilgore.
On April 21, 1975, SLA members robbed the Crocker National Bank in Carmichael, California, in the process killing 42-year-old Myrna Opsahl, a mother of four depositing money for her church. Patty Hearst, who was switch getaway driver during the crime, provided the original information that led the police to implicate the SLA in the robbery and murder; she also stated that Soliah was one of the actual robbers. According to Hearst, Soliah also kicked a pregnant teller in the abdomen, leading to a miscarriage. Several rounds of 9 mm ammunition spilled on the floor and found in Opsahl's body during the robbery bore manufacturing marks that matched that of ammunition loaded in a 9 mm Browning Hi-Power semi-automatic pistol found by police in Soliah's bedroom dresser drawer at the SLA safehouse on Precita Avenue in San Francisco. In 2002, new forensics technology allowed police to link these shells definitively to those found at Crocker Bank prior to charging the former members of SLA, including Soliah, with the crime. Prosecutor Michael Latin said that Soliah was tied to the crime through fingerprints, a palm print, and handwriting evidence. The palm print was found on a garage door from a garage in which the SLA kept a getaway car". Wikipedia.

​The date the S.L.A letter was mailed changes the whole concept of what we can infer from its contents. On February 14th 1974 the Zodiac Killer is simply latching onto the publicity generated by the kidnapping of Patricia Hearst on February 4th 1974, but on February 3rd 1974 that whole dynamic changes. It now sheds much doubt on the Zodiac Killer being responsible for the S.L.A letter and a lot more besides.  

​S.L.A LETTER NOT ZODIAC - AND HERE IS THE FBI FILE TO PROVE IT

The Exorcist letter bore the postmark 'U.S. Postal Service CA 940 AM 29 Jan', listed in the FBI files as documents Qc62 and Qc63 with a lab number of D-740208094. The following month, in the February of 1974, the S.L.A. (Symbionese Liberation Army) letter arrived at the San Francisco Chronicle. This letter has been ascribed the date of February 14th 1974 on all major websites - and because it followed the Exorcist letter, it is listed in the FBI files as documents Qc64 and Qc65 (envelope and letter) with a lab number of D-740304063. The S.L.A letter stated "Dear Mr Editor, Did you know that the initials SLAY spell "sla", an old Norse word meaning "kill". a friend." The following analysis detailed below is my opinion only, and should not be regarded as fact. After reading this you can obviously come to your own conclusions.

In the FBI file below, it states "Enclosed for the Bureau is one photocopy and one xerox copy of letter and envelope received 2/26/74 from Inspector (redacted) Homicide Detail, San Francisco Police Department. Enclosed for Sacramento is one xerox copy of same letter. For the information of the Bureau, on 2/20/74, Inspector (redacted) advised that on 2/14/74 the enclosed letter was received by the San Francisco Chronicle and (redacted), reporter for the San Francisco Chronicle brought the letter to (redacted) as a possible Zodiac letter. (Redacted) thereafter turned the letter over to (redacted) questioned document examiner, United States Postal Office, San Francisco. Mr (redacted) has advised (redacted) that he feels the letter is a Zodiac letter".

I don't believe this letter is from the Zodiac Killer - it was likely mailed by the Symbionese Liberation Army, or one of their members. In fact, it pours huge doubt on the January 29th 1974 Exorcist letter as being mailed by the Bay Area murderer , rather somebody masquerading as the Zodiac Killer - and here's why. 

What the above document doesn't tell you - is when the S.L.A letter was mailed or postmarked.
The above document read "that on 2/14/74 the enclosed letter was received by the San Francisco Chronicle." Received is not mailed. If we travel a little further in the FBI files we can find more information on the S.L.A letter and envelope, listed under Qc64 and Qc65, as circled in red on the above document.
The FBI files state on more than one occasion:
Qc64 Photocopy of envelope postmarked "U.S. Postal Service, CA 913 PM 3 FEB 1974", bearing the hand printed address "Editor San Francisco Chronicle San Francisco, California".
Qc65 Accompanying photocopy of sheet of paper bearing the hand printed message beginning "Dear Mr. Editor, Did you know that the....."     

It is believed that the Zodiac Killer by mailing the S.L.A letter, was piggybacking the media exposure regarding the kidnapping of Patricia Campbell Hearst, granddaughter of American publishing magnate William Randolph Hearst. "On February 4, 1974, 19-year-old Hearst was kidnapped from her Berkeley, California, apartment. She was beaten and lost consciousness during the abduction. Shots were fired from a machine gun during the incident. An urban guerrilla group called the Symbionese Liberation Army (SLA) claimed responsibility for the abduction". Wikipedia.
​
According to the FBI files above, the S.L.A letter was mailed on or before February 3rd 1974 (postmarked 3 FEB 1974).
Therefore, it was likely mailed one day before the Symbionese Liberation Army kidnapping of Patty Hearst. This means one of four things:
[1] The Zodiac Killer was a member of the S.LA. and was involved in the kidnapping plot. 
[2] The Zodiac Killer didn't belong to the S.L.A, but somehow knew of their plans to kidnap Patty Hearst.​
[3] The Zodiac Killer just got extremely lucky, writing "Dear Mr Editor, Did you know that the initials SLAY spell "sla", an old Norse word meaning "kill". a friend", then mailing the letter on February 3rd 1974, just one day before Patty Hearst was kidnapped by the Symbionese Liberation Army​. In other words, it was sheer coincidence. Or,
[4] The letter was written by the Symbionese Liberation Army and had nothing to do with Zodiac.

If this letter was mailed on February 3rd 1974, the day before the kidnapping, then it is highly likely it was mailed by the American left-wing militant organization ​themselves. Coming just five days after the January 29th 1974 Exorcist letter, in which Kevin Robert Brooks decoded the Asian characters to spell "To Kill", it is yet another amazing coincidence that the author of the S.L.A letter would highlight the word "Kill".   

The emphasis on the word "Kill" at the foot of both letters, within days of one another, leading me to believe they are connected. If the S.LA. letter was penned by the militant Symbionese Liberation Army on or before February 3rd 1974, then a good case can be argued, that they were responsible for the Exorcist letter too. 
​

​S.L.A LETTER NOT ZODIAC - AND HERE IS THE FBI FILE TO PROVE IT

The Exorcist letter has recently come under the spotlight regarding its authenticity as a Zodiac communication, but regardless, we will examine it in context to previous correspondence from the Bay Area murderer and hopefully show that the entire letter is designed around the Gilbert & Sullivan comedic opera 'The Mikado', in particular Ko-Ko the Lord High Executioner. The Zodiac Killer had now seemingly dropped his long-held pseudonym after a three year hiatus and had reemerged, vowing to continue his campaign of murder under a new guise.    

The Zodiac Killer had previously used two musical numbers from The Mikado when he mailed the Little List letter on July 26th 1970. The first was 'A More Humane Mikado', followed by 'As Some Day It May Happen', featuring Ko-Ko, the Lord High Executioner.​
This was noted in the San Francisco Chronicle on October 12th 1970, just 15 days prior to the mailing of the 'Halloween' card: "It was immediately apparent that Zodiac had plagiarized several stanzas from an aria in the Gilbert and Sullivan operetta 'The Mikado'. It is the entrance aria of Ko-Ko, the Lord High Executioner. A quiet search of 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."

The text on the Exorcist letter is split into three sections: [1] The introduction referring to the recently released Exorcist movie, and featured in a newspaper article by reporter Paul Avery, [2] The latest Zodiac pseudonym disguised under the heading of 'Yours truley', and [3] The customary threat promising more victims if his "note" is not published.

There is little doubt that the Zodiac Killer (now Lord High Executioner) is describing the William Friedkin movie 'The Exorcist' in terms of 'The Mikado'. The Gilbert & Sullivan play is often described as a comedic opera of political satire, so the author choosing the words "I saw and think "The Exorcist" was the best satirical comedy that I have ever seen" is certainly not by accident. However, it is the introduction of "I saw and think" that may carry more meaning than initially thought.
​
'As Some Day It May Happen' featured heavily in the July 26th 1970 letter. It was spoken by Ko-Ko, the Lord High Executioner, with the word "think" appearing four times during this act, including the introduction :
[1] "Gentlemen, I'm much touched by this reception. I can only trust that by strict attention to duty I shall ensure a continuance of those favours which it will ever be my study to deserve. If I should ever be called upon to act professionally, I am happy to think that there will be no difficulty in finding plenty of people whose loss will be a distinct gain to society at large". [2] and [3] "And who doesn't think she dances, but would rather like to try; And that singular anomaly, the lady novelist — I don't think she'd be missed — I'm sure she'd not be missed". 
[4] "He's got her on the list — he's got her on the list; And I don't think she'll be missed — I'm sure she'll not be missed".

Was the Zodiac Killer reprising his performance of the Little List letter and using the introduction of "I saw and think" under the guise of Ko-Ko, the Lord High Executioner?  This argument may be bolstered, when he immediately follows this up by signing his new pseudonym in the form of another Ko-Ko, Lord High Executioner verse from 'On A Tree By A River' featuring tit-willow. The author is simply saying "Signed, yours truley: The Lord High Executioner." 

The third section of text on the 'Exorcist' letter is uncannily similar to the first letters mailed by the Zodiac Killer on July 31st 1969. The 'Exorcist' letter was mailed to the San Francisco Chronicle, so we will take a look at the July 31st 1969 letter mailed to the same paper. This is what the killer signed off with: "I want you to print this cipher on the front page of your paper. In this cipher is my idenity. If you do not print this cipher by the afternoon of Fry.1st of Aug 69, I will go on a kill ram-Page Fry. night. I will cruse around all weekend killing lone people in the night then move on to kill again, until I end up with a dozen people over the weekend." It begins with a demand to print his material in the paper, and finishes with the threat "to kill" again if his instructions are not followed, exactly like the Exorcist letter. 

The 'Exorcist' letter symbols were decoded by Kevin Robert Brooks to spell the words "To Kill", which although not proven, makes perfect sense with respect to the July 31st 1969 letters, and in keeping with the Lord High Executioner's list of people who will not be missed. The Mikado style symbolism at the foot of the Exorcist letter threatening "To Kill" again, lending credence to the notion the Zodiac Killer is now operating under the pseudonym of a Japanese High Executioner. 

The answer that has always eluded people - is did the Zodiac Killer begin his murders and letter writing in Riverside, before resuming his campaign of terror in the Bay Area? The Zodiac Killer communications began on July 31st 1969, and presumably ceased with the last confirmed correspondence on January 29th 1974. We have shown the similarity of threats exhibited by the Exorcist letter and the trinity of July 31st 1969 letters, regarding his promise "to kill" if his cipher or "Tit-willow" communications were not published. The 408 cipher was split into three parts (similar to the Exorcist letter) containing 8 lines of text, thereby 24 lines in total. The verse Tit-willow was split identically to the 408 cipher, three verses of 8 lines. The three Bates letters were mailed to Joseph Bates, the Riverside Press Enterprise and Riverside Police, and once again contained double postage like much of the Zodiac correspondence, with each containing just 8 words: "Bates/She had to die there will be more".   

The Mikado influence is present in all three sections of the Exorcist letter (including the Asian style characters) in a reinvention of the July 26th 1970 Little List letter. Was the Exorcist letter a hoaxer operating under the guise of the Zodiac Killer, plagiarizing the Gilbert & Sullivan opera once again and convincing us the threat was still alive in the Bay Area after nearly five years, or was the executioner at Lake Berryessa on September 27th 1969 biding his time, before extinguishing the Zodiac Killer once and for all?

Paul Avery, a reporter at the San Francisco Chronicle, covered many of the Zodiac stories during his reign of terror, and became the focus of the murderer's attention when the Zodiac Killer mailed the 'Halloween' card to the San Francisco Chronicle newspaper on October 27th 1970. The murderer responded to an article published on November 16th 1970 by Paul Avery, linking him to the Riverside murder of Cheri Jo Bates on October 30th 1966. This would be followed nearly three years later, when the 'Exorcist' letter was mailed on January 29th 1974, closely followed by the 'SLA' letter on February 14th 1974, regarding the Symbionese Liberation Army kidnapping of  Patty Hearst, a media heiress, on February 4th 1974.
"Paul Avery covered the Hearst case until the newspaper heiress-turned-bank robber was arrested in September 1975. Avery then holed up on his houseboat at Gate 5 in Sausalito with Boston writer Vin McLellan to write The Voices of Guns, a book on the SLA and the Hearst kidnapping." Wikipedia.

The 'Exorcist' letter has recently courted new attention with the publication of Mike Rodelli's new book 'The Hunt for Zodiac: The Inconceivable Double Life of a Notorious Serial Killer', pouring some doubt on the authenticity of this communication.
This letter, once again, appeared another response to a Paul Avery newspaper article, featuring the recently released Exorcist movie, an American horror film released in 1973, directed by William Friedkin and adapted for screenplay by William Peter Blatty, based on his 1971 book. The San Francisco Chronicle article entitled 'Weird Goings on at the Movies,' was published on January 11th 1974 and detailed the audience reaction to what they had just experienced. The opening lines of the article are extremely interesting when we consider the opening lines of the January 29th 1974 'Exorcist' letter, only 18 days later.     

The article began "If these crowds queuing up three times a night for "The Exorcist" prove anything, it's that a lot of people are willing to go to a lot of trouble to get their wits scared out of them.
Since the day after Christmas, some 60,000 persons have endured a harsh winter's elements standing in lines - sometimes for as long as two hours - to see the see the current cinema rage playing at the Northpoint Theater near Fisherman's Wharf.
It is an experience that produces reactions ranging from vomiting to fainting, to one apparently jaded patron's demand for his money back because it was about as scary as Snow White". 

The author of the 'Exorcist' letter apparently concurred with this disgruntled patron, beginning the letter with "I saw + think "The Exorcist" was the best satirical comedy that I have ever seen,"
The author also made sure to place "The Exorcist" in quotation marks, just like the article. If this letter was the Zodiac Killer, he would go on to use quotation marks around words in his following two correspondences - something he had never previously done in his communications from 1969 to 1971. 

The middle section of the 'Exorcist' letter is signed yours truley 'Ko-Ko Lord High Executioner' by means of Tit-Willow from The Mikado's On a tree by a river. The same can be said of the 'Little List' letter on July 26th 1970, which also featured Ko-Ko in A more humane Mikado.

Then we travel to the most interesting part of the 'Exorcist' letter at the bottom of the correspondence, and its comparison to the first letters mailed by the Zodiac Killer on July 31st 1969. The 'Exorcist' letter was mailed to the San Francisco Chronicle, so we will take a look at the July 31st 1969 letter mailed to the same paper. This is what the killer signed off with: "I want you to print this cipher on the front page of your paper. In this cipher is my idenity. If you do not print this cipher by the afternoon of Fry.1st of Aug 69, I will go on a kill ram-Page Fry. night. I will cruse around all weekend killing lone people in the night then move on to kill again, until I end up with a dozen people over the weekend." It begins with a demand to print his material in the paper, and finishes with the threat "to kill" again if his instructions are not followed.       

The foot of the 'Exorcist' letter begins with a demand to put this note in the paper, and finishes with a threat you know he is capable of. We know what the killer is capable of - it is "to kill" - as he threatened at the foot of the July 31st 1969 San Francisco Chronicle letter if his demands to print the cipher were not met. Even the decoded cipher rammed home the message "To kill something gives me the most thrilling experience". Therefore, by logical deduction, the strange characters at the foot of the 'Exorcist' letter should read "to kill". Thanks to the great work of Zodiac researcher Kevin Robert Brooks, this is exactly what he showed. Even more importantly, the beginning of each word began with an upper case letter, just like "The Exorcist" - forming the words "To Kill" with significant emphasis on the 'K' of "Kill".

This emphasis would be carried forward into the SLA letter, mailed on February 14th 1974, where he uses quotation marks to highlight the word "kill" once more. The murderer now appears to have slayed his demons, signing off the letter with "a friend" - albeit, a friend you wouldn't invite home for tea and scones with grandma.

His reformation now appeared complete in the May 8th 1974 'Citizen' letter, railing against the publication of advertisements for the "Badlands" movie starring Martin Sheen and Sissy Spacek, and based upon the real life events of spree killers Charles Raymond Starkweather and his girlfriend Caril Ann Fugate.

His final consternation would be reserved for Marc H Spinelli in the July 8th 1974 'Red Phantom' letter, calling for the cancellation of his Count Marco column. The murderer now seemingly devoid of the Zodiac persona after exorcising his demons subsequent to January 29th 1974, along with his inability to spell.

Had the Zodiac Killer returned after an absence of nearly three years, or was the return of the Bay Area murderer a demon that had to be resurrected for the sake of publicity in an ever dwindling case.

Zodiac researcher Mike Rodelli recalled a conversation with Alan Keel, Criminalist at the San Francisco Police Department, San Francisco, California from 1996 to 1999. He stated "In contrast (to earlier communications), Keel analyzes two other letters, one of which is the 1978 forgery, and finds that this letter and one of the 1974 letters are loaded with saliva and cells. He then easily extracts DNA from both of these letters using the more primitive DNA technology of that time and finds that the DNA matches between those two letters, thus proving that one person sent both." 

For these two communications to be matched definitively using DNA, "proving that one person sent both", they must have revealed full DNA profiles, otherwise, a partial DNA profile in one could not have proved conclusive. The DNA tests conducted by the San Francisco Police Department in the late 1990s, indicated that subsequent to 1974, only the January 29th 1974 'Exorcist' letter had been processed and "cells found". There was no mention of the other 1974 letters being processed. Therefore, one could conclude that the two letters discovered to match one another (according to Keel), were the 1974 'Exorcist' letter and the April 24th 1978 letter - and therefore written by the same individual.

The 1978 letter is listed in the report as "not authentic Zodiac letter." If the San Francisco Police Department concluded the 1978 letter was not an authentic Zodiac letter, then the 'Exorcist' letter would not be either. This brings forth some interesting questions.    

Michael Butterfield wrote an article entitled 'Zodiac DNA:The Magic Bullet' on his 'Zodiac Killer Facts' website, stating
"In the late 1990s, San Francisco police obtained DNA from a suspected Zodiac letter, and the DNA did not match Allen’s DNA".. 
The San Francisco Police Department surely wouldn't have used the DNA obtained from the April 24th 1978 letter for comparison, as they themselves had deemed it "not authentic Zodiac correspondence" and it had long been considered questionable material. Therefore, they must have obtained this DNA from another letter they "suspected" was a Zodiac letter, to compare to known suspects. But, if the 'Exorcist' letter (as Mike Rodelli suspects) and the 1978 letter matched in DNA, were written by the same individual, and by association were considered "not authentic Zodiac correspondence", then which "suspected Zodiac letter" did the San Francisco Police Department use to compare to Allen's DNA. 

In the San Francisco Police Department report, the only letters in which they stated "cells found", other than the 'Exorcist' letter, were the July 24th 1970 'Kathleen Johns' letter and July 26th 1970 'Little List' letter. Every correspondence tested prior to July 24th 1970 were labelled 'Envelope processed for DNA - few cells'. The 'Exorcist' letter came under scrutiny, alongside the 1978 letter, when Inspector David Toschi fell under the microscope in 1978 for forging one or both. So, would it be likely the 'Exorcist' or 1978 letter would be chosen by the San Francisco Police Department in the 1990s as a "suspected Zodiac letter" (and for the reasons given above), and used to rule out Arthur Leigh Allen's DNA? They surely would have turned to more credible sources. But they only had two other letters where "cells were found".

In 2002, Dr. Cydne Holt performed a new round of tests on some of the early 1969 Zodiac letters. Having failed to find suitable DNA on these letters (as suggested by the "few cells" findings of the 1990s), it has now come to light that the ABC Primetime documentary scoured the outside of the envelopes and stamps for DNA instead, thereby negating any findings as to the identity of the Zodiac Killer.

But why were they searching for Zodiac DNA, to compare to suspects such as Arthur Leigh Allen and Kjell Qvale, when: 
"in the late 1990s, San Francisco police obtained DNA from a suspected Zodiac letter, and the DNA did not match Allen’s DNA".
The new round of tests performed in 2002, would now suggest that the DNA they found in the 1990s from a "suspected Zodiac letter", was no longer believed to be from Zodiac. 

In 2018 "Vallejo police Detective Terry Poyser, who has worked the Zodiac case for four years, said his agency has submitted two envelopes that contained letters from the Zodiac Killer for a type of advanced DNA analysis that previously had not been available in the case. The department has three letters and two envelopes from the Zodiac, Poyser said. The envelopes each have a double stamp, which Poyser said was a trademark of the Zodiac. They originally were sent to the San Francisco Chronicle and the San Francisco Examiner, he said. The third letter was sent to the Vallejo Times-Herald, but does not have an envelope with it, he said." Sacramento Bee.

However, these are the July 31st 1969 envelopes and stamps already tested by Dr. Cydne Holt in 2002, which failed to produce any viable results. The hope is that more advanced DNA analysis may turn up something new. But what about the "suspected Zodiac letter" from the 1990s with "cells found." Couldn't this be examined using advanced DNA analysis? This letter has apparently already produced a DNA profile to rule out Allen, so why is it being ignored - or is it?

In a poll of 93 people conducted on this site, 85% believe the 'Exorcist' letter to be genuine Zodiac correspondence, whereas, in a poll of 94 people conducted on this site, only 54% believe the 1978 letter to be genuine Zodiac correspondence.
If Mike Rodelli's suspicions are true, then both the 'Exorcist' and 1978  letter are "not authentic Zodiac correspondence". If the San Francisco Police Department have long considered these two communications as not credible, then which "suspected Zodiac letter" was used to rule out Arthur Leigh Allen in the 1990s, and can it be used again for advanced DNA analysis?

We have long been led to believe the 'Exorcist' letter was the last confirmed communication by the Zodiac Killer. If the poll on this site were true of the entire Zodiac community, then 85% of people believe the 'Exorcist' letter to be genuine Zodiac correspondence. If the other 1974 letters were not tested or found to contain DNA (as the SFPD report suggests), then it is extremely likely a full DNA profile exists for the 'Exorcist' letter (shown at the top of this article).

For those who believe the January 29th 1974 'Exorcist' letter to be an authentic mailing from the Zodiac Killer with a full DNA profile, you should be asking "why hasn't this been run through GEDmatch."

I have just finished reading 'The Hunt for Zodiac: The Inconceivable Double Life of a Notorious Serial Killer' by Zodiac researcher Mike Rodelli. While I don't agree with everything in the book, it is an extremely well researched and informative addition to the Zodiac Killer story, even if you don't arrive at the same conclusions on the murderer's identity. For beginners and seasoned veterans alike, it will not disappoint as a comprehensive introduction to the case, as well as a complimentary addition to any existing knowledge you may already have. While fresh in my mind, I would like to explore one important feature of the book, regarding the topic of DNA, which is currently hanging over the case like a dose of skeptical optimism.. 

Mike tackles this problem in extensive detail, particularly with regards to the viability of the DNA tests conducted by Dr. Cydne Holt in the 2002 ABC Primetime documentary, in addition to his discussions with Alan Keel, Criminalist at the San Francisco Police Department, San Francisco, California from 1996 to 1999.

The disputed results of the 2002 'showpiece' are now well documented, however, Mike delves further into the DNA analysis with respect to two later 'Zodiac' letters, namely the 1974 'Exorcist' letter and the subsequent 1978 'I Am Back With You' letter, both mailed after a lengthy silence from the Zodiac Killer - leading some to question their authenticity. 

Mike recalls information of his conversation with Alan Keel: "In contrast (to earlier communications), Keel analyzes two other letters, one of which is the 1978 forgery, and finds that this letter and one of the 1974 letters are loaded with saliva and cells. He then easily extracts DNA from both of these letters using the more primitive DNA technology of that time and finds that the DNA matches between those two letters, thus proving that one person sent both." 

This is a stunning revelation (if correct) when we consider the findings of the San Francisco Police Department laboratory in the 1990s, in which there was a notable absence of saliva/DNA present on the envelopes prior to the 1974 'Exorcist' letter. Would a killer who seemingly didn't lick any of his envelopes or stamps throughout the majority of his letter-writing campaign, now suddenly break that habit in the 1974 and 1978 communications? The SFPD report, shown here, references the April 24th 1978 letter, claiming that the "DNA SAMPLE OBTAINED - NOT AUTHENTIC ZODIAC LETTER".   

This lack of saliva or DNA on the earlier letters may have become more evident, as Dr..Cydne Holt struggled to generate any tangible results from the sealed sections of stamps and envelopes using more advanced forensic DNA testing in 2002, compared to the earlier and more primitive testing undertaken in the 1990s. This apparent dichotomy brings into stark reality the essence of Mike Rodelli's argument.     

The bold statement of "DNA  sample obtained- not authentic Zodiac letter" opens up the proverbial can of worms. On first reading, it gives the impression that they have something to compare it to. How would they know the DNA sample obtained from the 1978 letter was not from Zodiac, if they didn't have Zodiac's DNA? If they had Zodiac's DNA in the 1990's, this wasn't the impression given by the search for Zodiac DNA in the 2002 ABC Primetime documentary.

"DNA  sample obtained- not authentic Zodiac letter" could imply they know the sex of the DNA present on the 1978 letter, and therefore by extension, not the Zodiac Killer (as suggested on many forums). But, it could imply they know the identity of the individual who contributed the DNA to the 1978 letter, and having identified that individual, know they were not the Zodiac Killer. This lack of clarity has led Zodiac researchers to question the transparency of the San Francisco Police Department.     

We know that a partial DNA profile from a letter can exclude suspects, but not definitively identify an individual. Therefore, the apparent (but unconfirmed) revelation of Alan Keel that "DNA matches between" one of the 1974 letters (possibly the 'Exorcist' letter) and 1978 'I Am Back With You' letter, would suggest that full DNA profiles have been obtained for both letters.
​If only a partial DNA profile had been obtained from the 1978 letter (much like the exclusion of suspects) it can only be excluded as matching a profile from the 'Exorcist' letter (if this had a full DNA profile), but not definitively matched to it.
As such, the statement of "DNA matches between those two letters, thus proving that one person sent both", would be indicative of a full DNA profile obtained from both the 1974 and 1978 letters in the 1990s.. 

For those who believe the 'Exorcist' letter to be genuine Zodiac correspondence, then this could imply that a full DNA profile may exist for this letter (or one of the 'lesser' 1974 letters), and consequently the profile of the Zodiac Killer. However, the search for Zodiac's DNA in 2002 negates this premise - unless the San Francisco Police Department knew all along that both the 'Exorcist'/74 letter and 1978 letter were not mailed by the Zodiac Killer. In fact, the Exorcist and April 24th 1978 letters were the only two communications mentioned with regards to the controversy surrounding Inspector David Toschi, who led the investigation for many years. He came under suspicion for forging the 1978 letter, after the San Francisco Chronicle columnist and author, Armistead Maupin, discovered that David Toschi had mailed fictitious fan mail to a series he had written, with the inclusion of the detective.  ​

​Armistead Maupin had first met David Toschi in 1976 while he was writing the 'Tales of the City' series. Wanting to energize the series with a murder mystery element, he contacted San Francisco Chronicle reporter Bob Popp, who then introduced him to David Toschi. The police inspector would make a debut appearance in 'Tales of the City' on September 10th that year, with a character based on his attributes. Further episodes would follow under his real name, as a friend and confidant to Armistead Maupin's fictitious Detective Inspector Henry Tandy. 

Here is an excerpt from the San Francisco Chronicle, published on July 14th 1978 "Police officials are investigating the possibility that Inspector David Toschi forged a Zodiac letter in The Chronicle in 1974 as well as a similar letter the newspaper received earlier this year. Toschi - who said he was interrogated officially last Friday about both letters - has denied writing any letters in the guise of Zodiac, the killer of six who eluded capture by Toschi for nearly nine years before the detective was transferred out of the homicide detail last week.
Deputy Clement DeAmicis, who had recommended the transfer to Chief Charles Gain, confirmed yesterday the probe was being extended".  

The fact that Inspector David Toschi was questioned regarding these two communications, only heightens the mystery surrounding Alan Keel's statement of "the DNA matches between those two letters, thus proving that one person sent both" and the San Francisco Police Department's report concerning the 1978 letter, in which it noted that a "DNA  sample was obtained, but indicated it was not an authentic Zodiac letter".

We don't know for certain that Alan Keel is referring to the 'Exorcist' letter when he stated "one of which is the 1978 forgery, and finds that this letter and one of the 1974 letters are loaded with saliva and cells".  However, since the 'Exorcist' letter for the large part has been widely regarded as the last confirmed correspondence mailed by the Zodiac Killer, as opposed to the other 1974 communications,  it would be the logical correspondence to test for Zodiac Killer DNA  when searching for the Bay Area murderer. Testing the other much more questionable 1974 mailings would not make as much sense - which is probably why the San Francisco Police Department report is blank or omitted next to these communications. 

The 'go to' mailing, when testing for Zodiac DNA from the 1974 letters, would undoubtedly be the 'Exorcist' letter rather than its dubious companions. So, if this was the case, and the statement of Alan Keel were true, then the 'Exorcist' mailing would not be an authentic Zodiac correspondence, and as a result, would quite possibly shrink the Zodiac reign by nearly three years.  

Here we will revisit an article published by the San Francisco Examiner on October 22nd 1969, in which Professor D.C.B. Marsh, president of the American Cryptogram Association laid down a challenge to Zodiac. The words he chose to use in this article may be the bedrock to much of the subsequent Zodiac communications, beginning with the 340 cipher, mailed only seventeen days after the San Francisco Examiner article. Here are the crucial extracts from that article.
'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." It is difficult to believe that Zodiac, an avid reader of the newspapers, could resist such a challenge, particularly as he had promised to reveal his identity in the 408 cipher two months earlier, but failed to do so.  

The key section to note in the challenge by Professor D.C.B. Marsh is: "I invite Zodiac to send The American Cryptogram Association a cipher code, which will truly and honestly include his name."
Seventeen days later, the Zodiac Killer duly obliged with the November 8th 1969 340 cipher. Could this cipher have included the killer's name, but not in the format envisaged by Professor D.C.B. Marsh?
In a previous article entitled 'Zodiac Admitted 340 Not a Real Cipher' we examined the idea that the 340 cipher was inextricably linked to the Zodiac's 'Halloween' card, mailed on October 27th 1970. One can notice that the word "By" is located in each of the four quadrants of the 340 cipher. The author of the cipher also placed the letters F and K adjacent to one another no less than seven times (situated in each quadrant). But of particular interest was the corrected section on the sixth line of the 340 cipher, where the author chose to scrub out a forward facing K and replace it with a backwards K, elevated above the blacked out section.
The Zodiac Killer was known for numerous spelling errors in his communications, so why was it seemingly imperative to correct this one mistake? Was this correction crucial to the interpretation of the cipher, or was he drawing our attention to the letters in this section of the cipher? Are the F and K characters the initials of the Zodiac Killer?
This observation carries little merit on its own, so to bolster any argument for the initials of the Zodiac Killer being present in the 340 cipher, we have to explore the rest of his communications, particularly from around the time of the 'Halloween' card, in which we suggested was his admission that the 340 was unfortunately "no cipher". 
Linking the 'Halloween' card and 340 cipher through a Tim Holt comic book and explaining to us that the solution was "sorry no cipher." left us with the possibility that the 340 cipher was just a collection of puzzles, in which may have contained his name. The Zodiac Killer "wouldn't dare, as he claimed in letters to the newspapers, to reveal his name in the cipher to established cryptogram experts", but he may have given us the abridged version.
We now enter the crucial phase of Zodiac communications, from the '13 Hole' postcard mailed on October 5th 1970, to the 'Exorcist' letter mailed on January 29th 1974. This critical period of four consecutive communications, is probably key to understanding the message the Zodiac Killer was trying to push. That the 340 was "sorry no cipher."      

In the '13 Hole' postcard the Zodiac Killer stated "There are reports city police pig cops are closeing in on me. Fk I'm crackproof. What is the price tag now?"
This section of pasted letters was placed upside down. The question one should be asking is 'what is the purpose behind this'. If its significance had no relevance to the actual postcard, did it have relevance to another communication.
The wording "FK I'm crackproof" could indicate that the killer thought he was immune from capture, however, it could also be a reference to his 340 cipher once again. The word "crackproof" is something that is unable to be cracked.
The 340 cipher would certainly be impervious to cracking, and certainly resistant to the attempts of The American Cryptogram Association had the killer devised a cipher not of conventional understanding, of which Professor D.C.B. Marsh was hoping when he laid down the challenge. The F and K text being flipped on the '13 Hole' postcard reminds one of the flipped K (next to F) on the only corrected portion of the 340 cipher. If FK were the Zodiac Killer's initials, then he certainly could be declaring that he was crackproof. 
​Professor D.C.B. Marsh stated  "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." However, the Zodiac Killer could give his name in the form of initials without any fear of revealing his identity, and without risking his immediate capture. This may have manifested itself when he mailed his following cipher on April 20th 1970, when he opened with the gambit "This is the Zodiac speaking. By the way have you cracked the last cipher I sent you. My name is...."  The code placed underneath was likely an immediate rebuttal to this question. 

All he is probably doing, is stating "My name is FK," and once again telling us he is crackproof, just like the '13 Hole' postcard, which would be mailed five and a half months later. The phrase "FK I'm crackproof" fits perfectly in circular formation within the '13 Symbol' cipher- which itself contains a series of circled 8's. Structured in this fashion, the F and K yet again align, as does the K and M in both the cipher and phrase. 
Continuing with our four consecutive communications from October 5th 1970 onward, we now have the October 27th 1970 'Halloween' card promising to yet again reveal his name: "I feel it in my bones, You ache to know my name, And so I'll clue you in." Again we feel disappointed only to see the word "Boo" on the card inner- but we know the Zodiac Killer isn't going to make this a conventional and straightforward offering. He offers us the phrase "sorry no cipher," but can we find his name or initials within this communication. This is where it gets more difficult, nevertheless, we are aware that within the '13 Hole' postcard he reversed or flipped the text containing "FK I'm crackproof" and he flipped the K (next to the F) on the sixth line of the 340 cipher. So the obvious conclusion, is to look for flipped or reversed text within the 'Halloween' card.  

The only place that F and K exist within one word on the 'Halloween' card, is in the word "knife." either side of the reversed letter N.
If we flipped the reversed N back to its appropriate position, the F and K of "knife" would be reversed yet again.
Now let us turn our attention to the peculiar configuration at the foot of the card inner. It would be extremely satisfying for the 'Halloween' card to read "I feel it in my bones, You ache to know my name, And so I'll clue you in... FK,"- so that is what we will create, by manipulating this card to read whatever we want it to.
The strange symbol, reading it as true as possible, appears like a number 7, followed by four dots and the letter F.
7+4=11=K (followed by F).
Without further ado, we shall move on to the next confirmed Zodiac communication on March 13th 1971, in which the Zodiac stated "This is the Zodiac speaking. Like I have allways said, I am crack proof. If the Blue Meannies are evere going to catch me, they had best get off their fat asses + do something. Because the longer they fiddle + fart around, the more slaves I will collect for my after life. I do have to give them credit for stumbling across my riverside activity, but they are only finding the easy ones, there are a hell of a lot more down there. The reason I'm writing to the Times is this, They don't bury me on the back pages like some of the others."
You will notice that the Zodiac Killer refers to "crackproof" once again, parroting his October 5th 1970 communication five months earlier. However, he doesn't just state he is crackproof, he reminds us that he has always been telling us he is crackproof, and quite possibly we just haven't got the message.

Roll on the January 29th 1974 'Exorcist' letter, signed "yours truley," nearly three years later, giving us our final installment of FK contained within the array of symbols at the foot of the letter. 
On this occasion he mirrors the sixth line of the 340 cipher by elevating the K above the letter F, and to its left. In fact, five characters from the Exorcist letter can be found in and around the corrected sixth line of the 340 cipher, as shown here in a previous article. This was possibly the fourth consecutive communication inferring an FK link and the suggestion that the author was indeed "crackproof."  
Was this a persistent and deliberate attempt to be true to the challenge laid down by The American Cryptogram Association and Professor D.C.B Marsh, by inserting his name (albeit initials) into the 340 cipher and subsequent communications, or just a case that my mind is F@@Ked after six exhausting years of looking for patterns where none exist.

The Zodiac Killer quoted a portion from one of the three stanzas of The Mikado's Tit-Willow, when he mailed the 'Exorcist' letter on January 29th 1974. This may possibly have been the third correspondence, including the 'Halloween' card, where The Mikado was referenced. The Zodiac Killer began with the 'Little List' letter on July 26th 1970, in which he paraphrased 'As some day it may happen' featuring Ko-Ko the Lord High Executioner. In the letter he was effectively quoting the search for future victims as paralleling his agenda throughout the state of California. If we break down the 'Exorcist' letter into its constituent parts, it becomes apparent the correspondence is a further threat towards the citizens of California rather than a declaration of his impending suicide.
If we take a look at the October 27th 1970 'Halloween' card and compare it to his confirmed attacks, only one stands out. On September 27th 1969 Cecelia Shepard and Bryan Hartnell were relaxing by the shores of Lake Berryessa when a man spotted by Cecelia ducked behind a tree to don an executioner's mask and waistline bib. This theatrical entrance in the form of Ko-Ko the Lord High Executioner has long been suggested as an influence on the Zodiac's actions and writings. Here is an extract from the San Francisco Chronicle on October 12th 1970, just 15 days prior to the mailing of the 'Halloween' card:
"It was immediately apparent that Zodiac had plagiarized several stanzas from an aria in the Gilbert and Sullivan operetta 'The Mikado'. It is the entrance aria of Ko-Ko, the Lord High Executioner. A quiet search of 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." 

The 'Halloween' card depicted an eye peering from the knothole of a tree, accompanied by the words 'peek-a-boo you are doomed', implying the impending threat of the Zodiac Killer hiding behind the tree at Lake Berryessa and his ultimate arrival bedecked in an executioner's outfit. If you look up the definition of peek-a-boo in Wikipedia, it quotes "Peekaboo (also spelled peek-a-boo) is a form of play primarily played with an infant. To play, one player hides their face, pops back into the view of the other, and says Peekaboo!, sometimes followed by I see you! There are many variations: for example, where trees are involved, "Hiding behind that tree!" is sometimes added." 
However, Peek-A- Boo was also a character in another version of The Mikado at around the same time as the Gilbert and Sullivan operetta. "In 1888 Jack the Ripper terrorized the Whitechapel district of London. In the same year of somewhat less significance Ed J. Smith wrote a stage parody called The Capitalist; or, The City of Fort Worth. Designed to encourage capital investment in Fort Worth, Texas, and underwritten by local banks and railroad lines, the two act piece features characters named Yankee-Doo, Kokonut, By-Gum and Peek-A-Boo." Here is an image depicting this reference.     

Peep-bo is the English version of peek-a-boo, and has a curious, albeit likely unintentional connection to the Lake Berryessa murder of Cecelia Shepard, in the nursery rhyme Little Bo-Peep.
​"The earliest record of this rhyme is in a manuscript of around 1805, which contains only the first verse. There are references to a children's game called "bo-peep", from the 16th century, including one in Shakespeare's King Lear (Act I Scene iv), for which "bo-peep" is thought to refer to the children's game of peek-a-boo, but no evidence that the rhyme existed earlier than the 18th century. The additional verses are first recorded in the earliest printed version in a version of Gammer Gurton's Garland or The Nursery Parnassus in 1810". Wikipedia.
Peep-bo was one of the three little maids from The Mikado: "Three little maids from school are we, pert as a school-girl well can be, filled to the brim with girlish glee, three little maids from school." 

Three young girls from Pacific Union College would feature in the Zodiac story of Lake Berryessa that day, when describing a suspicious individual roaming the hillsides surrounding the lake- later providing a sketch of the individual. 
Little Bo-Peep was a shepherdess, so its significance to the name of Cecelia Shepard could not be ignored, although likely accidental. "She heaved a sigh and wiped her eye, and over the hillocks went rambling, and tried what she could, as a shepherdess should, to tack each again to its lambkin"
The Riverside murder of Cheri Jo Bates on October 30th 1966 and the subsequent 'Confession' letter held an odd precursor to the events of Lake Berryessa, when it stated "Miss Bates was stupid. She went to the slaughter like a lamb", along with the widely referenced "She squirmed and shook as I choked her, and her lips twitched" connection to the 'Little List' letter.  

​The Zodiac Killer, after mailing his response to the unearthed Riverside connection would then go into hibernation from March 13th 1971 until the arrival of the 'Exorcist' letter nearly three years later on January 29th 1974, leading many to believe the Zodiac Killer was likely incarcerated during this period. 
"Taken from the county jail
By a set of curious chances;
Liberated then on bail,
On my own recognizances;
Wafted by a favouring gale
As one sometimes is in trances,
To a height that few can scale."  Behold the Lord High Executioner Youtube
The Mikado/Act I/Part V
The Lord High Executioner was to return, berating the 1973 film 'The Exorcist,' yet curiously comparing it to the Gilbert and Sullivan's satirical operatic comedy, The Mikado, calling it "the best satirical comedy that I have ever seen."  He then signed his name using the verse of Tit-Willow by Ko-Ko: "He plunged himself into the billowy wave and an echo arose from the suicides grave, titwillo, titwillo, titwillo."
The whole letter was effectively announcing the return of the Lord High Executioner after nearly three years. Here is the 'Exorcist' letter broken down into its constituent parts to reveal its likely meaning.
"I saw and think "The Exorcist" was the best satirical comedy that I have ever seen, even better than The Mikado. Signed, yours truley: The Lord High Executioner. If I do not see this note in your paper, I will do something nasty, which you know I'm capable of doing- To Kill."
Kevin Robert Brooks came up with possibly the best interpretation of the Japanese/Asian symbols at the foot of the letter, befitting of Ko-Ko the Lord High Executioner. The "This is the Zodiac speaking" introduction was apparent by its absence, as well as the Zodiac crosshairs- but the Lord High Executioner was alive and well, and still making threats.