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. 

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.

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?

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.  

The Zodiac Killer teased us with his name on more than one occasion, firstly in the July 31st 1969 San Francisco Chronicle letter where he stated "I want you to print this cipher on the front page of your paper. In this cipher is my idenity." He would follow this up with the 'My Name is...' letter on April 20th 1970 and the 'Halloween' card on October 27th 1970 tempting us with his name again; "I feel it in my bones, You ache to know my name, And so I'll clue you in.." 
​It would appear however, this was never to be the case and we are still no nearer to securing the identity of the Zodiac Killer nearly half a century later. It always seemed strange the Zodiac Killer would interpose the Gilbert and Sullivan Mikado into his correspondence, leading researchers to believe he was a fan of the theater, having quoted three acts of The Mikado in the 'Little List' letter of July 26th 1970 and 'Exorcist' letter of January 29th 1974. But there may be an ulterior motive behind this apparent fascination with Gilbert and Sullivan, in that the killer was using the Mikado to reveal his name, and likely through four mailings rather than the accepted two. We will take a closer look at these four correspondences and the speculative links between them, without claiming this is anything more than coincidence. Let us first look at the 'Exorcist' letter.   

The first thing to notice is its carefully structured appearance, being divided neatly into four sections of text. The curious thing about the correspondence is Zodiac wrote "Signed, yours truley," as though he was about to offer up his name in the third block of writing. He then recited ​Act II -On a tree by a river from The Mikado. It seemed like Zodiac was wasting our time, plucking out random verses from The Mikado, that is until you read verse three of this particular act. It not only contained a reference to 'name', but pointed us towards 'The My Name is...' cipher, mailed on April 20th 1970. Here is verse three.
Now I feel just as sure as I'm sure that my name
Isn't Willow, titwillow, titwillow,
That 'twas blighted affection that made him exclaim
"Oh, willow, titwillow, titwillow!"
And if you remain callous and obdurate, I
Shall perish as he did, and you will know why,
Though I probably shall not exclaim as I die,
"Oh, willow, titwillow, titwillow!"

Was the Zodiac Killer giving us clues to his identity or name, by leading us back to the '13 Symbol' cipher. This observation on its own is meaningless, so we will travel back in time to the 'Little List' letter mailed on July 26th 1970, the supposed only other correspondence to contain references to The Mikado- in fact two. The first section of the 'Little List' letter pulled lines from  'A more humane Mikado', and continued on to extensively recite Gilbert and Sullivan's Mikado Act One Part 5a  'As some day it may happen', performed by Ko-Ko. In the introductory part of the letter, Zodiac simply boasted about how he would torture his slaves in paradise, but he again did something curious, by selecting just one small section of 'A more humane Mikado,' despite it being ten verses in length. The same as he did in the 'Exorcist' letter. He then continued to paraphrase the entirety of 'As some day it may happen'.
The 'Exorcist' letter, we have shown to have tenuous links to the April 20th 1970 'My Name is...' letter, using verse three of 'Tit-Willow'. So let us look at the small section of text Zodiac selected from 'A more humane Mikado.'
The 'Little List' letter read "And all billiard players I shall have them play in a darkened dungen cell with crooked cues + Twisted Shoes."  Why does Zodiac select this small portion. Was this also hinting towards the 'My Name is...' cipher.
When we think of billiard players or billiard balls from the standpoint of America, eight-ball comes to mind, and the circled eights on the '13 Symbol' cipher. 

This is the full verse (right) from 'A more humane Mikado.' It is actually verse eight out of ten, providing us with the numerical link, as did verse three from the 'Exorcist' letter. The Zodiac Killer did state on the 'My Name is...' letter; "PS I hope you have fun trying to figgure out who I killed."​​​
There is however another link from 'A more humane Mikado,' to the alphabetical characters on the '13 Symbol' code mailed by Zodiac.
The Zodiac Killer supplied us with eight alphabetical characters, reading from left to right  A, E, N, K, M, N, A and M.
In the diagram below, key sections of 'A more humane Mikado' are highlighted for comparison to the '13 Symbol' cipher. Seven letters have been highlighted in green and yellow. This is where we must take a bold leap of faith, and consider that the Zodiac Killer chose The Mikado by Gilbert and Sullivan because it simply contained his name, Kim. Nothing more theatrical than that. 

The green highlighted sections on 'A more humane Mikado' in reverse, read KIMNAM. If we believe therefore, that the middle eight represents the letter I on the '13 Symbol' cipher, it reads forward KIMNAM, exactly the same. The remaining letters of the cipher AEN are shown highlighted in yellow. Every letter on the '13 Symbol' cipher is contained within this section of seven letters. 
​The three eights encapsulated his identity, just like the three eights at the foot of the '340' character cipher mailed on November 8th 1969: The Mathematics of the 13 Symbol Cipher. Who said the Magic 8 ball was just for telling fortunes! Additionally, Mikado can be formed using the alphabetical characters on the 20th line of the '340' cipher.
The Zodiac was keen to share with us what he had in store for his slaves in paradise:
"This is the Zodiac speaking. Being that you will not wear some nice buttons, how about wearing some nasty buttons. Or any kind of buttons that you can think up. If you do not wear any type of buttons, I shall (on top of everything else) torture all 13 of my slaves that I have waiting for me in Paradice. Some I shall tie over ant hills and watch them scream + twich and squirm. Others shall have pine splinters driven under their nails + then burned. Others shall be placed in cages + fed salt beef untill they are gorged then I shall listen to their pleass for water and I shall laugh at them. Others will hang by their thumbs + burn in the sun then I will rub them down with deep heat to warm them up. Others I shall skin them alive + let them run around screaming. And all billiard players I shall have them play in a darkened dungen cell with crooked cues + Twisted Shoes. Yes I shall have great fun inflicting the most delicious of pain to my slaves."
The talk of slaves, paradise, pine splinters, dungeons and hanging his 'prisoners' by the thumbs, catapulted me to the 'Halloween' card mailed on October 27th 1970, and the last Mikado installment. The Zodiac Killer placed some wording around the knothole in the tree:"peek a boo you are doomed." Bearing in mind that The Mikado opened to the paying public on March 14th 1885, and was hugely successful, running for 672 performances at the Savoy Theatre in London, a British connection had to be sought. The British term for peek-a-boo is peep-bo, and peep-bo is a character in The Mikado.      

The final confirmed letter mailed by the infamous Zodiac Killer to the San Francisco Chronicle on January 29th 1974, has been commonly referred to as the Exorcist Letter. This sixty one word correspondence appeared to mock the 1973 movie 'The Exorcist', directed by William Friedkin and based on a novel by William Peter Blatty published in 1971, chronicling the demonic possession of a twelve year old girl, Regan MacNeil. William Peter Blatty spent long nights in a secluded Lake Tahoe cabin, crafting images of good and evil, religion, faith and the afterlife, that would eventually go on to make movie history and court its fair share of controversy along the way. 
The letter is short, reminiscent of much of the Zodiac Killer's later contact with authorities, but as well as mentioning the Exorcist movie, the letter, in rather disjointed fashion, breaks into a Mikado recital once again, recalling memories of the Little List Letter mailed three and a half years previously on July 26th 1970. But this time the foreboding 'Tit Willow' seemed contemplatory in this context, possibly marking the end of the Zodiac reign, and to this day, is still often quoted as the murderer's epitaph. The third and final section issued the usual threat of more murders, capped off with Asian style symbols, in the form of a cryptic message. 
Like much of his later correspondence there is little substance here, but we will attempt to delve a little deeper into the Exorcist letter and find any links that may be relevant or otherwise, as to why he wrote the letter in the first place. This is not a theory, just an examination into the reasoning, whereby the Zodiac Killer may have been drawing his inspiration.       

rabbit or hare, apparently gazing up at the wintry scene. One cannot help thinking the Zodiac Killer chose his cards for a reason.
Another interesting connection was noted on viewing the Tom Hanson Zodiac movie from 1971, in that the killer wore a Groucho Marx style nose and glasses in one scene from the movie. View the scene and thread at ZodiacKiller.com.
But this was not the only possible film connection to the Groucho Marx disguise featured on the 1990 Eureka Card.  

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

All that is left to do now is examine the strange symbol at the foot of the Exorcist Letter, but we will leave that for another time.

Waiting in the wings, the Zodiac Killer was not content with a supporting role and yearned to have his name in the spotlight, determined to act out his deep seated desire on a much grander scale - but unlike the theatrical tragedies that had gone before him, this one was to be performed on the very real stage of Northern California, with dark consequences. This analysis probes into the mindset of the Zodiac Killer and his influences as the driving force behind the numerous communications he orchestrated over a period of nearly five years, to narrow down a profession that, above all, takes center stage. It has been noted on countless occasions that the Zodiac Killer had leanings toward the dramatic, His early correspondence included part inference to The Most Dangerous Game, a short story by Richard Connell, published on January 19th 1924, as well as several references to the Gilbert and Sullivan comic opera, The Mikado, first viewed by the paying public on March 14th 1885. The Mikado featured heavily in his 'Little List' letter, mailed to the San Francisco Chronicle on July 26th 1970 and was resurrected in the 'Exorcist' letter, his last confirmed correspondence, mailed on January 29th 1974.

In the counterculture revolution of the 1960s, a new breed of expressionism emerged, in alliance with the already existing forces of cinema and theater that permeated the San Francisco culture and provided the backdrop for a diverse cocktail of literary and visual freedom.​

He claimed in his Bus Bomb letter of November 9th 1969 "The police shall never catch me, because I have been too clever for them.  I look like the description passed out only when I do my thing, the rest of the time I look entirle different. I shall not tell you what my descise consists of when I kill". He also made a grand appearance at Lake Berryessa on September 27th 1969, having purchased, borrowed or crafted a black executioner's hood and a waistline bib, emblazoned with the Zodiac crosshairs - but either way, his entrance was of theatrical proportions.

One thing evident throughout his correspondence, was his use of the word shall, leading to speculation that he may have been of British origin, as the word shall, is infrequently used in American English. However, another option exists. As a member of theater production, his exposure to the word shall would have been far more frequent in the performance of stage plays, particularly in traditional works of English origin, which he would seek to take to the next level when he started crafting his own scripts. Embittered by rejection, he mailed his work to the heart of the American people via the San Francisco Chronicle, seeking literary recognition, but sadly only succeeded in creating a tragedy of epic proportions, while hiding behind a pseudonym and mask of sanity.

The Zodiac Killer mystery retains an unfaltering allure, that has managed to captivate a worldwide audience for more than four decades. When people become entranced with the case, there are many times upon reviewing the postcards, ciphers and wording, that the breath of the killer can almost be felt for a brief moment, when you spot something you think is significant, before it is cruelly snatched away. But it does not stop you trying, in essence to close the book on years of torment for the victims families and friends, which often has unfortunately become lost in the midst of this tragic affair.
Many suspects have been touted as the infamous Zodiac Killer, and most have been effectively eliminated from ongoing scrutiny. However, recently another name has emerged, that of Donald Lee Bujok, promoted from previous obscurity to the forefront of the discussion, by some detailed and extensive research by Zodiac enthusiast Kevin Robert Brooks, who can claim to have felt the breath of a killer more than most.

But can Kevin Robert Brooks convince us that Donald Lee Bujok is the killer. Well that is for you to decide.
As an introduction to this suspect, one must first acquaint themselves with the forerunner to this story, 'Donald Lee Bujok-Zodiac Suspect', which details the thought processes the killer used in the design of the Halloween card.
Bearing in mind the killer is approaching his writings from a rationale different from the norm, the key to cracking his codes, may lie in unconventional thinking, held naturally by very few individuals. 
Kevin Robert Brooks also dissects the Exorcist letter and subsequent S.L.A letter, which he believes are inextricably linked by the word "kill".
It is a widely held belief that the footnote of the Exorcist letter stating  "Me-37 SFPD-0", is a reference to his murder count so far. If we believe that his 'tally' was progressive, who and where are all his victims, and why the three year period of inactivity in correspondence. If the killer was incarcerated during this period, then murder on this magnitude is frankly implausible, if we are to believe the Exorcist letter as genuine Zodiac material.
​However, there is an alternative, in that the killer is revealing his age of 37 years, this time attributing it to Me, and not the Zodiac symbol as in previous writings. 

other schoolchildren, and ultimately becoming socially detached. 
Determined to lay claim to some meaning in life, Donald Lee Bujok joined the army, where in 1954 he was stationed at Fort Ord on Monterey Bay. This posting, according to Kevin Robert Brooks, effectively became pivotal in his later correspondence, manifesting itself  in the construction of The Halloween card and envelope, detailed by Kevin Robert Brooks in a Youtube video and previous article on this site.
But another tantalizing clue lay in something Donald Lee Bujok could have retained from his brief spell at Fort Ord, before his medical discharge - this being the writing paper used at the military base.
This may possibly be the same paper used to author the Zodiac letter, sent to the San Francisco Chronicle on July 31st 1969, described on page 446 of Robert Graysmith's 'Zodiac Unmasked'. That being, it was so thin, that the overleaf became visible, measuring exactly 7 and 1/8 inches by 10 and 1/2 inches, identical to the Fort Ord stationary Donald Lee Bujok would have had access to. But after his early contact to the newspapers, wisely switched materials, in order to protect his identity.
Kevin Robert Brooks, crafted by careful research, is steadfast in his belief that his suspect is the Bay Area murderer, and is now more confident than ever, that the breath of his killer, is the one that condensed in the chill of the Lake Herman Road air on December 20th 1968.