You can tell if a fingerprint is from a left or right hand by analyzing specific patterns like the whorl axis slant, which shows a statistically significant tendency to slant one way or the other depending on the hand. Other methods involve analyzing multiple parameters within the fingerprint's ridges, such as the slope of the ridges, the positions of the core and deltas, and ridge counting. For loops, the direction of the flow can also be a key indicator: ulnar loops, which flow toward the pinky finger, are more common on the right hand, while radial loops (flowing toward the thumb) are more common on the left. ​

A Zodiac Killer without gloves (and minus effective airplane fingertip guards, or none at all) would inevitably have deposited fingerprints on the outside front right passenger door handle when entering the front of the taxicab. When the Zodiac Killer was seen leaving this door by the Robbins teenagers, they described a suspect who then "exited the cab by the passenger side front door, also wiping with a white rag, possibly a handkerchief. The suspect then walked around the cab to the driver's side and proceeded to wipe the exterior of the left door area". The white rag was most probably the cut section of Paul Stine's shirt. But how does a right-handed killer, who might be expected to use this hand when wiping down the taxicab, manage to leave a left ring fingerprint on the outside front passenger door handle? There are multiple possibilities.

If the Zodiac Killer had used scissors or a knife to cut the shirt of Paul Stine, he would have used his right hand, leaving his left hand free to secure the freed shirt piece. If he had immediately left the taxicab after performing this task, his left hand would have still been in possession of the shirt piece, which he could have then used to quickly wipe the door handle as he exited. Alternatively, he may have put the scissors/knife away while inside the taxicab and subsequently grabbed Paul Stine's wallet and Yellow Cab keys using his right hand, while still clutching the shirt piece with his left. As he departed the front passenger side of the taxicab he may have then pocketed the wallet and keys, obviously keeping the shirt piece in his left hand to wipe down the door handle. This would explain why a right-handed individual attempted to remove fingerprints with his left hand. So how was the bloody left ring fingerprint of Zodiac inadvertently deposited on the door handle?

The above image shows the door handle of a Ford Galaxie 500 taxicab. If the Zodiac Killer was clutching a portion of the shirt piece with his little finger and thumb, and wiping up and down and/or horizontally across the inside of the door handle with the three longest fingers (digits 7, 8 and 9) by positioning his hand at either the top or bottom of the door handle, it is easy to see how the side (or front) of his left index or left ring finger could accidentally make contact with the inner edges of the door handle. That is why it would be important to know the exact location and orientation the bloody left ring fingerprint was positioned on the door handle. 

Elimination prints were taken of responding personnel who attended the Presidio Heights crime scene, as they were of San Francisco Chronicle staff and members of the police department who touched the "Little List" letter mailed on .July 26th 1970. Therefore, the bloody fingerprint found on the taxicab and the latent left ring fingerprint retrieved from the "Little List" letter exhibiting similarities to one another, have a strong possibility of originating from the hand of our killer. Any fingerprints found on the inner pages of the five-page "Little List" letter (protected by the front of page 1 and the rear of page 5), one might expect to be the fingerprints of the author, had the San Francisco Chronicle staff ceased further examination once they read the introduction of "This is the Zodiac speaking". This, of course, assumes that the Zodiac Killer folded pages 1 to 5 in order. There should be very little to no reason why a machine produced writing pad should contain any fingerprints on its inner pages, other than that of the Zodiac Killer. Especially when using five consecutive pages over a constrained time period to author this letter.

It is clear that the similarity between the left ring fingerprint from the "Little List" letter and Presidio Heights crime scene did not extend to any database search results, that included subjects such as Arthur Leigh Allen, who quite frankly should have been removed from the suspect list decades ago. All of the eight latent fingerprints retrieved from the "Little List" letter were compared to "suspects" in the Zodiac case and no match was effected. 

Dion Walker summed everything up nicely, stating "Is it really so much of a stretch - so hard to believe - that it's probable for two latent fingerprints from two different surfaces, that had both been checked against elimination prints - and were almost certainly touched by the exact same man - were similar because they were left by the same man. I think it makes sense looking at the whole picture". If the left ring fingerprint of a "suspect" exhibited similarity to the left ring fingerprint from the "Little List" letter, which itself showed a similarity to the one retrieved from the tacicab of Paul Stine, this would be our starting point. The remaining seven latent fingerprints from the same letter could then be used to compare to other digits from the "suspect", which should reasonably effect an identification (or not) of the man who masqueraded as the elusive Zodiac Killer.
​I would like to again thank Dion and Cragle for tackling this extremely labor intensive subject, and for three of the images used in the above presentation.

SEARCHING FOR THE PRINTS OF ZODIAC 
AN INITIAL CUT TO THE LEFT SIDE [PART ONE]
AN INITIAL CUT TO THE LEFT SIDE [PART TWO]

From July 31st 1969 to March 13th 1971 virtually all Zodiac communications contained the signature of the "crosshairs", placed at the foot of each correspondence only once (with the exception of the 340 cipher). The "Little List" letter, postmarked July 26th 1970 and received by the San Francisco Chronicle the following day, contained two large crosshairs and deviated from his worded letters by having this extra addition. The first crosshairs mailed to The Chronicle carried the victim total of 13 (which would normally finish a communication). If the Zodiac Killer had either sealed this envelope, or already mailed this communication, it's possible he felt the need to write a second letter which began "As some day it may hapen" from Gilbert & Sullivan's "The Mikado", with a second crosshairs signature containing the crucial phrase of "P.S. The Mt. Diablo code concerns Radians + # inches along the radians". In other words, the Zodiac Killer mailed two communications on (or shortly before) July 26th 1970.  

The San Francisco Chronicle on October 12th 1970 clearly stated that two letters were "sent to The Chronicle last July 27". In the San Jose Sunday Mercury newspaper they reported that "This was the new total he claimed in two letters received July 27 by the San Francisco Chronicle and kept secret until now by agreement with police while the letters' contents were analyzed. The longer of the two letters begins: "As some day it may happen that a victim must be found". Bearing in mind that these two letters were kept "secret" by investigators and the San Francisco Chronicle for 2 1/2 months, it probably isn't surprising that the Zodiac Killer chose a greeting card with the opening line "From your secret pal".​

​The San Francisco Chronicle newspaper article on October 12th 1970 was entitled "Gilbert and Sullivan Clue to Zodiac", so again, the greeting card's following line of "I feel it in my bones, You ache to know my name, And so I'll clue you in" was perfectly chosen. It is fairly obvious that the Halloween card was mailed in response to the San Francisco Chronicle newspaper article on October 12th 1970. The Zodiac Killer even mimicked the "chalk-like writing" on the presale card to add "4-TEEN" onto the greeting card inner. The newspaper stated "And he is now claiming he has murdered 13 persons. Homicide detectives who've been hunting Zodiac for nearly two years frankly admit he is as much an enigma now as he was on Dec 20, 1968, when he chalked up his first two victims" (which were David Faraday & Betty Lou Jensen). In this period of nearly two years the Zodiac Killer only ever claimed the lives of 4 teenagers, who were David Faraday, Betty Lou Jensen, Kathie Snoozy and Debra Furlong. Therefore, David Faraday & Betty Lou Jensen were probably included in his "chalked" 4-TEEN victim total. 

​The two large crosshairs may have ended each letter received by the San Francisco Chronicle on July 27th 1970, to begin the outside possibility we have a second envelope either lost or misplaced. However, It must be stressed that it's unlikely two letters were mailed by the Zodiac Killer when we re-evaluate the wording contained within the newspapers, which are in direct conflict with several FBI files that document a "Five page letter and envelope". But if one envelope did get misplaced, this would be the obvious conclusion.      

One of the strangest offerings of the Zodiac Killer was the 32-Symbol cipher on June 26th 1970, but why did he design a cipher with 29 individual ciphertext characters and only three repeating, with practically no chance of a solution? The unusual answer to this question, is that the Zodiac Killer thought in 30 days this cipher had a reasonable chance of being solved, because he designed it in two parts. Knowing that the second part of the puzzle was to arrive on July 26th 1970, he deliberately engineered the first part with no reasonable prospect of a solution, with the answer available in the second instalment. The Zodiac thoroughly expected that once his "Little List" letter arrived at the San Francisco Chronicle on July 26th 1970, the solution to the 32-Symbol cipher would soon be discovered. However, it would take another 50 years to solve, when Andrew Gray (Druzer) forwarded me the solution on December 27th 2020.

​After the remarkable achievements of Dave Oranchak (USA), Sam Blake (Australia) and Jarl Van Eycke (Belgium) in cracking the 340 cipher earlier that month, we now had another massive breakthrough. The Zodiac had created the 32-Symbol cipher with 29 unique characters - because had he not done so - he knew that the extra clues he was going to provide on July 26th 1970 would have made it far too easy. The fact that he gave us such little opportunity to solve the 32-Symbol cipher on June 26th 1970, was effectively the evidence there was going to be further clues forthcoming. He likely knew this from the very start, which explains the difficulty of his original offering. You would only create an unbreakable cipher in June, if you knew the answer was coming down the tracks in July. The solution was so extremely simple, it was overlooked by everybody apart from Andrew Gray, Having previously identified that the only viable solution was a measurement of four radians and five inches to locate the bomb, I failed to understand that these were the measurements to be placed directly into the cipher. Fortunately, Andrew Gray was on hand to fit the final pieces into the jigsaw. The solution can be explained in three easy parts.

[1] The first crosshairs in the "Little List" letter gave us a prominent black circle positioned at four radians and magnetic north around its circumference (246.2 degrees), with the target SFPD (San Francisco Police Department) next to it. We had to travel four radians around the circle, with the zero position (from the map below left) set to magnetic north (17 degrees).
​4 multiplied by 57.3 degrees (radian value) plus 17 = 246.2 degrees.  

​​[2] The second crosshairs (see orange image below) in the "Little List" letter gave us most of the solution to the 32-Symbol cipher, where Zodiac wrote "The Mt. Diablo Code concerns Radians & # inches along the radians". He told us that the code concerned (was about) "Radians & # inches". The Zodiac didn't place a hashtag before the radians value because he had already given us that value in the first crosshairs. It was "four Radians & # inches". All we had to do now was add the inches value to where the Zodiac had placed an arrow pointing to the hashtag. 

​Despite the relatively recent explosion in popularity of the hashtag on social media, the hashtag is often used as a number sign, such as "#1" instead of "number 1", The Zodiac Killer was instructing us to insert the number five before inches. Hence his use of the hashtag. The target of SFPD (San Francisco Police Department) can only be five inches based on the Mount Diablo map scale of 6.4 miles to the inch, because this is the only amount of inches that can possibly land over San Francisco from the peak of Mount Diablo. Equally, four radians is the only amount of radians that can fall over San Francisco from Mount Diablo. We now have the answer of "four Radians and five inches". There was only ever one possible answer.   

[3] The location that Zodiac chose to identify for his buried bomb - the embankment opposite Ingleside Police Station (SFPD) - only fell close to whole radians and inches (it was 4.08 radians and 4.85 inches), so he approximated the measurements and rounded them off to four and five. An approximate calculation is an "estimate", hence the final solution of "estimate: four radians and five inches" (set to magnetic north).   

You will notice that when Zodiac placed "four radians and five inches" from positions 9 to 32 in the cipher, he repeated no ciphertext characters. From positions 1 to 8 he then selected three ciphertext characters to repeat in the word "estimate" to make the cipher solvable. This made the first word in the cipher self-evident, because this was the only word in the 32-Symbol cipher that required extra clues. The only mystery remaining, is why Andrew Gray doesn't get the recognition he fully deserves for cracking this supposedly unsolvable cipher. All the ciphers so far solved in the Zodiac case are easily explained once their mystery is unlocked - and this cipher is no different. It is a simple three step process.  

On June 26th 1970 the Zodiac Killer was telling the truth when he wrote "the map coupled with the code will tell you where the bomb is set". The code of "four radians and five inches", to be coupled with the map crosshairs "to be set to magnetic north", gave us the complete answer of "four radians set to magnetic north and five inches". The use of radians and inches on July 26th 1970 was an admission that the original letter on June 26th 1970 didn't meet the requirements for a solution to be satisfactorily achieved. The answer was ultimately embedded in three crosshairs spanning thirty days (06/26/1970 magnetic north, 07/26/1970 four radians, 07/26/1970 five inches)..

On the morning of October 27th 1970 the San Francisco Chronicle featured an article by Paul Avery entitled "A Jack the Ripper Theory on Slayings", highlighting the recent murder of Jackie Truss (16) on October 24th 1970, whose tortured, slashed and beaten nude body was discovered in the early morning hours on the "tree-lined" Laurel Street (between Jackson & Pacific Streets) in Presidio Heights. She had ligature marks on her wrists, her throat and eyelids had been slit with a knife, she had been partially disemboweled and her killer had tortured her "by fire".

Jackie Truss was the third in a series of similar murders, beginning with Brenda Joyce Vance (23) on August 4th 1970, who had also been tortured, burnt and bludgeoned to death, and found on the sidewalk of Golden Gate Avenue. On August 30th 1970 Janice Smith was discovered in a condemned dwelling on Webster Street, having been tied, slashed with a long-bladed dagger and burnt. In 1973 somebody was eventually charged with the first two murders and was thought to be responsible for the third. The final murder was unlikely to have been committed by the Zodiac Killer, but did he mail the Halloween card to Paul Avery on the afternoon of October 27th 1970 in response to the newspaper article by Paul Avery from that morning, entitled "A Jack the Ripper Theory on Slayings"? After all, the Zodiac Killer wasn't immune to insinuating his involvement in murders he played no part in. He never outright claimed the murders of Donna Lass, Kathie Snoozy and Debra Furlong, but left many cryptic clues throughout his campaign of literary terrorism suggesting he was the responsible.  

The Little List letter on July 26th 1970 (but not released to the public until October 12th 1970 by Paul Avery) told of the Zodiac Killer's desire to "torture all 13 of my slaves that I have waiting for me in Paradice" and that "Others shall have pine splinters driven under their nails + then burned". The Zodiac Killer continued his infatuation with torture, writing that "Others will hang by their thumbs + burn in the sun". The newspaper article below about Jackie Truss, released in the days before the Halloween card, told of a girl "tortured by fire", with a fractured skull and slit eyelids, lying on a "tree-lined" street, that were all key ingredients on the Halloween card, which contained a victim count above the skull, thirteen eyes (with eyelids and eyelashes) and the four methods of death "By Fire, By Gun, By Rope and By Knife". The Halloween card also had red eyes added to the skull on the card outer. A card that was personally addressed to Paul Avery, who had written about the knife slaying of Jackie Truss, whose body was found in Presidio Heights days earlier, who had been tortured "by fire".

Jackie had been living with a man in the Marina District at the time of her death, who police were attempting to trace at the time of this newspaper article. It was suspected that she had been murdered at a residential location and dumped adjacent to 55 Laurel Street near the Presidio Park, evident by the lack of blood at the crime scene, not withstanding the fact that this location was not conducive to such a depraved murder. It was estimated that she had been dead for less than one hour when her body was discovered by two college students on Saturday, October 24th 1970 at 2:45am.   

Thanks to Zodiac researcher Cragle for sending me this information. ​

Many Zodiac researchers have contemplated which production of The Mikado inspired the Zodiac Killer to plagiarize two acts from the Gilbert & Sullivan opera, that included "A More Humane Mikado" and "As Some Day It May Happen" on July 26th 1970. Hopefully the following presentation may help answer that question.

​Although the Zodiac Killer heavily featured The Mikado in the July 26th 1970 letter, it wasn't his first reference to the satirical play, when he wrote about Kathleen Johns two days earlier (on July 24th 1970), stating "This is the Zodiac speaking. I am rather unhappy because you people will not wear some nice (Zodiac symbol inserted) buttons. 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". The Zodiac Killer was effectively pre-empting his "Little List" letter mailed to the San Francisco Chronicle on July 26th 1970. The Bay Area murderer was often a reactive author, commenting on recent newspaper articles he had read, or something he had watched on television.

Throughout California (and other regions of America), the D'Oyly Carte 1939 production of The Mikado was featured on Channel 11 on the late night of Thursday, July 23rd 1970 and the early morning hours of Friday, July 24th 1970. That is the night before and the same day that the Zodiac Killer mailed his brief letter to the Chronicle, claiming the abduction of Kathleen Johns, and informing us that he had begun his "little list". Below are just a few examples from California.   

Curiously, but not by any means compelling, The Mikado (1939) starred Kathleen Naylor (the namesake of Johns), who joined the D'Oyly Carte Opera Company in 1933 and also played key roles in Gilbert & Sullivan's "Princess Ida" and "Iolanthe". But that isn't the interesting part of the story. Widely considered the next confirmed communication of the Zodiac Killer, the Halloween card was mailed on October 27th 1970 with the added wording of "Peek-A-Boo" and "Boo". Bearing in mind that The Mikado was a British production, "Peek-A-Boo" is usually referred to as "Peep-Bo" in the English equivalent. Kathleen Naylor played the character "Peep-Bo" in the 1939 version of The Mikado.   

The Zodiac Killer gave us two working electrical circuits in his November 9th 1969 and April 20th 1970 bomb diagrams, threatening to blow up school buses in California. But how familiar was the Zodiac Killer when it came to circuitry and electronics? Did his profession require a knowledge of electronics, or did he simply copy the bomb-making designs from the publications he read?

​In the last article it was shown how the word "radians" began on the ciphertext symbol of Omega (in the Z32 code), taken from the concept that "The Mt. Diablo Code concerns Radians & # inches along the radians" formed the basis of the Z32 answer. When you consider that the Zodiac Killer placed a bold, black circle in his crosshairs with SFPD alongside (in his Little List letter), positioned at 4 radians and magnetic north, it becomes fairly obvious that the target was San Francisco. Only "four radians and five inches" fell inside San Francisco using the map scale provided.

If the Zodiac Killer was fairly adept in his knowledge of electrical circuits (having used the term radians), he would have known that "Radians and angular velocity are terms that are commonly used in AC theory and AC measurement. Most of the electric energy used commercially is generated as Alternating Current (AC). The main reason Alternating Current is used is that alternating voltage may be easily raised or lowered in value. This is a tremendous advantage in electrical distribution systems, allowing AC power to be generated and distributed at a high voltage and reduced to a more practical voltage at the load". Link to the Electronics Technician Training website. The Zodiac Killer would likely have known that "angular velocity" is represented by the lowercase Omega sign (ω), and that "angular velocity is another term that's related to Radian measure. Therefore, Omega is equal to so many radians per second. It is the time rate of change in angular displacement. This is equal to the distance traveled by the conductor, which is measured in radians, divided by the period (T), time taken for one revolution". So did the Zodiac Killer use the uppercase Omega sign as a subtle clue to "radians", bearing in mind the Z32 was comprised of uppercase letters?    

Therefore, if we go with the hunch that the "radians" word begins on the Omega part of the code (see above), how likely is it that "radians and five inches" would perfectly complete the Z32 code from character 13 to character 32. All we have to do then is add the word "four" before "radians" to complete characters 9 to 12, thereby creating "four radians and five inches" (from character 9 to character 32). Then we have to fill in the three repeating ciphertext characters with the plaintext characters of E, S and A. The answer of "estimate" is now fairly obvious, bearing in mind the target chosen by the Zodiac Killer was extremely unlikely to have fell on an exact amount of radians and inches. It could be argued that the Zodiac Killer gave us the three repeating ciphertext characters within the word "estimate", to give us a chance at uncovering the final part of the solution. The rest of the solution he had already given us in the phrase "The Mt. Diablo Code concerns Radians & # inches along the radians".."The Mt. Diablo Code concerns (FOUR) RADIANS & # (FIVE) INCHES along the radians".

Despite this concept being obvious once presented, the idea was undoubtedly a brilliant discovery by Zodiac researcher, Druzer, who unfortunately will never get the credit he deserves. This discovery, while incredibly easy to present, required somebody of the caliber of Druzer to unearth the answer. The simplicity of this solution is its strength, when compared to the fantastical and convoluted presentations you will encounter throughout the internet. Did the Zodiac Killer just read this information from the various publications that came his way, or did he have an intrinsic knowledge of electrical circuitry, so enabling him to create fully functioning bomb-making diagrams?           ​

In 2020, the Zodiac Killer's 32 character code was solved by Druzer, who put forth the answer of "Estimate Four Radians and Five Inches". The Zodiac Killer, knowing the code was unsolvable with only three repeating characters, pretty much gave us the answer on July 26th 1970, when he wrote "PS. The Mt. Diablo Code concerns Radians & # inches along the radians". The "code concerns Radians & # inches" meant using "radians and inches" in the answer, with the hashtag key the obvious giveaway.

Once "four radians and five inches" was placed in the code from character 9 to 32, only the word "estimate" satisfied the three repeating ciphertext characters in the 1 to 8 position in the code. The four radians and magnetic north of 246.2 degrees (229.2 + 17 degrees), fell slightly shy of Ingleside Police Station (SFPD), which was the target highlighted by the black circle within the crosshairs. You may come across a disingenuous individual cloaking his identity under the pseudonym of VT Squire, who insists that I manipulated the overlays to achieve a preconceived and desired result. However, as you can see in the 2020 article linked above, the accuracy was never exact. Four radians and magnetic north measured 246.2 degrees, while Ingleside Police Station sat at 251 degrees. Manipulating the overlays to produce an exact result would completely negate the point of having "estimate" in the Z32 code. 

​The Zodiac Killer once again used radians in his Bus Bomb letter approximately 7 1/2 months earlier (November 9th 1969), when he threatened to target Salesian High School (likely with a bomb). The crosshairs he provided in this instance, highlighted the numbers 6, 8, 9, 10 and 11 on a clock face, which when tilted close to magnetic north in 1970 and centered over Mount Diablo, landed over the five attack sites he was claiming at Lake Herman Road & Blue Rock Springs (line 10), Lake Beryessa (line 11), Presidio Heights (line 8) and San Jose (line 6). See below. The Zodiac Killer falsely claimed the murders of Snoozy & Furlong in San Jose a day earlier in his Dripping Pen card. Only line 9 remained unanswered. Next to his crude crosshairs "clock face", shown here, he wrote "PS. Be Shure to print the part I marked out on page 3 or I shall do my thing". His "thing" seemed to be the targeting of schoolchildren, so it wasn't surprising that line 9 fell over the Salesian High School where Daniel Williams worked as a school teacher. Daniel Williams had received numerous threats from somebody identifying themself as the Zodiac Killer in the preceding weeks.

One has to remember when looking at the crosshairs on the Bus Bomb letter (and Little List letter), that these are crude designs not meant to be totally accurate. The 9 o' clock position is 270 degrees on a compass rose, therefore, 9 o' clock and magnetic north (of 17 degrees) is 287 degrees. One radian is approximately 57.3 degrees, so 5 radians is 286.5 degrees. Therefore, 5 radians equals line 9 tilted to magnetic north.

With the crosshairs "clock face" tilted close to magnetic north, line 9 falls over the Salesian High School.(9 o' clock position). Not only did somebody identifying as the Zodiac Killer target Daniel Williams with arsenic on November 2nd 1969, but the school where he worked was also targeted on November 9th 1969 by the Zodiac Killer, using a measurement of 5 radians. That's because the Zodiac Killer was responsible for both. The Zodiac Killer did exactly the same thing on June 26th 1970 (Button letter), when he used 4 radians to target the San Francisco Police Department (SFPD) with a bomb. On both the Phillips 66 map (mailed with the Button letter) and the Bus Bomb letter, the Zodiac Killer utilized the numbers on a clock face. In both instances, the 9 o' clock position has to be rotated clockwise by magnetic north to identify the target.

USING MOUNT DIABLO ON NOVEMBER 9TH 1969

Many people believe (but not everyone) that the Zodiac Killer paraphrased the wording from Groucho Marx's version of The Mikado into his Little List letter on July 26th 1970. The Groucho Marx connection would reappear in a possible Zodiac Killer communication in 1990, when a Christmas card was mailed to the San Francisco Chronicle from Eureka. The designer of the card was George Schill, a contract artist with the American Greetings Card Company (Corporation) for 38 years, who informed me that all the imagery on the card (including the snowman) is exactly as he created it. In other words, nothing was added to the card outer by the Zodiac Killer. So, if the Eureka card was mailed by the Zodiac Killer, why did he choose to resurrect a connection to Groucho Marx after 20 years? (assuming the original connection was correct). If the image design on the Christmas card was chosen specifically, what could have triggered this choice?

The Zodiac Killer appeared to commemorate anniversaries and dates, such as the Lake Herman Road murders and Melvin Belli letter on December 20th 1968 and 1969 (possibly with the release date of the 1965 movie The 10th Victim). He mailed the Pines card on March 22nd 1971 referring to the abduction of the missing Donna Lass, exactly one year after the abduction of Kathleen Johns on Highway 132. He mailed the 1987 "Halloween" letter seventeen years after the 1970 Halloween card. The March 13th 1971 "Los Angeles" letter was mailed on the US release date of the Vanishing Point movie, which used the same language as the letter in its January trailer..The August 1st 1973 "Albany" letter was mailed in response to a recent newspaper article that featured the date of August 1st 1969, by mentioning the receipt of the Zodiac Killer's first three letters and cryptograms. The "Albany" letter also carried another cryptic offering. One could argue that these are just coincidental. But if they were not, what anniverary or date could have inspired the Zodiac Killer to select a Groucho Marx Christmas card in 1990, which he may have had to source in advance to ensure his selected choice.   

Although Groucho Marx died on August 19th 1977, the year 1990 commemorated the 100th year of Groucho Marx's birth on October 2nd 1890. This was featured in many American newspapers in the run up to Christmas, with a flurry of Groucho Marx movies gracing the television screens as a mark of respect. Was this an anniversary noted by the Zodiac Killer, who decided to feature the comedian and actor on his Christmas greeting card, twenty years subsequent to the Little List letter that many believe was plagiariized from a Groucho Marx recital of The Mikado.   

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 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 and believed it to be satanic, wanting 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, except for 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 extremely close to 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.

It is unlikely that the punched hole in the top right corner of the Pines card can be used to find the burial location of Donna Lass, because the Zodiac Killer has provided no evidence he had any involvement in her murder. The vague and cryptic phrases pasted on the Pines card could just have been designed to identify the name of Donna. When the "Sierra Club" on the postcard is aligned over the Sierra Club of Clair Tappaan Lodge, the punched hole can be aligned over the "Donner" of the Donner Memorial State Park. This notion carries a little more weight when we consider a similar pasted card, dubbed the Monticello card, that 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 very likely 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.