On October 22nd 1969, the San Francisco Examiner newspaper published an article by Will Stevens, which laid down a challenge from Professor D.C.B. Marsh of the American Cryptogram Association (ACA) to the Zodiac Killer, attempting to coax him into revealing his name. The newspaper stated "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 Allan Poe, that any cipher created by man can be solved by man. Zodiac has not told the truth in his cipher messages to the Examiner, the Chronicle and the Vallejo Times-Herald. Zodiac has not done this, because to tell the complete truth in relation to his name -in cipher code - would lead to his capture. I invite Zodiac to send The American Cryptogram Association a cipher code - however complicated - which will truly and honestly include his name".

It has been proposed that Dr. Marsh was invoking the name of Edgar Allan Poe to guide the Zodiac Killer down the path of creating a code featured in one of Poe's essays or journals. Just over two weeks later, on November 8th 1969, the Zodiac Killer mailed the recently solved 340 cipher. The scytale method of decryption, that can be used to reveal the message in Zodiac's 340 cipher, was featured in the opening section of Edgar Allan Poe's essay  A Few Words on Secret Writing. The final section of the revealed message in the 340 cipher almost mirrored one of Poe's poems, The final line of the 340 cipher was probably intended to read: "I AM NOT AFRAID BECAUSE I KNOW THAT MY NEW LIFE IS DEATH. LIFE WILL BE AN EASY ONE IN PARADICE". "To One in Paradise" was written by Edgar Allan Poe. This poem was first published as part of the short story titled "The Visionary" (later retitled as "The Assignation"). The poem was also published under the names "To lanthe in Heaven" and "To One Beloved". The title "To One in Paradise" was used in the February 25, 1843 Saturday Musuem. This poem was written after the death of Poe's wife. He writes that she was his life and he lived for her and now he looks forward to the future where they will be together again in death.​ In the Zodiac Killer's 408 cipher, part of the message read: "the best part of it is that when I die I will be reborn in paradise and all the I have killed will become my slaves". The question has always been - what was the inspiration for some of the language he adopted? 

On of the overarching themes in the Zodiac correspondence was his plagiarized acts from The Mikado, 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. The Mikado is the most internationally successful Savoy opera and has been especially popular with amateur and school productions. The work has been translated into numerous languages and is one of the most frequently played musical theatre pieces in history. Setting the opera in Japan, an exotic locale far away from Britain, allowed Gilbert to satirise British politics and institutions more freely by disguising them as Japanese.

​The Zodiac would feature three acts from The Mikado in his July 26th 1970 and January 29th 1974 letters - leading many to believe the Zodiac Killer had an avid interest in the theatre, or quite possibly worked there. His Japanese style characters at the foot of the 1974 Exorcist letter could suggest an affinity to Japanese history or culture. 

Taken from Palladiummag.com: "The world of medieval Japan was one of division. The Emperor was, in practice, a distant memory; the shoguns had lost all control over their vassals. Even shrines and temples, once united in strengthening the state through prayer and ritual, now competed for believers and alms. Japan was divided against itself and circumstances forced its inhabitants to form new bonds to survive. Among the new alliances which this age produced were the Ikkō-ikki, a network of autonomous religious collectives that led major uprisings and controlled significant parts of Japanese society for nearly a century. Their final defeat at the hands of Japan’s warrior class set the stage both for a centralized Japanese state and the social hierarchy behind it. Nobunaga, head of the powerful Oda clan, conquered the capital city of Kyoto in 1568. In the years that followed, he made clear his intention to destroy the Honganji sect. The Patriarch Kennyo took him at his word and summoned all Ikkō-ikki from across the country to defend the faith with their lives. Despite graver circumstances than those faced by his predecessor Shonyo, Kennyo did not go as far as implying that those who fought for the Amida Buddha would be guaranteed rebirth in the Pure Land. Nevertheless, he threatened expulsion from the sect for those who failed to respond to the call and he did not crack down on those who raised the Ikkō-ikki’s now-famous banner of war: “Advance and be reborn in Paradise, retreat and fall immediately into Hell.”

​Bearing in mind the numerous plagiaristic references to The Mikado in his letters, along with the plausible connection between the afterlife poem To One in Paradise from Edgar Allan Poe and the wording chosen in the 340 cipher, was the Zodiac Killer influenced by the Japanese Ikkō-ikki’s banner of war “Advance and be reborn in Paradise" and an affinity for the country's culture and belief system, that ultimately manifested in part of his 408 cipher? Not so much a paradise lost, but a paradise found.​

Some people have considered that the Zodiac Killer may have worked at the San Francisco Chronicle newspaper offices, with inside information pertaining to the investigation days or weeks before its release to the general public. The Zodiac Killer could have (and probably did) mail in excess of twenty communications before October 27th 1970, but not one single communication expressed the Zodiac pseudonym in the form of the letter "Z". This would change on October 27th 1970, when for the first time the Zodiac Killer used the letter "Z" within his Halloween card mailed to Paul Avery. This departure from the norm came just fifteen days before a San Francisco Chronicle article published by Paul Avery on November 12th 1970, which wrote that "the printing on the 'Bates Had to Die' envelopes seemed to match exactly the desk top poem writing. And perhaps the most meaningful discovery was that two of the three notes had been signed with a "Z".

​The Halloween card was mailed by the Zodiac Killer on October 27th 1970, it was addressed to Paul Avery, it referenced Halloween and it contained the letter "Z". Fifteen days later, Paul Avery is reporting on Cheri Jo Bates being found murdered on Halloween morning, with the Bates' letters signed with a letter "Z". Paul Avery's article was likely triggered by somebody (Phil Sins) noticing similarities between the Halloween card and the murder of Cheri Jo Bates, but what were the chances of somebody recognizing something in the Halloween card in respect to the murder of Cheri Jo Bates, pursuing this angle, and subsequently finding a "Z" like signature that mirrored the Halloween card? (used for the first time by Zodiac). What are the chances of Zodiac marrying Halloween and the pseudonym "Z" together, which mirrored the discovery of a murder victim on Halloween morning, which later had accompanying letters signed with a "Z" style signature? The Halloween card coming just three months after the Zodiac Killer mirrored the Cheri Jo Bates Confession letter of "She squirmed and shook as I choaked her, and her lips twiched. She let out a scream once": when he wrote in the Little List letter on July 26th 1970 "Some I shall tie over ant hills and watch them scream + twich and sqwirm".

In a time span of just three months, the Zodiac Killer had combined scream, twich, squirm, Halloween and a "Z" signature, possibly merging crucial details from the Confession and Bates letters together. Four of these details were already available in the January 1969 edition of the Inside Detective magazine, but the "Z" signature was not. If the signature on two of the Bates' letters was really meant to be the letter "Z", then the fact that the Zodiac Killer broke with tradition and used the pseudonym "Z" within a Halloween card for the first time, could be argued as carrying some significance. 

An amalgamation of articles: 
LATEST UPDATE, INCLUDING POLICE REPORTS & PHOTOGRAPHS

Sergeant John Lynch of the Vallejo Police Department received a typewritten card from a "concerned citizen" on August 10th 1969 stating "Dear Sergeant Lynch. I hope the enclosed "key" will prove to be beneficial to you in connection with the cipher letter writer. Working puzzles criptograms and word puzzles is one of my pleasures. Please forgive the absence of my signature or name as I do not wish to have my name in the papers and it could be mentiond by a slip of the tongue. With best wishes. concerned citizen". It also contained a working key to the 408 cipher, which was mailed by the Zodiac Killer in his three "code letters" to the Vallejo Times-Herald, San Francisco Chronicle and San Francisco Examiner on July 31st 1969. On October 7th 1969, another concerned citizen, this time describing himself as a "good citizen", mailed another cryptic message to Sergeant John Lynch, stating "On occasion, while thinking of the code letters, the pencil wrote:Go to 56 Beach Street. I get the name Jerry, perhaps he knows people or his name is XXXXXXX". The author by mentioning "code letters" is clearly referring to the trinity of communications mailed on July 31st 1969, to which the August 10th 1969 communication provided a key. Despite both the "concerned citizen" and "good citizen" communications being extremely brief in nature, both utilized the word "name" twice. The author of these two communications can be argued to be the Zodiac Killer, who also mailed the April 20th 1970 letter, teasing us with "my name is". Crucially, the "concerned citizen" card and code key had not been released into the public domain by the arrival of the "good citizen" letter.  

Recently I have been examining the murder of Robert Michael Salem, who was found stabbed in his 745 Stevenson Street, San Francisco apartment on April 19th 1970. The April 20th 1970 Zodiac Killer letter was received at the San Francisco Chronicle the same day the Robert Salem murder was reported in their newspaper. The letter read "This is the Zodiac speaking. By the way have you cracked the last cipher I sent you? My name is", belatedly followed by "I hope you have fun trying to fiygure out who I killed". The Zodiac Killer chose three Christian symbols in his enclosed 13 character code, that mirrored the Christian symbolism written in blood on the apartment wall of Robert Salem. Above the Japanese tatami mat where Robert Salem's body lay, was the drawing of an Egyptian ankh or "crucified man", along with the wording "Satan Saves" and "Zodiac". The murder of Robert Salem and the April 20th 1970 letter so reeked of Christian symbolism, that it was hard to ignore that the two weren't connected, and led me to believe that the wording "Satan Saves" had some biblical meaning with respect to Robert Salem and his homosexual lifestyle. Whether the drawing of the Egyptian ankh or "crucified man" on the wall of Robert Salem were interchangeable in the mind of the killer is unknown, but the San Francisco Chronicle on April 20th 1970 made no mention of the Egyptian ankh - making the appearance of the Christian anchor in Zodiac's 13-Symbol cipher intriguing. Anchor and ankh have the same phonetic root - and when the Zodiac Killer's crude anchor in the code is superimposed over the ankh drawing on Robert Salem's wall - a full and complete Christian anchor is revealed.   .

The ankh (key of life) was commonly held in the hands of ancient Egyptian deities, or being given by them to the pharaoh, to represent their power to sustain life and to revive human souls in the afterlife. The ankh was one of the most common decorative motifs in ancient Egypt and was also used decoratively by neighbouring cultures. Coptic Christians adapted it into the crux ansata, a shape with a circular rather than oval loop (as seen in the image above), and used it as a variant of the Christian cross. The message of "Satan Saves" rather than "Jesus Saves", along with a crucifix style cross, gives the strong impression of a murder with religious connotations, bearing in mind the anti-gay and intolerant Christian attitudes that permeated society in 1970 (and to a lesser extent today). Robert Salem was a gay man, who may have unfortunately attracted somebody with the belief he was a sinner or non-believer - and hence the sarcastic message of "Satan Saves" and the "key of life" being drawn on his stomach. Clearly, the person who drew the symbol and writing, was portraying a message to the viewer (whether a belief sincerely held or not).

The most unusual and notable features inflicted to the body of Robert Salem, were the crucifix style design "drawn" on his stomach and the removal of his left ear. Both of these featured heavily in the crucifixion of Jesus. Simon Peter, a disciple of Jesus, attempted to "save" and protect Jesus from arrest by severing the ear of Malchus, who was a servant of the Jewish High Priest Caiaphas. According to the gospels, Calaphas organized a plot to kill Jesus. The arrest of Jesus was a pivotal event in Christianity recorded in the canonical gospels. It occurred shortly after the Last Supper (during which Jesus gave his final sermon), and immediately after the kiss of Judas, which is traditionally said to have been an act of betrayal since Judas made a deal with the chief priests to arrest Jesus. This event ultimately led, in the Gospel accounts, to the crucifixion of Jesus. Although the right ear of Malchus was severed, as opposed to the left ear of Robert Salem, this was the most viable connection I could find that links the two unusual features discovered by investigators on the body of Robert Salem.​

The immediate murder with a Zodiac connection after the "latent homosexual" suggestion was floated in the San Francisco Chronicle, where the Bay Area murderer's pseudonym was found at the crime scene, was the murder of gay man, Robert Salem on April 15th 1970 in San Francisco. The Zodiac Killer's 13-Symbol cipher is arguably contemporary in nature, with his April 20th 1970 letter being mailed the same day this murder was published in the newspapers. Homosexuality and acceptance has been a continuing struggle for gay activists to this day, but the 1960s and 1970s were arguably more difficult times, with newspaper coverage on this topic less than acceptable. Many religious people were unwilling to accept individual rights, claiming that homosexuality was the mark of the beast, and was an abomination in the eyes of God. The writing in blood on Robert Salem's apartment wall stating "Satan Saves" must have had some meaning to the killer - so was it in any way connected to the sexual preferences of Robert Salem? I couldn't help thinking that the "Satan Saves" element written in blood on the apartment wall had a more important role to play, not only in the fact Robert Salem was homosexual, but in the damage inflicted to his body and the removal of his left ear. So I looked for a bible verse that may have been known to the killer. 

​I also had to be mindful that the bible verse was relevant to perceived "sins of the flesh". In other words, the murderer of Robert Salem had an issue with homosexuality, believing it to be satanic, and wanted to deliver him unto Satan to be saved (see image above). Hence the wording "Satan Saves". 1 Corinthians 5:5 featured Paul, who had commanded the Christians in Corinth to remove from among them a man who was sleeping with his father's wife, a form of sexual immorality that even their own pagan culture condemned. The killer of Robert Salem may have considered his lifestyle the devil's work and a form of sexual immorality, that resulted in "destruction of the flesh" as witnessed by investigators at the crime scene. I also took the "Satan" element from the apartment wall and combined it with the "destruction of the flesh", to create a relevant solution to the 13-Symbol cipher of "Skin A Satanist". Not only did the Zodiac Killer encipher the word "skin" twice in the 148 character cipher in 1971, but it was relevant to the Robert Salem crime scene in April 1970.

Robert Michael Salem was found murdered in his 745 Stevenson Street San Francisco apartment on April 19th 1970, accompanied by the drawing of a religious crux ansata (crucified man) and the words "Satan Saves" scrawled in blood on the wall. This somewhat mirrored the religious characters in the 13 character code mailed by the Zodiac Killer the following day (April 20th 1970), when he posed the question "I hope you have fun trying to fiygure out who I killed". Investigators found no forced entry at Robert Salem's apartment, and little appeared to have been taken from the property, other than possibly some money from an open wallet on a shelf. The crime scene appeared to scream of far more than a simple robbery. This opens up the possibility that Robert Salem was murdered by somebody known to him, or somebody that befriended him with common interests. Robert Salem was a lamp designer, whose products had been exhibited in Japan, England and Russia. His apartment certainly showed an Oriental influence, with a Japanese hurricane lamp hanging from the ceiling, tree trunks prominent in the apartment in the style of Japanese tea houses, and he was discovered murdered wearing Oriental lounging clothes on top of a Japanese tatami mat.

Three months after this crime, the Zodiac Killer mailed the Little List letter on July 26th 1970, paraphrasing two acts from The Mikado, a Gilbert & Sullivan comic opera set in Japan. The first act he paraphrased was entitled A More Humane Mikado, followed by As Some Day It May Happen, in which victims or society offenders must be found, and who would never be missed. His introduction in the communication detailed how he would torture his victims in paradise, stating in one part: "Others I shall skin them alive + let them run around screaming". In the middle of 1971, the Zodiac Killer would again mention the skinning of victims, when he encrypted the following in his 148 character cipher: "If this is not on the front page in a week I will skin 3 little kids and make a suit from the skin", and wrote in accompaniment to the cipher "Next time I will send a patch of human skin". This is why I found the phrase "Skin A Satanist" very interesting, when from a cryptology standpoint, it satisfied the 13 character code on April 20th 1970, arriving the same day the Robert Salem story broke in the San Francisco Chronicle detailing the "Satan Saves" on the apartment wall. Robert Salem was effectively skinned, when his left ear was severed and taken from the crime scene. On January 29th 1974, the Zodiac Killer would again recite a section from The Mikado, using a verse from Tit-Willow. Not only did he paraphrase the Japanese based opera, but he added some Oriental characters at the foot of the letter. One line in this act reminded me of the introduction in the April 20th 1970 (My Name Is letter). It read "Now I feel just as sure as I'm sure that my name Isn't Willow, titwillow, titwillow", 

Robert Salem was a flamboyant character with an interest in the arts, having been the lighting designer for the historic Haslett Warehouse at 680 Beach Street, San Francisco in 1969. Other than the mention of Washington and Maple streets on October 13th 1969, the only other street the Zodiac Killer ever imentioned in his communications (if authentic} was when he mailed a letter to Sergeant John Lynch on October 7th 1969, when he wrote ''Go to 56 Beach Street. I get the name Jerry, perhaps he knows people or his name is XXXXXXX''. So, was the Zodiac Killer in the apartment of Robert Salem in April 1970?​​​

​​Cragle, an excellent Zodiac researcher who contributes to both forums, sent Michael Morford some invaluable information that he knew I would like (and Mike subsequently added some extra findings). It was fantastic news. A letter was possibly mailed by the Zodiac Killer on October 7th 1969, containing the wording ''Go to 56 Beach Street. I get the name Jerry, perhaps he knows people or his name is XXXXXXX'' (and mentioned code letters). This letter can now be inextricably linked to the Concerned Citizen card postmarked August 10th 1969, which gave us a key to the 408 cipher, mailed by the Zodiac Killer within three "code letters" on July 31st 1969. The 56 Beach Street address never existed in 1969, only on street planning maps. Cragle found a Carl John Welz (married to Jerry Hatcher) who were working at 680 Beach Street, San Francisco and living at 2529 Union Street, San Francisco in 1969, He had a Batchelor and Master of Arts, taught in many public and  private schools and was well known in Christian science circles, with a mentioned periodical from him in 1967 (see below).

If this was the "Jerry" a possible Zodiac Killer was referring to, then this is an enormous find, Carl John Welz (and wife) would most likely have been working at 680 Beach Street at the same time as Robert Michael Salem, who was murdered by somebody claiming to be the Zodiac Killer on April 15th 1970. Throughout 1969, Robert Salem worked as the lighting designer for the historic Haslett Warehouse at 680 Beach Street. Carl John Welz wrote an anti gay article entitled Homosexuality Can Be Healed, so the fact that murdered Robert Salem was a homosexual, with the wording "Satan Saves" and a "crucified man" drawn in blood on his apartment wall, with the pseudonym Zodiac present also, makes this is a significant find. We can now connect the August 10th and October 7th 1969 communications, link the name "Jerry" to the Haslett Warehouse at 680 Beach Street, and to murder victim Robert Salem, who also worked there - and finally - combine the religious overtones from the above article to the apartment wall, and to the Zodiac Killer's 13-Symbol cipher.. 

Robert Michael Salem was found murdered in his 745 Stevenson Street San Francisco apartment on April 19th 1970, accompanied by the drawing of a religious crux ansata (crucified man) and the words "Satan Saves" scrawled in blood on the wall. This mirrored the religious characters in the 13 character code mailed by the Zodiac Killer the following day (April 20th 1970), when he posed the question "I hope you have fun trying to fiygure out who I killed". Investigators found no forced entry at Robert Salem's apartment, and little appeared to have been taken from the property, other than possibly some money from an open wallet on a shelf. The crime scene appeared to scream of far more than a simple robbery. This opens up the possibility that Robert Salem was murdered by somebody known to him, or somebody that befriended him with common interests. Robert Salem was a lamp designer, whose products had been exhibited in Japan, England and Russia. His apartment certainly showed an Oriental influence, with a Japanese hurricane lamp hanging from the ceiling, tree trunks prominent in the apartment in the style of Japanese tea houses, and he was discovered murdered wearing Oriental lounging clothes on top of a Japanese tatami mat.

Three months after this crime, the Zodiac Killer mailed the Little List letter on July 26th 1970, paraphrasing two acts from The Mikado, a Gilbert & Sullivan comic opera set in Japan. The first act he paraphrased was entitled A More Humane Mikado, followed by As Some Day It May Happen, in which victims or society offenders must be found, and who would never be missed. His introduction in the communication detailed how he would torture his victims in paradise, stating in one part: "Others I shall skin them alive + let them run around screaming". In the middle of 1971, the Zodiac Killer would again mention the skinning of victims, when he encrypted the following in his 148 character cipher: "If this is not on the front page in a week I will skin 3 little kids and make a suit from the skin", and wrote in accompaniment to the cipher "Next time I will send a patch of human skin". This is why I found the phrase "Skin A Satanist" very interesting, when from a cryptology standpoint, it satisfied the 13 character code on April 20th 1970, arriving the same day the Robert Salem story broke in the San Francisco Chronicle detailing the "Satan Saves" on the apartment wall. Robert Salem was effectively skinned, when his left ear was severed and taken from the crime scene. On January 29th 1974, the Zodiac Killer would again recite a section from The Mikado, using a verse from Tit-Willow. Not only did he paraphrase the Japanese based opera, but he added some Oriental characters at the foot of the letter. One line in this act reminded me of the introduction in the April 20th 1970 (My Name Is letter). It read "Now I feel just as sure as I'm sure that my name Isn't Willow, titwillow, titwillow", 

Robert Salem was a flamboyant character with an interest in the arts, having been the lighting designer for the historic Haslett Warehouse at 680 Beach Street, San Francisco in 1969. Other than the mention of Washington and Maple streets on October 13th 1969, the only other street the Zodiac Killer ever imentioned in his communications (if authentic} was when he mailed a letter to Sergeant John Lynch on October 7th 1969, when he wrote ''Go to 56 Beach Street. I get the name Jerry, perhaps he knows people or his name is XXXXXXX''. So, was the Zodiac Killer in the apartment of Robert Salem in April 1970?

LATEST UPDATE, INCLUDING POLICE REPORTS & PHOTOGRAPHS

ASSOCIATED ARTICLES:
ANCHORS AWEIGH
ROBERT SALEM-A ZODIAC MURDER?
A CONTEMPORARY CODE ON APRIL 20TH 1970
THE ZODIAC KILLER-DRIVEN BY DEVIANCY     
A SATANIC MESSAGE IN CODE? 
THE "SKIN MARKINGS" ON ROBERT SALEM 
​DELIVER UNTO SATAN

On April 20th 1970, the Zodiac Killer referenced the Park Police Station bombing in San Francisco and the resulting death of Brian McDonnell on February 16th 1970. Eight days later, he mailed the Dragon card to the San Francisco Chronicle asking them to publish the workings of his bus bomb with all the details, with failure to do so resulting in him having his blast. The Zodiac Killer informed the San Francisco Chronicle that he would like to see some nice Zodiac buttons around town. On June 26th 1970, the Zodiac Killer had become upset because the people of San Francisco had not complied with his wishes to wear some nice Zodiac buttons, but had to delay his bombing of a school bus until the Fall, as school was out for the summer. However, he supplied us with a map of San Francisco & Vicinity, stating  "the map coupled with the code will tell you where the bomb is set". So, it's a real head-scratcher where the bomb was to be set? Was it San Francisco by any chance? Or was Fayçal Ziraoui correct when he identified a school in South Lake Tahoe, that wasn't even present on the Phillips 66 Map that Zodiac provided? Many have asked whether it is possible to find the location of the bomb without the extra clues he provided in the Little List letter on July 26th 1970 of "PS. The Mt. Diablo Code concerns Radians & # inches along the radians". Clearly the Zodiac Killer thought it was, when he mailed the map and code on June 26th 1970.

From the above sarcasm, it is reasonable to conclude that the target was a school bus in San Francisco. So how do we find that location? The crosshairs he placed on the map where "0 was to be set to Mag.N", along with the clock face numerals, are a good indication that we must travel around the circumference of Mount Diablo and measure a certain distance from it. However, we can't use individual degrees as a measurement tool, because any number of degrees can fall over the land mass of San Francisco from north to south (and there isn't enough information on the map to conclude which number of degrees is correct). Therefore, we have to find an angular measurement where only one answer exists. If somebody had looked up radians in 1970, they would have concluded that only the whole measurement of 4 radians and magnetic north can fall inside the land mass of San Francisco between its northernmost and southernmost tips. No other radian value can fall within San Francisco. This would have to be the starting point. 

The map scale was in inches and miles, however, the answer could not be in miles because any number of miles can fall inside the land mass of San Francisco between its easternmost and westernmost tips. But using the map scale of 6.4 miles to the inch, only the whole measurment of 5 inches can possibly fall inside the land mass of San Francisco. Had somebody concluded the measurements in radians and inches immediately after receiving the Phillips 66 Map in 1970 using the scant information provided by the Zodiac Killer, then one month later when the Little List letter arrived stating "PS. The Mt. Diablo Code concerns Radians & # inches along the radians", they would likely have been taken seriously. The lack of information on the map meant that we had to be looking for measurements where only one answer was possible for the angle and distance. That answer was whole numbers of radians and inches over San Francisco. Since the code concerned radians and inches, it could be concluded that placing "four radians and five inches" in the code was the obvious choice, before finding the meaning behind the remaining eight characters that painted the full picture. The location the Zodiac Killer selected to claim his bomb placement was a function of roadside, school bus and San Francisco Police Department - so was very unlikely to satisfy such an exact measurement. 

This is the image supplied to us by the Zodiac Killer on the Phillips 66 Mount Diablo map on June 26th 1970. By placing the numbers 0, 3, 6 and 9 around the crosshairs, akin to a clock face, and instructing us that 0 is to be set to Mag. N, the Zodiac Killer is telling us that we have to travel a certain amount of degrees around the clock face from point zero (set to magnetic north, which was 17 degrees in 1970).

The Zodiac Killer realized that the information he provided in the Button letter was insufficient to discover where he was planning to set the bomb. He also realized it was insufficient to solve the 32-Symbol cipher. That is why he placed two crosshairs in his next communication on July 26th 1970. One of the crosshairs contained the radians value, while the other crosshairs contained the inches value. Zodiac wrote:

"P.S. The Mt. Diablo code concerns Radians + # inches along the radians".

It was that simple, all we had to do was place the first crosshairs (shown on the right) over a compass rose. The center of the little black circle with SFPD next to it, landed exactly at 246 degrees, which is 4 radians and magnetic north. That is the answer to the radians value. The target was SFPD.

The second crosshairs had the phrase "P.S. The Mt. Diablo code concerns Radians + # inches along the radians" written over it. Why would the Zodiac Killer place an arrow pointing before the inches value, if he didn't intend for us to place a number here? The answer could only ever be 5 inches, because using the Phillips 66 map scale of 6.4 miles to the inch, only 5 inches falls over San Francisco (4 & 6 inches falls into the sea).
​
The target of SFPD was therefore 4 radians and five inches from Mount Diablo. The target (to a 97.5% accuracy) was the Southern Freeway by Ingleside Police Station, explained in greater detail here.

The Zodiac Killer mailed the Little List letter on July 26th 1970 setting out his search for "society offenders", but this lengthy communication was withheld from publication in the newspapers until October 12th 1970. Despite a comprehensive article in the San Francisco Chronicle on September 26th 1970 featuring the disappearance of Donna Lass from Lake Tahoe on September 6th 1970, the Zodiac Killer never raised his victim total of 13 from July 26th 1970 to October 5th 1970, when the 13-Hole postcard arrived. He never previously needed any prompting to falsely inflate his victim total in previous communications, yet a month after the abduction and likely murder of Donna Lass from the Sahara Tahoe Hotel & Casino, the Zodiac Killer kept his victim total static, suggesting at this juncture he was not claiming the young nurse as victim 14. That is, because he never murdered her. Besides, he would later retrospectively claim he had sought her as victim 12 in the March 22nd 1971 Pines card, while she was still present in San Francisco and working at the Letterman General Hospital by the Presidio.

Donna Lass would have been working as a nurse in the Presidio park in the relevant time period for her to be sought as victim 12. Bearing in mind that the Zodiac Killer was last seen entering the Presidio park after the murder of Paul Stine on October 11th 1969, he knew that by retrospectively claiming he had targetted Donna Lass in San Francisco before her eventual disappearance, it would carry more weight to his suggested involvement in her demise through the Pines card.

The punched hole in the top right corner of the Pines card was never a hint towards her burial location, because the Zodiac Killer had no idea where her body was located. The vague and cryptic phrases pasted on the Pines card were just designed to identify the name of Donna. When the "Sierra Club" was aligned over the Sierra Club of Clair Tappaan Lodge, the punched hole landed over the "Donner" of the Donner Memorial State Park. This was shown to be likely true when a similar pasted card, dubbed the Monticello card, arrived at the San Francisco Chronicle on July 13th 1971, again hinting at the identity of a murdered woman, that of Kathy Bilek. This time, the author pasted "Woods", "April" and "near Monticello" as a clue to her name. However, on this occasion, the sender would actually direct us to a burial site.

Buried in the Oak Hill Memorial Park & Cemetery in the Monticello neighborhood of San Jose was the resting place of Kathie Snoozy, claimed as a victim by the Zodiac Killer in the Dripping Pen card on November 8th 1969. She was the namesake of Kathy Bilek, who along with Debra Furlong, were all victims of the real murderer, Karl Francis Werner. The Monticello card followed the exact pattern of the Pines card, in which the Zodiac Killer retrospectively claimed the April 11th 1971 murder of Kathy Bilek in the Villa Montalvo woods of Saratoga, by pasting "shought victim 21" on the card. He never murdered Kathy Bilek and he never murdered Donna Lass. When Karl Francis Werner was credited with two of Zodiac's previously claimed victims, that of Snoozy and Furlong, he doubled down and more, by adding Kathy Bilek retrospectively in a vain attempt to discredit the notion of Werner being responsible for all three. This belated tactic was used to claim Donna Lass as a victim also, with the Zodiac Killer selecting a time period between the 10 victims on April 20th 1970 and 12 victims on June 26th 1970, while Donna Lass was still working at the Letterman General Hospital for a large chunk of this time. He knew this would add credence to his claim of involvement in her disappearance and likely murder, particularly when he noticed the proximity of her profession to the Washington and Cherry intersection in Presidio Heights.

In fact, the Halloween card, Pines card and Monticello card may have all been retrospective communications, with the Halloween card incorporating the murders of Kathie Snoozy and Debra Furlong into its design by the addition of two skeletons and the 4-TEEN on the card inner. The Zodiac Killer was only claiming four teenagers as murder victims by October 27th 1970, that of David Faraday, Betty Lou Jensen, Debra Furlong and Kathie Snoozy. We know that the Zodiac Killer wasn't responsible for the three victims eventually attributed to Karl Francis Werner, despite him valiantly trying to retrospectively claim all three on numerous occasions. Therefore, we should place little credence to his suggestion of involvement in the untimely disappearance of Donna Lass through the Pines card, especially when he had every chance to elevate his victim total on October 5th 1970. This should give you pause for thought when the Zodiac Killer retrospectively inferred his involvement in Riverside on March 13th 1971, four and a half years after the fact.

Druzer and I have recently been working on the Mount Diablo map code solution, using the measurements of four radians and five inches supplied by the Little List letter crosshairs. Druzer came up with a solution to the 32-Symbol cipher that satisfied the three repeating ciphertext characters in the code, giving us an estimate of where the Zodiac Killer was threatening to "set his bomb". The target was the Southern Freeway alongside Ingleside Police Station, stated in a previous article as 4.08 radians (4 radians} and 4.84 inches (5 inches) from Mount Diablo, indicating that the Zodiac Killer was rounding off his values and giving us an estimate.

It has been stated on this site and elsewhere, that the 32 character code is unsolvable using conventional cipher techniques without the killer supplying us with a key. There are 29 unique characters within the code, making any solution practically unprovable. The solutions offered by using the 408 and 340 keys have produced less than convincing results, particularly when we consider that this code contains an "anchor" and "omega" symbol, not used in the 408 and 340 ciphers. Attempting to correlate the letters used in the code to written text in both the Button letter (June 26th 1970) and Little List letter (July 26th 1970) also produces negative results. Therefore, it could be argued, that a code containing 29 unique characters must have an alternative meaning, in accompaniment to the code solution of "estimate:four radians and five inches".

The Zodiac Killer gave us an estimate of 4 radians, but the actual figure (shown above) was 4.084 radians. That is, 4.084 multiplied by one radian value (57.3 degrees) to equal 234 degrees. When we add in the magnetic north which Zodiac instructed us to do (17 degrees in 1970), we get 251 degrees and the location of Ingleside Police Station. Could the 32 character code contain the value of 234 degrees, which once set to magnetic north, now identified the exact location of Ingleside Police Station? If we resort to basic numerology where A=1, B=2, C=3 etc, and add up the values of the alphabetical characters in the Zodiac Killer's 32 character code, we arrive at a total of 234 (or 234 degrees). When set to magnetic north, it gives us the value of 251 degrees, which when subtended from the peak of Mount Diablo passes directly over Ingleside Police Station and the Southern Freeway. "The map (set to 17 degrees magnetic north) coupled with the code of 234 will tell you where the bomb is set".

On July 26th 1970, the Zodiac Killer mailed the Little List letter with the important clues to the Mount Diablo mystery, stating "PS. The Mt. Diablo Code concerns Radians & # inches along the radians". The answer would be about radians and inches. With the northern section of the map crosshairs positioned at zero and to be set to magnetic north, the Zodiac Killer gave us the value of 4 radians and magnetic north (246 degrees) by the placement of the bold, black circle within the first crosshairs on the Little List letter.

The target was the San Francisco Police Department at Ingleside (SFPD). The second set of crosshairs on the Little List letter contained the hashtag (number sign) in the phrase above, with an arrow placed underneath, beckoning us to insert a number before inches. Only 4 radians and magnetic north, coupled with 5 inches could ever fall over San Francisco, constrained by its land mass. No other values can meet the requirement of targetting SFPD. To an overall accuracy in excess of 98%, the location of the bomb was to be set on the embankment of the Southern Freeway just 274 feet from Ingleside Police Station. For the full story, read The Answer to the Mount Diablo Code.

My solution to the 32-Symbol code in the above article did not marry up the ciphertext to the plaintext adequately, however, Druzer, an invaluable contributor to both Zodiac Killer forums, supplied a solution that married up the three repeating ciphertext characters with corresponding plaintext characters. His solution took "PS. The Mt. Diablo Code concerns Radians & # inches along the radians". into "four radians and five inches" that satisfied the requirement of the Zodiac Killer's Mount Diablo code. This would ultimately provide us with 24 of the plaintext characters for the solution, leaving us 8 ciphertext characters to decode. Druzer came up with the answer, but how was this achieved?     

The problem that materialized, was where to place "four radians and five inches" within the 32-Symbol array. We needed an entry point. The clue had to exist within the ciphertext characters themselves. Two of the most notable ciphertext characters were the Anchor and Omega symbols (the latter of which had never been used before), so possibly it was this symbol that held the key of where to insert "four radians and five inches".

The Omega symbol can be written two ways (shown on the left), with a quick search on Wikipedia revealing information on the radian per second. The radian per second (symbol: rad⋅s−1 or rad/s) is the SI unit of angular velocity, commonly denoted by the Greek letter ω (omega). The radian per second is also the SI unit of angular frequency. The radian per second is defined as the change in the orientation of an object, in radians, every second. 

Using this as the entry point in our ciphertext characters, the word "radians" was placed at the beginning of the Omega sign in the code, hoping that the 24 plaintext characters of "four radians and five inches" would travel to the end of the code. Inserting "four" before "radians", It fell into the code seamlessly (as shown below).

Now we can add in the three plaintext characters represented by O, C and ∆ to the three repeating ciphertext characters in the first section of the code, like so.

Ingleside Police Station is actually 4.08 radians (4 radians} and 4.84 inches (5 inches) from Mount Diablo, so the Zodiac Killer was rounding off his values and giving us an estimate. As can be seen in the above diagram, the word "estimate" fits perfectly into the first eight characters of the code, giving us the final answer to the 32-Symbol code of "estimate: four radians and five inches". The Zodiac Killer was informing us that the answer to the Mount Diablo code of "four radians and five inches" was just an estimate to the location of the bomb at Ingleside Police Station (SFPD). The Merriam-Webster dictionary defines "estimate" as a rough or approximate calculation, which is exactly what it is.

In respect to the Mount Diablo code, the Zodiac Killer gave us two clues to where his bomb was to be set, in the form of two crosshairs on July 26th 1970. The first crosshairs contained a bold, black circle positioned at 4 radians and magnetic north around its circumference. Next to this circle, the Zodiac Killer placed SFPD=0, indicating the target was a San Francisco Police Department. The second crosshairs were overwritten with the wording "P.S. The Mt. Diablo code concerns Radians + # inches along the radians". The hashtag (recognized as a number sign) was positioned above a pointing arrow, beckoning us to insert a number value before inches. The answer is five inches, because this is the only value that falls over San Francisco from Mount Diablo using the map scale of 6.4 miles to the inch. The bomb was to be set alongside Ingleside Police Station, on an embankment bordering the Southern Freeway. For further explanation in simplified form, please visit here, or for more extensive coverage read the article The Answer to the Mount Diablo Code.

Footnote: Ordinarily radians would be measured counter-clockwise, but the Zodiac Killer gave us crosshairs superimposed over Mount Diablo with an arrow pointer set in the north facing position, "to be set to Mag. N". He allocated it a zero position, with a 3, 6 and 9 in the form of a clock face around its circumference. This was to instruct us to travel clockwise around the circumference of the crosshairs in this instance. Which is why it was no fluke that the bold, black circle fell exactly at 4 radians and magnetic north.

The Blast Estimate of Zodiac (Part Two)

The Zodiac Killer often responded to the newspaper articles written about him, usually in close proximity to their release. The Dripping Pen card had likely been purchased subsequent to the morning of October 25th 1969 in response to the last San Francisco Chronicle article by Paul Avery. If the 340 character cipher had been specifically designed to compliment this card, then it too was crafted subsequent to October 25th 1969. As the title attributed to this communication suggests, this greeting card featured a dripping pen on its front face, accompanied by the wording "Sorry I haven't written, but I just washed my pen". The Avery article read "Zodiac struck last on October 11 when he gunned down cab-driver Paul Stine on Washington Street in Presidio Heights. He revealed himself the killer in a letter sent to the Chronicle three days later. Since then he has remained silent".

Bearing in mind the wording "since then he has remained silent", it could be argued that the chosen card of "Sorry I haven't written" was purposefully selected in response to this article - and therefore chosen by the Zodiac Killer after October 25th 1969. The paragraph in the newspaper article also referred to Washington Street, thereby completing the phrase on the card "but I just washed my pen". The last observation is probably a little far-fetched, and heavily reliant on the Zodiac Killer being able to find a greeting card apologizing for being silent, as well as containing a word related to Washington Street. Extremely unlikely, but not impossible.

Then, the day before the November 9th 1969 'Bus Bomb' letter, came the newspaper article detailing the attempted murder of Richmond school teacher, Daniel Williams. Somebody claiming to be the Zodiac Killer made sadistic phone calls spanning October 23rd 1969 and November 2nd 1969, and culminating in a soft drink in his refrigerator being laced with arsenic. This failed murder plot may have inspired the Zodiac Killer (if the poisoner) to insinuate his continued pursuit of Daniel Williams, by stating "I though you would nead a good laugh before you hear the bad news" and "up to the end of Oct I have killed 7 people". On November 12th 1969, the San Francisco Chronicle released information on the Dripping Pen card and Bus Bomb letter under the banner of I've Killed Seven, The Zodiac Claims.

This newspaper article featured the observations of an individual with respect to the X's on the Bus Bomb crosshairs (see right). This observation was suggested in the article The Promise of Murder on Line 5.

I believe the person who initially made this suggestion was almost certainly correct. However, when I floated this idea on November 23rd 2020, I was fully aware of the Mount Diablo map and crosshairs accompanying the Button letter, which was mailed to the San Francisco Chronicle on June 26th 1970. I positioned the Bus Bomb crosshairs over Mount Diablo and rotated them slightly clockwise, so that a line drawn from the peak of Mount Diablo through four of the five X's passed directly over Lake Berryessa, Vallejo (where two attacks occurred), San Francisco and San Jose.

When we consider that this person made the observation on November 12th 1969, seven-and-a-half months before the Mount Diablo map was mailed by the Zodiac Killer (on June 26th 1970), the interpretation by this individual is extremely intriguing.  

The five cross marks cannot directly pinpoint the five claimed attacks in Benicia, Vallejo, Lake Berryessa, Presidio Heights and San Jose by superimposing them over a map. If you arrange any two X's over Lake Herman Road and Blue Rock Springs, the other three X's will never fall over Lake Berryessa, Presidio Heights and San Jose. The only way it is possible, is by placing the crosshairs over Mount Diablo (rotated clockwise} and drawing lines through the X's on the circumference. But this still leaves the 9 o' clock line unaccounted for. This is where Daniel Williams, the Richmond school teacher comes in. The sadistic phone caller to Daniel Williams may have wanted to target schoolchildren at the Richmond school where he worked (Salesian High School falls over the line drawn through the 9 o' clock position}. This is covered in the article A Killer on Line Five.

The newspaper article stated "Zodiac's letter contained five cross marks which possibly refer to attacks. Comparing these markings against a map, one interpretation that can be drawn is that they pinpoint Lake Berryessa, Vallejo (where two attacks occurred}, San Francisco and San Jose". It was effectively saying that five cross marks could pinpoint four locations (identifying Vallejo as the location where two attacks occurred). Despite classifying Lake Herman Road as Vallejo, the tight grouping of the first two attacks on the map would allow the observer to reach the same conclusion as shown in the above map. After all, this person didn't say "Zodiac's letter contained five cross marks which possibly refer to five attacks".

The Zodiac Killer likely chose Mount Diablo because of its use when surveying land boundaries in Northern California, with the summit used as the "initial point". Was it possible that the person behind the interpretation on November 12th 1969 had correctly identified Mount Diablo as the "initial point" to center the crosshairs over, by using the same reasoning as Zodiac? The Zodiac Killer himself classified Lake Herman Road and Blue Rock Springs under the banner of Vallejo (evident on Bryan Hartnell's car door), so when he provided five cross marks to signify four general locations, he was deliberately leaving the 9 o' clock line as a puzzle to the location of his next attack. He employed exactly the same technique, when substituting the X around the crosshairs with a bold, black circle around the circumference of the crosshairs on July 26th 1970, again designed to pinpoint the location of his next attack. On this occasion, it would be a school bus traveling on the Southern Freeway by Ingleside Police Station, positioned at 4 radians and magnetic north.   

After watching the very educational and insightful presentation of Let's Crack Zodiac (Part Four) by Dave Oranchak for the National Cryptologic Museum, the section about the X's positioned around the Bus Bomb crosshairs sparked a fresh interest. Dave Oranchak is correct when he identifies the difficulty regarding scale when overlaying the crosshairs over a map. The Zodiac Killer overlayed his crosshairs over Mount Diablo as part of the Button letter on June 26th 1970, which he followed up with a further clue in the Little List letter on July 26th 1970. The Zodiac Killer explicitly stated that the crosshairs were to be set to Magnetic North (17 degrees in 1970). Therefore, it wasn't particularly surprising that the center of the black circle around the circumference of the first crosshairs on the Little List letter, fell exactly at 4 radians when set to Magnetic North, ultimately identifying Ingleside Police Station as the focus for the bomb.

Two overlays were used to great effect in the June 26th and July 26th communications. It is with little doubt that the Bus Bomb crosshairs were designed to pinpoint locations as well. However, as Dave Oranchak pointed out, the scaling of such an operation is likely to lead to inaccuracy. Therefore, we have to treat the crosshairs on the Bus Bomb letter as a guide. Only a day earlier, the Zodiac Killer had listed his murder count on the Dripping Pen card, mailed to the San Francisco Chronicle on November 8th 1969. He chronologically listed the murders he was claiming by use of months, writing "Des, July, Aug, Sept, Oct = 7".

We know the Zodiac Killer had murdered five victims at Lake Herman Road, Blue Rock Springs, Lake Berryessa and Presidio Heights, but he added in the murders of Kathy Snoozy and Deborah Furlong in San Jose on August 3rd 1969. To this point, the Zodiac Killer had listed his victims, but always left us dangling with the promise of more murders. Would it be all that unusual if the Zodiac Killer again pinpointed these seven victims the following day by use of X's around the circumference of his crosshairs, just like he pinpointed 4 radians and Magnetic North around the circumference of his crosshairs in the Little List letter on July 26th 1970 - with both crosshairs overlayed over Mount Diablo. But in true Zodiac style, the promise of another location in which he would soon murder. If this were the case, we would expect one X on the circumference of the Bus Bomb crosshairs to be unknown.              

To a reasonable degree of accuracy, line [1] falls over Lake Berryessa and the murder victim Cecelia Shepard. Line [2] passes directly over Lake Herman Road and Blue Rock Springs, accounting for David Faraday, Betty Lou Jensen and Darlene Ferrin. Line [3] passes over Presidio Heights and the murder of Paul Stine. Line [4] passes over San Jose and the murders of Kathy Snoozy & Deborah Furlong. These were the locations of his seven victims which he had claimed just a day earlier. One line remains unknown. This line passes over Walnut Creek (where Elaine Davis was abducted from on December 1st 1969, and eventually murdered), as well as Richmond and San Rafael. Had the Zodiac Killer deliberately created this X on the 9 o'clock position as a teaser to his next destination of murder? Next to the bottom right quadrant of his crosshairs on the Bus Bomb letter, he wrote "Be sure to print the part I marked out on page 3 or I shall do my thing". Considering this section of text was placed next to the crosshairs with the X's, was his "thing" going to occur somewhere in the vicinity of Walnut Creek, Richmond or San Rafael, along the unknown line? As far as we know, no murders can be connected to the Zodiac Killer over the next few months in these locations, making you wonder whether this was just another threat that didn't materialize. Or it was simply just a game he was playing.  

FOLLOW UP ARTICLE: A KILLER ON LINE FIVE  

The first three San Francisco Police officers killed in the line of duty in 1970 were Eric Zelms, murdered when he lost control of his firearm when investigating a pawn shop robbery on January 1st. The second was Brian McDonnell on February 16th 1970, who suffered devastating and sadly fatal injuries seven weeks later, when a bomb packed with fence staples exploded on an outside ledge of Park Police Station in the Upper Haight neighborhood. The third was Richard Radetich on June 19th 1970 at 5:25 am, who was gunned down by three shots from a .38 caliber revolver at point blank range through the driver side window of his vehicle while in the process of serving a parking ticket. He was sat in his police car near 643 Waller Street, San Francisco in the Lower Haight District.

The Zodiac Killer didn't personally name any of them, but referred to them indirectly when he stated "two cops pulled a goof", "I hope you do not think that I was the one who wiped out that blue meannie with a bomb at the cop station" and "I shot a man sitting in a parked car with a .38". Additonally, all three communications carried the message of his bomb-making. 

The April 20th 1970 communication not only threatened that there was "more glory in killing a cop", but provided us with imagery that showed he had already set aside a location for his school bus bomb. The Zodiac Killer had specifically chosen a bus route traveling from north to south with a steep embankment on the right and the sun rising to the east. When deciding where to place his bus bomb, one would think the killer would be drawing from experience with regards to the best location. The diagram of the bus bomb location in the April 20th 1970 letter would eventually be discovered to be the embankment directly opposite Ingleside Police Station and alongside the parking lot of the City College of San Francisco. The addition of two crosshairs on the July 26th 1970 "Little List" letter would expand on the Button letter (a month earlier), and show to a 98% accuracy that the target was the Southern Freeway embankment opposite Ingleside Police Station - which was also a bus route. This would effectively kill two birds with one stone for the Zodiac Killer. Was the Zodiac Killer familiar with the City College of San Francisco, having worked at this location or even studied there?   

The Zodiac Killer certainly wanted to paint a picture he was familiar with law enforcement practices, giving rise to the notion he may have worked at, or attended the City College of San Francisco, where he could possibly have crossed paths with Richard Radetich, who attended a criminology course prior to becoming a police officer with the San Francisco Police Department. Greg Corrales was a legendary San Francisco Police officer who knew Richard Radetich and stated that "Richard, who had recently been assigned to Traffic, regularly stopped at Ingleside Police Station to say hello to his former colleagues. He glowed when he talked about his new baby girl and his wife. He was an outstanding police officer and a devoted family man". It is clear that Richard Radetich took criminology classes at the City College of San Francisco before being assigned to duties at Ingleside Police Station just 850 feet east of the college. Richard Radetich had formerly been a student at Balboa High School, 585 meters to the east of Ingleside Police Station. This aligns Sgt. Richard Radetich at the City College of San Francisco (and likely parking lot) studying criminology, with the bus bomb designated for the eastern edge of the parking lot on an embankment, alongside a bus route traveling north to south (with the sun rising to the east), only 274 feet from Ingleside Police Station (where Radetich had worked) - and subsequently - the Mount Diablo code pinpointing this location. The Mount Diablo code letter would also indirectly reference the murder of Sgt. Richard Radetich on June 19th 1970.

It is highly unlikely that the Zodiac Killer was responsible for the murder of Sgt. Richard Radetich, with the previous observations just a simple case of unfortunate coincidences, but it still leaves pause for thought when you consider the location of the bomb had been earmarked in a letter two months in advance of his murder, on April 20th 1970. A letter that highlighted the bombing of Park Police Station and the murder of Brian McDonnell, with the claim that "It just wouldn't doo to move in on someone else's teritory". So, did the Zodiac Killer move to a territory slightly south of Park Police Station, the clue to which lay in the attached bus bomb diagram?

On October 12th 1970, Paul Avery of the San Francisco Chronicle wrote an article concerning the Zodiac Killer's latest two communications, notably the July 26th 1970 "Mikado" letter and the October 5th 1970 "13 Hole" postcard. The Zodiac Killer may have used much of this newspaper article to choose and fashion the October 27th 1970 Halloween card, including a continuance of The Mikado theme. The Zodiac Killer wasn't averse to plagiarising reading material for his communications, with the Halloween card fashioned not only from the Tim Holt comic book, but possibly crafted using the Paul Avery article as his inspiration.

The October 12th 1970 newspaper article was entitled Gilbert and Sullivan Clue to Zodiac, thereby giving the Bay Area murderer about two weeks to find the appropriate reply in the form of a Halloween card beginning "I feel it in my bones you ache to know my name. And so I'll clue you in". The newspaper article detailed "Sheriff's detective sergeant Kenneth Narlow who had fruitlessly followed up another 900 tips as to Zodiac's identity since Sept 27, 1969". So finding a Halloween card teasing us again with his name and offering to clue us in, appeared like the ideal card in response.

In the first column of the article, Paul Avery wrote "Homicide detectives who've been hunting Zodiac for nearly two years frankly admit he is much an enigma now as he was on Dec. 20, 1968, when he chalked up his first two victims". Those two victims were teenagers David Faraday and Betty Lou Jensen. The Zodiac Killer decided to chalk his victims on the Halloween card in white marker pen above the head of the inner skeleton and beneath its feet, in the form of 4-TEEN and what could be Zodiac Victims Fourteen or Zodiac Fourteen.

The author of the card could have written 14 (similar to the outer skeleton hand) or fourteen, but intentionally separated it to 4-TEEN. David Faraday and Betty Lou Jensen were two of Zodiac's confirmed victims, but he had also claimed Deborah Furlong and Kathy Snoozy by the addition of "Aug" in the Dripping Pen card on November 8th 1969, who were both teenagers. The Zodiac Killer had claimed 4-TEENS as victims, hence why he altered fourteen to 4-TEEN, to incorporate them into his running victim total. The addition of four dots (little marks) around ZVF or ZF possibly created for a similar reason. It can be noted that Paul Avery also referred to David Faraday and Betty Lou Jensen in the article as teenagers, but he hyphenated the word into teen-agers, just like Zodiac did with his running teenager total of 4-TEEN.

The majority of the newspaper article focused on the July 26th 1970 "Mikado" letter and the search for potential Ko-Ko's, The Lord High Executioner featured prominantly in the July 26th 1970 (Little List) letter. The Mikado Act One Part 5a  As some day it may happen was performed by Ko-Ko of the town of Titipu. This led investigators to consider the possibility of a Zodiac Killer who played Ko-Ko in his student days. But where was The Mikado and Ko-Ko in the Halloween card? Perhaps the investigators could have searched the knothole in the tree.

The original card came with one eye peeking from the knothole in the tree, in which the Zodiac Killer circled the words "Peek-a-Boo you are doomed". But notice how "Peek-a-Boo" and "you are doomed" are deliberately separated.

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. However, this wasn't the only version of the opera from that time period, In 1888, Ed J. Smith wrote a stage parody of The Mikado called The Capitalist; or, The City of Fort Worth to encourage capital investment in Fort Worth, Texas. In this version, Peek-A-Boo is listed as one of the three sisters and wards of Kokonut (The Lord High Executionist).

The Mikado original featured Peep-Bo: A ward of Ko-Ko and sister of Yum-Yum and Pitti-Sing. Peep-Bo is the British version of Peek-a-Boo. 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.

Peep-Bo can also be reversed to Bo-Peep, believed to originate from the 16th century practice of concealment, before reappearing to startle or surprise. See here. Little Bo Peep is a popular English nursery rhyme 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), but little evidence that the rhyme existed. 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.

The phrase "to play bo peep" was in use from the 14th century to refer to the punishment of being stood in a pillory. For example, in 1364, an ale-wife, Alice Causton, was convicted of giving short measure, for which crime she had to "play bo pepe thorowe a pillery". Andrew Boorde uses the same phrase in 1542, "And evyll bakers, the which doth nat make good breade of whete, but wyl myngle other corne with whete, or do nat order and seson hit, gyving good wegght, I would they myghte play bo pepe throwe a pyllery". Taken from Wikipedia. The skeleton on the card inner also appeared to be hanging in the form of punishment, as if placed in a pillory. I suppose the "punishment must fit the crime".

Bearing in mind the newspaper article of Paul Avery, was the Halloween card drawing on the search for Ko-Ko's by its design of inserting Peek-a-Boo around the knothole of the trunk, with the eye "hiding behind that tree"? Was the chalked-up victim count of 4-TEEN above the pilloried skeleton denoting the running total of fourteen, including four teen-agers? The newspaper article of Gilbert and Sullivan Clue to Zodiac may have spawned the choice of Halloween card with the introduction of "I feel it in my bones you ache to know my name. And so I'll clue you in". But did it inspire anything else?

The problem with solving the Zodiac Killer's 32 Symbol cipher and Phillips 66 Map code, is a failure to follow the instructions given by the killer in the June 26th 1970 letter and its follow up on July 26th 1970. The Zodiac Killer stated "The map coupled with this code will tell you where the bomb is set.  You have untill next Fall to dig it up". This tells us that the solution to the 32 symbol cipher will not supply us with the exact position of the supposed bomb. Any solution to this 32 character code pinpointing the exact position of the bomb will be incorrect, because this can only be realized by coupling it with the map. Therefore, the position of the bomb to be set, was a combination of both code and map.

In his following letter he stated "P.S. The Mt. Diablo code concerns Radians + # inches along the radians". This tells you that the code is about radians and inches but not necessarily the entire solution. Any solution to the position of the bomb that doesn't use radians and inches (as implicitly stated by the killer) will be wrong. The phrase "P.S. The Mt. Diablo code concerns Radians + # inches along the radians" would supply the inches value, hence the hashtag before inches, along with the arrow beneath, instructing us to insert a value here. This isn't rocket science - the hashtag is widely recognized as a number sign, so by placing this immediately before the word "inches", the Zodiac Killer is telling us to insert a number before inches. The only way to find a bomb in Northern California using his instructions, is to travel a set amount of radians around his crosshairs, and then subtend a set amount of inches from it. In this case, a number of radians around Mount Diablo and a number of inches from it. Placing a hashtag and arrow before the word "inches", is rather a giveaway that a number value should precede it. Even the map code was 6.4 miles to the inch. Any solution that gives us the answer in degrees or miles is wrong, because "The Mt. Diablo code concerns Radians + # inches along the radians". We need to follow his instructions. This is why any theory of crime scene locations being chosen because they are separated by a radian or near radian value, is wrong also. The whole premise of the June 26th 1970 letter was to discover the location of his bomb, not measure angles between crime scenes or any other object we choose to construct or imagine

The Zodiac Killer gave us crosshairs superimposed over Mount Diablo with an arrow pointer set in the north facing position, "to be set to Mag. N". He allocated it a zero position, with a 3, 6 and 9 in the form of a clock face around its circumference. This was to instruct us to travel clockwise around the circumference of the crosshairs, to be set at 17 degrees (which was the magnetic north value in 1970). We had to travel a set amount of radians around his crosshairs over Mount Diablo, in addition to this value of 17 degrees. So, we are looking for a set amount of inches and a set amount of radians. The Zodiac Killer was incapable of keeping secrets and resisting putting pen to paper, so just one month later he gave us the answer, when the July 26th 1970 letter arrived at the San Francisco Chronicle.          

Never done before or since by the Zodiac Killer, he drew a big fat zero around the circumference of his crosshairs with SFPD alongside it. This represented the San Francisco Police Department. This bold, black circle sat at 246.2 degrees, which is 4 radians and magnetic north. This was the radian component of "The Mt. Diablo code concerns Radians + # inches along the radians". The answer was 4 radians. All we had to do now was find the "inches" value.

The Zodiac Killer mailed virtually every correspondence to the San Francisco Chronicle, describing the makeup of his bomb on November 9th 1969. He followed this up with a diagram of a school bus and photoelectric cells on April 20th 1970, referencing the murder of San Francisco police officer Brian McDonnell on February 16th 1970, who suffered devastating and sadly fatal injuries two months earlier, when a bomb packed with fence staples exploded on an outside ledge of Park Police Station in the Upper Haight neighborhood of San Francisco. The Zodiac wrote about the "blast" he was going to have when he mailed the Dragon card on April 28th 1970. All of these communications directed towards the San Francisco Chronicle indicating he was constructing a bomb, with the SFPD attribution totaling zero adorning many. Therefore, it's pretty obvious that placing SFPD around the circumference of his crosshairs, next to a big fat zero and set to a value of 4 radians and magnetic north (4 X 57.3 + 17), indicates that the target for the bomb is San Francisco - or more specifically - the San Francisco Police Department. When the above crosshairs are set over Mount Diablo, we now have to travel 4 radians and magnetic north from the peak of the mountain. Let us now find the inches value to be inserted into "Radians and # inches along the radians".

We actually don't have to look hard to find the answer. The land mass and geography of San Francisco is such, that only 5 inches can fall over it. Using the map scale of 6.4 miles to the inch, anything less than 5 inches, and anything more than 5 inches, doesn't fall inside San Francisco. Therefore, there is only one answer. The same applies to the radians value. Anything more or less than 4 radians and magnetic north (such as 5 radians and magnetic north, or 3 radians and magnetic north), doesn't fall inside the geography of San Francisco. A bomb threat on San Francisco (hence SFPD=0), can only be 4 radians and magnetic north, and 5 inches along that radian value. The choice of words by the Zodiac Killer when he wrote "Radians and # inches along the radians". were chosen carefully. We were instructed to find "radians", and an amount of "inches" along the amount of "radians" we found. Once we found the radians value, we would travel 5 inches along that radian. The answer to the map was the magnetic north value of 17 degrees, to be coupled with four radians and five inches of the code. The two "coupled" together gave us the full answer. Druzer, an avid Zodiac researcher, came up with a solution to the 32 character code which I believe is correct, when he suggested Estimate: four radians and five inches. This solution not only satisfies the 32 characters, but correlates three plaintext letters to the only three repeating ciphertext characters in the code, thereby providing a perfectly valid key. See The Blast Estimate of Zodiac, The Blast Estimate of Zodiac (Part Two). and The Blast Estimate of Zodiac (Part Three).

The map scale is 6.4 miles to the inch. This gives us a distance of 6.4 multiplied by 5 (inches). Therefore, the bomb was to be set at 4 radians and magnetic north, and 32 miles from the peak of Mount Diablo. The only San Francisco Police Department that comes anywhere close is Ingleside Police Station. This San Francisco Police Department sits at 30.96 miles from the peak of Mount Diablo (4.84 inches). It also sits at 251 degrees from the peak of Mount Diablo (4.08 radians).

The Zodiac Killer gave us a rough guide of 4 radians and magnetic north, and 5 inches (hence the word "estimate"). If he had given us the exact measurement, it would have been 4.08 radians and 4.84 inches, He was clearly giving us an approximate measurement. Since Ingleside Police Station was the only San Francisco Police Department anywhere close to these measurements, it's fairly obvious this was his target. The Zodiac Killer's distance in miles was 96.8% accurate. His angular accuracy in degrees was 98.0%. The Zodiac Killer was very unlikely to have selected a specific target that fell on an exact whole number of radians and inches.   

The Zodiac Killer was targeting Ingleside Police Station for his bomb, but clearly he wasn't going to start digging a hole on the lawn of Ingleside Police Station. The Zodiac Killer also threatened to blow up a school bus on April 20th 1970, in which he drew us a diagram with a steep embankment on the right, with the sun rising to the east. This would suggest we should be looking for a bus route traveling from north to south (where the sun rises to the east in the morning), with a steep embankment to the right of the bus, where the Zodiac Killer can lay his photoelectric cells and conceal his bomb. He also has to access that roadway from a position of anonymity, with his vehicle parked at the top of the embankment in relative seclusion. What are the odds of that location being the exact closest portion of road to Ingleside Police Station, meeting all the criteria above. This would satisfy the drawing on the April 20th 1970 letter and the target of SFPD (Ingleside Police Station). The Zodiac Killer could metaphorically kill two birds with one stone.

So let us travel just 274 feet from Ingleside Police Station to the nearest section of road heading north to south.

Again, what are the chances that the area highlighted by the red rectangle would mimic exactly his bomb diagram of a school bus and embankment, as drawn in the April 20th 1970 letter. Not only that, but this would have been a school bus route in 1970. Children from the northern and eastern areas of San Francisco would use the school bus to reach St Thomas More Catholic School at 50 Thomas More Way. There is even a bus route road sign 38 feet from the proposed location of the bomb (whether it existed in 1970 I don't know). So, let us drop down to the exact position of the red rectangle and take a closer look.

All the Zodiac Killer had to do to access the embankment, was to access the parking lot of the City College of San Francisco and drive to its eastern edge - and at night - in relative anonymity to the police station, dig the bomb into the embankment. It is highly unlikely that the Zodiac Killer ever intended to plant a bomb, but this location fits all the criteria of targeting both a San Francisco Police Department and a school bus at the same time. It achieves his objective of targeting school children for maximum terror, and achieves his objective of "rubbing the pigs nozes in their booboos". The location of the bomb not only matches the diagram from April 20th 1970, but satisfies the criteria of the Mount Diablo map and code to an overall accuracy of 97.5%. The 32 character cipher is also answered. The Zodiac Killer likely had no intention of laying this bomb, but it was the threat that mattered most of all. The Zodiac Killer knew that the clues he provided us with on June 26th 1970 were inadequate in cracking the bomb location and code, so he gave us these additional clues in the Little List letter on July 26th 1970, one month later.

# Radian values are normally measured in a counter-clockwise direction, but the positioning of the bold, black circle at 246 degrees (4 radians and magnetic north), along with the north facing arrow pointer, the addition of the clock face set at zero, and the instructions to "set to Mag. N.", appears to indicate the Zodiac Killer measured his radians from the north position clockwise. In effect, he was multiplying the radian value of 57.3 by a factor of 4, set to magnetic north of 17 degrees (246.2).   

It has been stated on this site and elsewhere, that the 32 character code is unsolvable using conventional cipher techniques without the killer supplying us with a key. There are 29 unique characters within the code, making any solution practically unprovable. The solutions offered by using the 408 and 340 keys have produced less than convincing results, particularly when we consider that this code contains an "anchor" and "omega" symbol, not used in the 408 and 340 ciphers. Attempting to correlate the letters used in the code to written text in both the Button letter (June 26th 1970) and Little List letter (July 26th 1970) also produces negative results. Therefore, it could be argued, that a code containing 29 unique characters must have an alternative meaning, in accompaniment to the code solution of "estimate:four radians and five inches". Here is one possibility. 

The Zodiac Killer gave us an estimate of 4 radians, but the exact figure is 4.084 radians. That is, 4.084 multiplied by one radian value (57.3 degrees) to equal 234 degrees. When we add in the magnetic north which Zodiac instructed us to do (17 degrees in 1970), we get 251 degrees and the precise location of the Southern Freeway embankment and Ingleside Police Station. Could the 32 character code contain the value of 234 degrees, which once set to magnetic north, now identified the exact location of Ingleside Police Station? If we resort to basic numerology where A=1, B=2, C=3 etc, and add up the values of the forward facing alphabetical characters in the Zodiac Killer's 32 character code, we arrive at a total of 234 (or 234 degrees). When set to magnetic north, it gives us the value of 251 degrees, which when subtended from the peak of Mount Diablo passes directly over Ingleside Police Station and the Southern Freeway. 

​    "The map (set to 17 degrees magnetic north) coupled with the code of 234 will tell you where the bomb is set".