The Zodiac Killer's 38 character code may be solved by examining three of his other ciphers (two solved and one unsolved), including the day he mailed the first Fairfield letter in December. The Z340 (November 8th 1969), Z38 (December 7th 1969), Z13 (April 20th 1970) and Z148 (probably May 3rd 1971) all have one other date in common - October 22nd 1969.

[1] The Z340 (November 8th 1969) was a response to the October 22nd 1969 Jim Dunbar Show, stating that the person who phoned into the show was effectively an imposter or phony, encoding a contemporary message and using wording similar to the headlines in the San Francisco Chronicle on October 24th 1969. The 340 message read, in part "That wasn't me on the TV Show", mimicking the headlines of "That Wasn't Zodiac, Say 3 Who Know" and "It Wasn't Zodiac, Say 3 Who Know". He also responded to the Jim Dunbar Show and the October 23rd 1969 Chronicle article, entitled "A TV Runaround With Zodiac Calls", in which "Belli told Sam he'd attempt to get a promise from District Attorney John J. Ferdon that Zodiac would be spared the gas chamber if convicted of murder". The Zodiac Killer responded in code that he was "not afraid of the gas chamber".​ 

​[2] The Z148 code (probably mailed May 3rd 1971) was again contemporary in nature, and a response to the police arrest and interview of Karl Francis Werner on April 29th 1971. Three newspaper articles ran with the headlines "San Jose Student Held in Slaying of Three Girls", "San Jose Student Held in Slaying of 3 Girls" and "Youth Arraigned in Knife Slayings of Three Girls". The Zodiac Killer encoded these headlines in his 148 character cipher by promising to "skin three kids and make a suit from the skin" if his latest letter was not published. He also encoded the statement "stop listening to phonys" in the Z148, referring to both Karl Francis Werner (who was being interviewed for the Snoozy & Furlong murders on August 3rd 1969, to which the Zodiac Killer had already claimed as his victims) and Eric Weill (who phoned into the Jim Dunbar Show at least twice, claiming to be Zodiac}. The second phone call was reported in San Francisco Chronicle on February 6th 1970, entitled "Talk Show's 'Zodiac' Caller a Phony", with Inspector David Toschi pitching in: "Homicide detectives later listened to a tape recording of the conversation and concluded that Sam was a phony. It most certainly was not Zodiac, said Inspector David Toschi".  The headlines of the October 24th 1969 and February 6th 1970 Chronicle articles both placed within the encoded text of the Z340 and Z148.

[3] The Zodiac Killer mailed the Z13 on April 20th 1970, very likely a response to the October 22nd 1969 article in the San Francisco Examiner, entitled "Cipher Expert Dares Zodiac to Tell Name". It read "Dr Marsh told the Examiner today: The killer wouldn't dare, as he claimed in letters to the newspapers, to reveal his name in the cipher to established cryptogram experts. He knows, to quote Edgar Allen Poe, that any cipher created by man can be solved by man. Zodiac has not told the truth in his cipher messages to the Examiner, the Chronicle and the Vallejo Times-Herald. Zodiac has not done this, because to tell the complete truth in relation to his name-in cipher code-would lead to his capture. I invite Zodiac to send The American Cryptogram Association a cipher code, which will truly and honestly include his name". The Zodiac responded on April 20th 1970 by stating "This is the Zodiac speaking. By the way have you cracked the last cipher I sent you? My name is___ " The letters N, A, M and E could be found in the ciphertext of the code.

[4] The Z38 mailed on December 7th 1969 began with "This is the Zodiac speaking. I just need help", mimicking the caller (Eric Weill) to the Jim Dunbar Show on October 22nd 1969. It is clear that this cry for help was a disingenuous attempt at ridicule from a killer who either listened to the Jim Dunbar Show on October 22nd 1969, or read the subsequent newspaper articles. On October 22nd 1969, the Los Angeles Times reported that "Belli was put on the line, and the voice said "I want help". On October 23rd 1969, the Desert Sun newspaper claimed that Melvin Belli told the caller “All of San Francisco wants to help you. The hand is out, you can feel the hands out.” On the same day of December 7th 1969, we have a man mailing a letter to the San Francisco Chronicle mocking the call to the Jim Dunbar Show by stating "I just need help", followed a few hours later by a call to an Oklahoma radio station by a man doing an awfully good impression of the man who rang the Jim Dunbar Show on October 22nd 1969. This impressionist caller could possibly be the Zodiac Killer mocking the Jim Dunbar Show, just as he had done in the letter earlier that day.

​Therefore, we have the Z340 (November 8th 1969), Z38 (December 7th 1969), Z13 (April 20th 1970) and Z148 (probably May 3rd 1971), all relevant to the date of October 22nd 1969. Bearing in mind the Z38 carried the same four and five characters from the beginning and the end of the 340 cipher, along with the observations above, we could expect the Z38 message to be somehow related to these other ciphers. The message may very well lie in the newspaper inches from October 22nd 1969 to December 7th 1969 - and may be related to the Jim Dunbar TV Show yet again. 

The Zodiac Killer is allowed to produce handwriting in subsequent letters the same or similar to previous communications because he is effectively doing no more than mimicking himself. A copycat or hoaxer can mimic the Zodiac Killer using previously published letters and envelopes in the newspapers, but what they cannot do is mimic unreleased communications by the Zodiac Killer. To my knowledge, only two envelopes were released to the newspapers prior to January 29th 1974 that were addressed to San Francisco. The envelope to the Melvin Belli letter was released on December 28th 1969 with the address of "Mr. Melvin M. Belli 1228 Mtgy San Fran Calif". The envelope to the 340 cipher was released on November 16th 1970 with the address of "S.F. Chronicle San Francisco Calif Please Rush to Editor".  The author of the Exorcist letter (if a hoaxer) when addressing their envelope to the San Francisco Chronicle only had these two envelopes to work with, but copied neither. This mimicry would have been expected of a hoaxer.  

Instead, the author of the Exorcist letter chose to mimic part of the address from two envelopes mailed by the Zodiac Killer in April 1970. These two envelopes were addressed San Fran (dot) Chronicle on April 20th and April 28th 1970 and never publicly released via the newspapers prior to January 29th 1974. When you look at the April 28th 1970 envelope in particular, it isn't just the handwriting that is extremely similar, it's the positioning of the detached full-stop, the spacing between each of the three components, the very slight left to right slant, the marginally elevated letter L, the letter I is dotted directly above in every instance, and both the letters R and H are slightly separated. The April 20th and April 28th envelopes were the only two Zodiac communications up to January 29th 1974 that were addressed in this fashion, yet the author of the Exorcist letter (if a hoaxer) would have managed to virtually replicate every facet of this address despite having never laid eyes on them. This clearly shows that the Exorcist letter author was the Zodiac Killer, putting to rest any notion that this letter may have been fraudulent.     

People will say this just further proves that the Exorcist letter was penned by Inspector David Toschi, who had inside knowledge of the two April 1970 letters. Why would Inspector David Toschi copy the address so perfectly from an envelope that had never been released into the public domain by January 29th 1974, thereby drawing suspicion towards somebody from within? He was an intelligent seasoned investigator, not an imbecile. The exact same reasoning can be applied to the 1978 letter when comparing the opening line from each communication. A copycat or investigator would apply logic, and mimic the widely publicized "This is the Zodiac speaking" introduction displayed in four San Francisco Chronicle publications (or mimic the 11 out of the 12 communications prior to January 29th 1974 that carried this introduction), not mimic an introduction never released into the public domain such as "This is the Zodiac speaking I" in the Melvin Belli letter. However, the Zodiac Killer is perfectly allowed to be himself.   

Based on Mike Rodelli's book and everything he has stated over the last few years, we should today have the ability to either incriminate or exclude Kjell Qvale as the Zodiac Killer.once and for all. According to Alan Keel, Criminalist at the San Francisco Police Department, San Francisco, California from 1996 to 1999, he "revealed that there were two letters in possession of the department that, in contrast to the "true" Zodiac letters, had abundant saliva and DNA-containing oral epithelial cells on them, that DNA was easily extracted from these two letters, and that the DNA extracted from these two letters matched between them. These two letters were considered forgeries, since the "true" Zodiac verifiable letters had not been licked by the sender". According to Mike, Alan Keel had "analyzed two letters, one of which is the 1978 'forgery', and finds that this letter and one of the 1974 letters are loaded with saliva and cells. He then easily extracts DNA from both of these letters using the more primitive DNA technology of that time and finds that the DNA matches between those two letters, thus proving that one person sent both". The only problem with the statements by Alan Keel is that the 1978 letter is unlikely to be a forgery. 

On October 29th 2021, Mike Rodelli stated on the Zodiac Killer message board "The fact remains that in 2007 Keel told me, as he had told Lafferty before me, that there is a 1974 forgery based on DNA and the ONLY 1974 letter that had been tested for the presence of cells during Keel's tenure (as demonstrated by the DNA chart that I believe Keel made in about 2000) was the Exorcist letter. This is not rocket science.  Even if it is not the Exorcist letter that Keel was talking about, it IS a candidate as being a forgery whose DNA matches the 1978 letter based on the information in the chart". Mike Rodelli is correct. The only communication from 1974 that can conceivably match the DNA from the 1978 letter is the Exorcist letter. Mike also stated on the Zodiac Killer Net forum "This is where the rubber truly meets the road in this discussion and where we can see that it is unlikely that anyone but Zodiac wrote the SLA letter. When you look at the hand printing on the SLA letter in a vacuum, it certainly does not jump off the page to me that it was penned by Zodiac. But when you take a close look at the envelope, that is a different story". Mike then shows comparisons between the SLA envelope and the Stine envelope, 340 envelope, Bus Bomb envelope and Kathleen Johns envelope, arguing "It's hard to look at these envelopes and not see the similarities. And note that the November 8, 1969 envelope contained a piece of Stine's shirt, thus proving its authorship as being from Zodiac".       

Therefore, if Mike Rodelli is being fair-minded and believes the SLA handwriting is consistent with these other communications, then he should have no argument conceding that the handwriting and construction of the Exorcist envelope handwriting is consistent with the envelopes from April 20th 1970 and April 28th 1970, which he believes are Zodiac communications. Mike should therefore come to the same conclusion, that since the two April 1970 envelopes were the Zodiac Killer, then so is the Exorcist letter. The April 1970 communications were the only two confirmed Zodiac envelopes to carry the address of San Fran (dot) Chronicle prior to January 29th 1974. The envelopes were also never released into the public domain, meaning the Exorcist letter author could not have mimicked them.       

Mike should now agree that having established the Exorcist letter as genuine Zodiac material - and using the findings of Alan Keel and Mike's correct argument that the 1978 DNA should conceivably match the Exorcist letter DNA (being the only ones tested in the DNA chart) - we have to conclude that the 1978 letter is genuine as well. Mike went on to say on the Zodiac Killer message board "Keel further allowed, although not in this email but in a conversation I had with him at about the same time, that there was so little saliva on the Zodiac letters that it would not be unfair to say that they had been sealed with tap water and the stamps applied with tap water. So if you're wondering why after 20 years we still don't have a verified sample of Zodiac's DNA it's because the only DNA he may have left on these letters is from when he applied the stamps to the envelopes. If he wet the stamps with water but didn't wear gloves then as he applied the stamps to the envelopes the glue could have pulled a few odd cells off of the tips of his fingers thus leaving essentially touch DNA on the stamps. That is why if they do have Zodiac's DNA today it is because of this minute number of cells that they have had to find using the most Advanced Techniques available".

The argument being that the "true Zodiac letters" had few cells, whereas the fraudulent Zodiac letters had "had abundant saliva and DNA-containing oral epithelial cells". However, we have now established that the Exorcist letter is genuine, just like the two April 1970 communications. Yet these two envelopes have few cells found in the DNA chart, whereas the Exorcist letter has abundant cells, despite one author throughout. This disproves the contention of Alan Keel that the 1978 letter is a forgery, that matches one of the 1974 communications. All it proves is that the Zodiac Killer authored the 1978 letter and one of the 1974 communications. These findings also disprove the notion that the Zodiac Killer didn't lick his envelopes and/or stamps. The only way to argue the findings presented above, is to claim that there is unfounded similarity between the Exorcist envelope handwriting and the two April 1970 envelopes, while simultaneously claiming there is a similarity between the SLA envelope and the Stine envelope, 340 envelope, Bus Bomb envelope and Kathleen Johns envelope, But this would be an argument in bad faith.

The DNA chart stating that a "DNA sample was obtained" from the 1978 letter appears to back up Mike Rodelli's statement of this letter producing enough DNA to create a profile, based on the findings of Alan Keel. This being the case, if the profile of the 1978 letter matches the profile of the Exorcist letter, then we have a full DNA profile of the Zodiac Killer. Forensic genetic genealogy can now be used to discover the ancestry of the killer and ultimately identify him, in similar fashion to that used in the case of the Golden State Killer, resulting in Joseph James DeAngelo,Jr. pleading guilty to thirteen counts of murder on June 29th 2020 

FOLLOW UP ARTICLE: WE MAY ALREADY HAVE ZODIAC DNA   

On Tuesday, April 21st 1970, the San Francisco Chronicle ran an article entitled The Bloody Satan Murder stating "An autopsy yesterday morning showed Salem was slain sometime last Wednesday", which was April 15th 1970. The introduction to the article highlighted the murder of Robert Michael Salem in his 745 Stevenson Street, San Francisco apartment, describing the "macabre mutilation of the renowned lighting designer" found Sunday evening (April 19th). On Monday, April 20th 1970, the San Francisco Chronicle produced their first article on the murder, stating "A bizarre murder - with the words Satan Saves Zodiac written in blood on the expensively decorated hippie-style pad - was discovered last night at 745 Stevenson Street". The pseudonym "Zodiac" and the drawing of a religious Ankh was also found scrawled in blood on the apartment wall. It is clear, that despite Robert Salem being murdered on April 15th 1970 (or thereabouts), his murder was not discovered until Sunday, April 19th 1970. The story not released publicly until it appeared the following morning in the San Francisco Chronicle newspaper.

If the Zodiac Killer was not the murderer of Robert Salem - and didn't have inside knowledge of the discovery on April 19th - the first time he would have become aware of his pseudonym being found at a murder scene was when he bought his morning newspaper on April 20th 1970. The very same day, a letter arrived at the San Francisco Chronicle stating "PS I hope you have fun trying to fiygure out who I killed" and "I have killed ten people to date". After four months of not writing, was the timing of this letter really a coincidence - falling on the same day his bloody pseudonym was reported on the wall of a murder victim. The Zodiac Killer could easily have just written the victim count once, next to his crosshairs, but specifically added "I have killed ten people to date", suggesting that we should include the month of April into the equation. The Zodiac Killer was seemingly attempting to push us into concluding he was the murderer of Robert Michael Salem. By including a short code of thirteen characters, which included the three number eights (Christ the Redeemer in Christian numerology, and the opposing value of 666, the number of the beast), was the phrase of "I hope you have fun trying to fiygure out who I killed" trying to lead us to "Satan Saves" on the wall of the apartment?                    

What is crucial here, is the timing of this Zodiac communication in relation to the newspaper article reporting the murder of Robert Salem. If the letter was insinuating he was responsible for the 745 Stevenson Street murder, then after reading the San Francisco Chronicle on Monday, April 20th 1970, the Zodiac Killer would have had to access (or buy) his writing paper, envelopes and stamps - create a thirteen character code, recall the Officer Brian McDonnell murder on February 16th 1970, compose the letter and draw his "string of bombs" diagram almost immediately - before mailing the letter in time for it still to be collected, processed and postmarked AM on the morning of Monday, April 20th 1970 (before noon),. Is that a reasonable proposition? If this were the case, it could imply that the 13-Symbol cipher was created with no forethought, was contemporary in nature and possibly related to the murder of Robert Salem (hence the numbers).

The alternative could be that the April 20th 1970 letter was created in advance of the San Francisco Chronicle article reporting the murder of Robert Salem. This could mean that the Zodiac Killer knew of the murder prior to the details being released in the newspaper, because he was the murderer of Robert Salem at 745 Stevenson Street. It just depends on what credence you place on the timing of this letter and the emphasis you place on "I have killed ten people to date" to mean "I have killed ten people to April 20th 1970", thereby highlighting the importance of April to the victim count.

Professor D.C.B. Marsh told the San Francisco Examiner on October 22nd 1969: "The killer wouldn't dare, as he claimed in letters to the newspapers, to reveal his name in the cipher to established cryptogram experts. He knows, to quote Edgar 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".

​The Zodiac Killer responded on November 8th 1969 by using the scytale method of decryption featured at the top of Poe's essay A Few Words On Secret Writing. Or should I say, it can be used to crack the 340 cipher encrypted message, that contained the wording "one in paradice" just like Edgar Allen Poe's poem to his dead wife entitled "To One In Paradise". The next method of encryption in Poe's A Few Words On Secret Writing involved splitting the alphabet A to M and N to Z (two sections of thirteen) mirroring the Zodiac's 13 character code which began with A and ended with M - and because of the distinct lack of characters in this code - it has been considered unsolvable using standard cryptographic methods.

​The Zodiac seemingly didn't supply us with a key to this code in later communications, leading me to believe that the key or answer lies in the Edgar Allen Poe essay mentioned above. I believe the answer to the code is ​"This is the Zodiac speaking. By the way have you cracked the last cipher I sent you? My name is....Fk, I'm crackproof, in which each element of the phrase is begun by each of the circled eights, thereby creating an infinite circular cipher (hence the circled 8's which represent infinity and a new beginning). The Zodiac Killer may have supplied us with the answer to the Z13 code in the 13-Hole postcard on October 5th 1970 in which he configured the punched holes in an arrangement of 10 to 3, pinpointing the position of the three eights, and supplying the answer of Fk, I'm crackproof. Using Edgar Allen Poe's reasoning in A Few Words On Secret Writing, I can now place five letters in the correct position within the 13 character code, albeit not to my complete satisfaction.  

Here is a section of reasoning from Edgar Allen Poe's A Few Words On Secret Writing where A can represent N and vice versa, where B can represent O and vice versa, and where C can represent P and vice versa. But he also makes a point of saying A might stand for P (or vice vera). This is where I shall jump into the code using a trial and error approach. 

If A can stand for P, I shall place P above the A in the beginning of the Z13 code like so:

If A can stand for P, and P can also represent C, then A can also stand for C. So let us insert the letter C above A in the Z13 code.

If A can represent N and vice versa, B can represent O and vice versa, and C can represent P and vice versa, then E can represented R. So let us place R in the Z13 code.

Edgar Allen Poe stated that N can represent A, so let us place A above the second N in the Z13 code:

If A can stand for P, and P can also represent C, then A can also stand for C. This means that if M can stand for X, and X can represent K, then M can also stand for K (just like A stood for C). So let us insert K into the Z13 code:

If the K and M between the three eights are representative of themselves as I have previously surmised, then we have the beginning of the answer to the Z13 code. But without this assumption, we have five letters inserted that mirror the previous solution I have suggested - all reasoned from Edgar Allen Poe's essay. It's not perfect, but it's a start.

Just over two weeks before the 340 cipher was mailed, Dr. D.C.B. Marsh of the American Cryptogram Association laid down a challenge to the Zodiac in the newspapers to reveal his name in a cipher, however complicated. The wording in the San Francisco Examiner on October 22nd 1969 invoked the name of Edgar Allan Poe, so possibly the designers of the article were hoping that the Zodiac Killer would invoke Edgar Allan Poe to give us his name, making any offering easier to crack. This appeared to influence the Zodiac Killer, because the first cipher mentioned in Poe's essay A Few Words on Secret Writing actually works in decoding the message in the 340 cipher. The second cipher technique in Poe's essay A Few Words on Secret Writing split the alphabet into two portions of 13 letters, so it was surprising that the Zodiac Killer's next code reduced dramatically to 13 characters just like Poe's design (beginning with A and ending with M). See here for essay.

Three years ago, it was suggested that the Zodiac Killer wouldn't again shy away from the challenge of giving us his name, having possibly given us it in an abbreviated format. That is why the cryptic reference of Fk, I'm crackproof caught my eye in the October 5th 1970 communication with 13 punch-holes in the fabric of the card. The punch-holes were separated into a 10 to 3 configuration, positioned in such a way that they mirrored the design of the 13-Symbol cipher. The only way to break the small code was to discover the entry point, and the three circled 8's seemed as good a place as any, especially when we consider Fk, I'm crackproof is split into three parts and fits around the existing K and M in the code. The crosshairs, anchor and Celtic Cross in the code are all religious symbols, with the number 8 representing rebirth, regeneration and a new beginning in Christianity. The figure 888 is also representative of Jesus Christ in Christian numerology. It was discovered that the first 8 began FK, the second 8 began IM and the third 8 began CRACKPROOF, which completed the circle of eternal life. The introduction to the April 20th 1970 letter was also completed, to "This is the Zodiac speaking. By the way have you cracked the last cipher I sent you? My name is Fk, I'm crackproof",

Anyway, this is to show that the Fk, I'm crackproof solution was found before the 340 cipher was cracked by Dave Oranchak, Sam Blake and Jarl Van Eycke on December 3rd 2020, along with its scytale links to Edgar Allan Poe's A Few Words on Secret Writing. This is extremely important when we consider the following. Edgar Allan Poe highlighted certain encipherment techniques in the essay regarding a split alphabet, which are outlined here: and, so placed, a might stand for n and n for a, o for b and b for o, &c. &c. This, again, having an air of regularity which might be fathomed, the key alphabet might be constructed absolutely at random. The next line was: Thus A might stand for P.

These examples can be summarized as;
[1] a might stand for n and n for a
[2] Therefore, r might stand for e and e for r
[3] Thus, a might stand for p (and vice-versa)
Using only these examples in the 13-Symbol cipher, I inserted the possibilities into the code, using the letters K and M as entry points, based on the aforementioned reasoning. The letters N, A and M (not boxed in blue) I have no explanation for. So the search goes on to discover whether the Zodiac applied something else to the encryption. Or whether a different technique was used entirely.

When you take into consideration that the Fk, I'm crackproof solution was suggested in 2017, before the scytale link of the 340 cipher to Edgar Allan Poe, coupled with the formation above using just Poe's examples shown in [1], [2] and [3], it shows a pattern receptive to the remaining letters in the solution. But the three remaining ciphertext characters would need explaining. 

The next encipherment technique described in A Few Words on Secret Writing were the two concentric circles (one fixed), where the outer wheel can be rotated around the inner wheel during the coding process. Here is a working cipher wheel.

On October 22nd 1969, Dr. D.C.B Marsh in alliance with investigators and the San Francisco Examiner, attempted to refocus the Zodiac Killer's attention toward creating a second major cryptogram and "reveal his name in the cipher to established cryptogram experts". Marsh would continue to press the killer throughout the article, stating "I invite Zodiac to send to The American Cryptogram Association a cipher code - however complicated - which will truly and honestly include his name". However, in order to crack any cipher the killer may send, it would have been wise to place certain triggers within the article to guide the Zodiac Killer into choosing a particular cryptographic technique. This may have been the purpose of dropping the name Edgar Allan Poe into the San Francisco Examiner article, thereby influencing the killer to choose a cryptographic technique highlighted by Poe in one of his essays. If the Zodiac Killer then responds with a second cipher, your first port of call would obviously be Edgar Allan Poe.

Although Dave Oranchak doesn't believe the Zodiac Killer used the scytale method of encryption in the recently decoded 340 cipher, this decryption tool does actually decode the message in the 340 cipher. If the Zodiac Killer responded to the prompt by Dr. Marsh and read Edgar Allan Poe's essay A Few Words on Secret Writing, he would have noticed that the first topic of discussion was the scytale cipher, which involves disguising a message by separation, avoiding the common left-to-right method of decryption. This is what the Zodiac Killer used in his 340 cipher. In further reading of A Few Words on Secret Writing, it became apparent that other encryption methods were discussed in addition to the scytale method, with the possibility existing that the Zodiac Killer may have adopted one of these techniques for his following 13-Symbol cipher on April 20th 1970. The most notable encryption methods discussed included separating the alphabet A to M, and N to Z, into two equal parts of 13 letters. This involved placing the alphabet into the following configuration.

Here is an excerpt from Edgar Allan Poe's A Few Words on Secret Writing: and, so placed, a might stand for n and n for a, o for b and b for o, &c. &c. This, again, having an air of regularity which might be fathomed, the key alphabet might be constructed absolutely at random. The next line was: Thus A might stand for P.

If we then represent the second ciphertext character N (11th position} with the plaintext character A shown in Poe's writing, we get the diagram shown below, with the circular Fk, I'm crackproof starting to emerge.

The relationship  between the remaining ciphertext characters of N, A and M, to the plaintext characters in the solution of O, C and K respectively, can be seen in the diagram below. These are never more than two apart in the alphabet. This is a work in progress.

The discovery of the message in the 340 cipher has triggered a new debate on the intelligence of the Zodiac Killer, bearing in mind the greater complexity of the encryption used to disguise its contents. Creating an extremely difficult cipher is actually far easier than attempting to decode it, especially when the person who designs the cipher accidentally bakes errors into his cipher as shown by the Zodiac Killer.

However, Cragle on the Zodiac Killer Site forum made an astute observation regarding the Zodiac Killer's switch from describing his hidden messages as ciphers, to codes in the June 26th 1970 and July 26th 1970 letters. While not completely true, because the Zodiac Killer stated "By the way, are the police having a good time with the code?" on August 4th 1969, it does open up the broader point of the difference between codes and ciphers, which is effectively what Cragle was implying. Codes generally operate on semantics, while ciphers operate on syntax. A cipher is a system to make a word or message secret by changing or rearranging the letters in the message, whereas a code is a system of changing entire words or phrases into something else. Codes are not just secret messages, they can be any symbol or signal used to represent, or communicate, something else.

One could argue, that if the Zodiac Killer invested the time to construct a period nineteen cipher, then he was certainly aware that by creating the Z13 and Z32  codes of such brevity and variability, he was effectively creating an impossible task and any realistic possibility of a solution without ultimately providing a key to each code. The fact that the Mount Diablo code had 29 unique characters in a 32 character array, makes it practically unsolvable without that key, A key explaining these 29 unique characters in his remaining communications appears not to be the case. The Zodiac Killer stated that "the map coupled with the code will tell you where the bomb is set", so if we take this literally, then the Zodiac Killer by June 26th 1970 expected us to solve the 32 character code with nothing more than the Phillips 66 map he supplied alongside the letter. He did supply additional clues on July 26th 1970 in the form of "P.S. The Mt. Diablo code concerns Radians + # inches along the radians", but as of June 26th 1970 he fully expected us to decipher these 29 unique characters with nothing more than a map, lending credence to the notion that this encryption was designed as a code rather than a cipher. Finding corresponding alphabetical letters to 29 unique characters appears an unlikely proposition with the limited information he provided. A man with the patience to design the 340 cipher encryption must have known this.

Sam Blake, who contributed to the solving of the 340 cipher, made an extremely valid point when stating that the decoded message was contemporary. By the Zodiac Killer claiming that "it wasn't me on the TV show", he fully expected his 340 cipher to be decoded fairly quickly. This message was for the moment, not for 51 years later. The same is probably true for the Z13 and Z32. These codes were apparently designed with the promise of a hidden name and bomb at a time when newspapers were king. When the Zodiac Killer started fading from the newspaper headlines by 1971, the ongoing quest to decipher these two codes had equally faded into obscurity. This isn't the case today, with the internet endlessly keeping the mystery and speculation alive. But as the 1970s rolled forward these codes would have faded from the publics gaze, making these puzzles much more contemporary at the time they were designed. The Zodiac Killer could enjoy the speculation surrounding his unsolved puzzles and codes while they were still being discussed in the newspapers, but once the San Francisco Chronicle and San Francisco Examiner have moved away from featuring the Zodiac Killer, the feedback surrounding his unsolved codes would equally fade away. He probably expected these two codes to remain unbroken for a limited time only.

Therefore, as Cragle intimated, we might be better rewarded by looking at the Z13 and Z32 codes through the lens of codes rather than ciphers. The search for words or phrases, in accompaniment to the limited clues he supplied, quite possibly a much more profitable avenue to go down. The solving of the 340 cipher has inevitably switched the focus of attention toward the remaining unbroken codes, with every effort being made to follow up on the success of Dave Oranchak, Sam Blake and Jarl Van Eycke. However, adopting an approach using cipher-type encryption may possibly lead to another 51 years of blind alleyways and false beliefs, scattered with the graveyards of "solved solutions" that never were.

After two Zodiac attacks in close succession on September 27th 1969 and October 11th 1969, investigators must have feared an escalation in terror from the Bay Area murderer, so it would have certainly been in their interests to switch the Zodiac Killer's attention to communication instead of murder. On October 22nd 1969, Dr. D.C.B Marsh in alliance with investigators and the San Francisco Examiner, attempted to refocus the Zodiac Killer's attention toward creating a second major cryptogram and "reveal his name in the cipher to established cryptogram experts". Marsh would continue to press the killer throughout the article, stating "I invite Zodiac to send to The American Cryptogram Association a cipher code - however complicated - which will truly and honestly include his name". However, in order to crack any cipher the killer may send, it would have been wise to place certain triggers within the article to guide the Zodiac Killer into choosing a particular cryptographic technique. This may have been the purpose of dropping the name Edgar Allan Poe into the San Francisco Examiner article, thereby influencing the killer to choose a cryptographic technique highlighted by Poe in one of his essays. If the Zodiac Killer then responds with a second cipher, your first port of call would obviously be Edgar Allan Poe.

Although Dave Oranchak doesn't believe the Zodiac Killer used the scytale method of encryption in the recently decoded 340 cipher, this decryption tool does actually decode the message in the 340 cipher. If the Zodiac Killer responded to the prompt by Dr. Marsh and read Edgar Allan Poe's essay A Few Words on Secret Writing, he would have noticed that the first topic of discussion was the scytale cipher, which involves disguising a message by separation, avoiding the common left-to-right method of decryption. This is what the Zodiac Killer used in his 340 cipher. In further reading of A Few Words on Secret Writing, it became apparent that other encryption methods were discussed in addition to the scytale method, with the possibility existing that the Zodiac Killer may have adopted one of these techniques for his following 13-Symbol cipher on April 20th 1970. The most notable encryption methods discussed included separating the alphabet A to M, and N to Z, into two equal parts of 13 letters. Followed by a technique involving two concentric discs, akin to the Union Cipher Disk that held the number configurations of 000 and 888. These techniques show promise when we consider the design and structure of the 13-Symbol cipher. This has been covered in a much more extensive article, so it will not be covered any further here.  

Dr. Marsh, under the banner of Cipher Expert Dares Zodiac to Tell Name, would persist throughout the article into cajoling the Zodiac Killer to reveal his name by way of a cryptogram. This is why another passage in A Few Words on Secret Writing caught my attention - and may have resonated with the Zodiac Killer too. It concerned a reader sending in cryptograms to Edgar Allan Poe, but refraining from giving his name. The passage read "This challenge has elicited but a single response, which is embraced in the following letter. The only quarrel we have with the epistle, is that its writer has declined giving us his name in full. We beg that he will take an early opportunity of doing this, and thus relieve us of the chance of that suspicion which was attached to the cryptography of the weekly journal above-mentioned–the suspicion of inditing ciphers to ourselves. The postmark of the letter is Stonington, Conn".

This reminded me of the statement by Dr. Marsh when he challenged Zodiac, who he contended "had not told the truth in his cipher messages to the Examiner, the Chronicle and the Vallejo Times-Herald". He claimed "Zodiac has not done this, because to tell the complete truth in relation to his name would lead to his capture". Did the Zodiac Killer read this passage in A Few Words on Secret Writing and get some ideas?

The reader who mailed Edgar Allan Poe from Stonington, Connecticut, failed to supply his name, but did begin by placing a letter S, followed by a horizontal dash, similar to the Zodiac Killer's introduction on April 20th 1970, The Zodiac Killer began the introduction to his 13-Symbol cipher by stating MY NAME IS ---------. The sender of the cryptograms to Poe only signed his name at the bottom of the intoductory letter by use of initials, concluding with "I am yours, respectfully S.D.L." Not wanting to shy away from the challenge of Dr. Marsh a second time, I couldn't help thinking that the Zodiac Killer may have rose to the challenge and given us the initials to his name (or fictitious initials), just like the sender of the cryptograms from Stonington, Connecticut. Another thing to note, is that Dr. Marsh laid down this challenge on October 22nd 1969, so 182 days had elapsed before the Zodiac Killer's third confirmed cryptogram arrived at the San Francisco Chronicle on April 21st 1970.

Paul Avery wrote on April 22nd 1970, in an article entitled Zodiac Sends New Letter-Claims Ten, that "the killer who calls himself Zodiac has once again written to the Chronicle. In a letter received yesterday, Zodiac claims he has killed again". This letter was received by the San Francisco Chronicle on April 21st 1970, the exact day and month the letter from Stonington, Connecticut was postmarked from the anonymous sender to Edgar Allan Poe. This all may have been coincidence, but it would certainly be worth looking for the Zodiac Killer's initials as part of the answer to the 13-Symbol cipher.

That answer could be "This is the Zodiac speaking. By the way have you cracked the last cipher I sent you? My name is Fk, I'm crackproof", given to us in the Zodiac Killer's postcard five-and-a-half months later as a big hint to its decipherment. The 340 character cipher was split into rows of 9, 9 and 2 sections. The 13-Symbol cipher may have been split into 2. 2 and 9 sections, with the circled 8's beginning each section of the phrase. The letters K and M were already in place for a perfectly circular message, as highlighted in the October 5th 1970 communication by the Zodiac Killer, in which he supplied us with the phrase Fk I'm crackproof.   

On April 20th 1970, the Zodiac Killer mailed a 13-Symbol cipher to the San Francisco Chronicle, in addition to a bus bomb diagram threatening to blow up a school bus. Let's compare the 13-Symbol cipher to the 13-Hole postcard on October 5th 1970, in which the Zodiac Killer may have completed the introduction of "My name is" to "My name is Fk, I'm crackproof", again teasing us with a less than complete resolution to his real identity.

On April 20th 1970, the Zodiac Killer made reference to the murder of San Francisco police officer Brian McDonnell (44) 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.  He wrote "I hope you do not think that I was the one who wiped out that blue meannie with a bomb at the cop station", while simultaneously giving us a diagram of a bomb to be placed just 274 feet from another "cop station", that of Ingleside. This sense of irony didn't seem lost on the Zodiac Killer. What the Zodiac Killer knew of Brian McDonnell, other than what he read in the intervening two months is unknown, but in the remainder of his short message he stated "But there is more glory in killing a cop than a cid because a cop can shoot back". Was this just an offhand comment, or was this statement relevant to the history of Sergeant Brian McDonnell?

The Desert Sun newspaper of February 17th 1970 read: Haight Ashbury Police Station Rocked By Bomb Six Officers Injured In Blast Showering Big U-Shaped Staples.

SAN FRANCISCO (UPI) - A powerful bomb packed with U-shaped staples rocked a Haight-Ashbury District police station Monday night injuring six policemen, one of them critically. New Police Chief A. Nelder said the fused explosive was placed on the rear window sill of the sergeant’s office at Park Station in Golden Gate Park. The thunderous blast, which jarred residents for blocks around, sprayed staples through the office like miniature machinegun bullets. Sgt. Brian McDonnell fell gravely wounded with multiple head injuries. Patrolmen Robert Fogerty, 43, and Frank Rath. 27, were hospitalized with multiple puncture wounds. Officers Alfred Arnaud, 24, Robert O’Sullivan, 26. and Ronald Martin, 28, were treated for lesser injuries. “All I remember was a bomb exploded,” said one shaken officer who survived with only scratches. “I saw Sergeant McDonnell lying in the rubble, bleeding from an artery wound in his neck.” Police immediately sealed off the area and rerouted traffic. First reports indicated the building had been demolished. The blast did knock out all power in the station and shattered every window. It also demolished the sergeant’s police station wagon which was parked behind the station near Kezar Stadium, where the San Francisco Forty Niners play National Football League opponents. There were reports that a man was seen running from the station, and police later said a white and pink van was sighted leaving the area. However, there were no immediate suspects. Four days ago, three cars were blown up and two reserve policemen were injured by two bombs which exploded in a parking lot adjacent to the Berkeley police station across the bay from San Francisco. The explosive used in the Berkeley bombing was a metal pipe filled with powder and set off by a lighted fuse. The type of bomb used in the bombing of the Park police station was not determined immediately. A special U.S. Army bomb squad was summoned to the scene from the Presidio nearby. After the bombing, all district police stations in San Francisco were ordered to secure all doors and exits and post a guard.

Would it be surprising the Zodiac Killer after reading and referencing the attack on Park Police Station, that he would then focus his bomb threats in close proximity to another police station on April 20th 1970 and June 26th 1970. The diagram of the bomb location on April 20th 1970, coupled with the radians and inches values from July 26th 1970, leaves little doubt that the unfortunate murder of Brian McDonnell was the catalyst for his remaining bomb threats towards Ingleside Police Station in 1970. It is also unsurprising that after reading headlines such as "Six Officers Injured in Blast Showering Big U-Shaped Staples", that the Zodiac Killer would follow up his April 20th communication with the Dragon card on April 28th 1970, writing on the front of the card "I hope you enjoy yourselves when I have my Blast". He would repeat this approach on the card inner, stating "If you don't want me to have this blast you must do two things".

The Dragon card is thought to depict the Miguel de Cervantes Saavedra characters of Don Quixote and Sancho Panza. This may have been a deliberate choice on behalf of the Zodiac Killer, as these characters were featured in statue form within Golden Gate Park, the location of Park Police Station. The two locations are about one mile from one another. Despite claiming he wasn't responsible for the Park Station bombing, he certainly wasn't averse to mocking the police at a time of immense grief. The Zodiac Killer, despite making many threats to murder by use of bomb, constantly made excuses for not doing so. On November 9th 1969 he claimed that the bomb was ready for "future use". On April 20th 1970, the problem was "I have killed ten people to date. It would have been a lot more except that my bus bomb was a dud.  I was swamped out by the rain we had a while back". On June 26th 1970 he promised to annihilate a full school bus, "but now school is out for the summer". It seemed for the Zodiac Killer the lingering threat was all that was required, pouring huge doubt on him having any serious intentions of following through on his bomb threats towards San Francisco. Knowing that the police had to take the threats seriously was satisfactory enough for a killer who thrived on instilling fear in the Bay Area community.

The Zodiac Killer mailed the Button letter on June 26th 1970 promising us that the "The Map coupled with this code will tell you where the bomb is set". Thirty days later, on July 26th 1970, he would give us the near-full answer to the 32-Symbol code, which only required the number 5 added to it (Radians and 5 inches along the radians). He also drew the dark, black circle around the circumference of a second set of crosshairs to provide the exact angle we had to travel away from Mount Diablo.  However, when he constructed the Button letter, he was of the opinion that he had provided us with enough information to solve the conundrum of where the bomb was set. This in itself was a massive clue when you consider the code had only three repeating characters. The introduction to the Button letter stated "I have become very upset with the people of San Fran Bay Area. They have not complied with my wishes for them to wear some nice Zodiac buttons. I promised to punish them by anilating a full School Buss. But now school is out for the summer, so I punished them in another way. I shot a man sitting in a parked car with a .38". It is clear that this introduction has nothing to do with the code, and in no way can be manufactured to explain the meaning behind the 29 unique characters contained with the 32-Symbol code. Therefore, the solution to the 32-Symbol code was expected of us (by Zodiac) using only what he added to the Phillips 66 map. This appears impossible - but it is not. 

Obviously, the following has only been worked out in hindsight of knowing the answer to the Mount Diablo code. This is why the Zodiac Killer gave us the two crosshairs with the answers in the Little List letter a month later - he knew that the clues he gave us on the Phillips 66 map were scarce to say the least. The Zodiac Killer gave us very little when he drew the crosshairs on the Phillips 66 map, yet he still expected us to use this to solve the 32-Symbol code. This should have been the biggest clue of them all. There is absolutely no way anybody can individually decode 29 unique characters in the 32-Symbol code by using what the Zodiac Killer drew on the map, but the crosshairs on the Mount Diablo map can be used to identify where particular words began on the 32-Symbol code, from which we can then start filling in the blanks - much like the Harden's identified the double symbols on the 408 cipher to identify "kill", therefore beginning the process of decoding. Once you get your foot in the door, eventually the whole cipher starts peeling open like an orange. This exact same process had to be adopted to unravel the 32-Symbol code using the crosshairs on the Phillips 66 map. The key was devilishly simple, but extremely unlikely to have been unearthed without the benefit of hindsight. 

To unearth the position of the bomb we have to travel a certain distance around the circumference of the circle of the crosshairs, set to Magnetic North (17 degrees in 1970). Then we had to travel a certain distance away from the summit of Mount Diablo (marked as position X by the Zodiac) from that degree point. The first thing we had to discover was his likely target area. The map was of San Francisco & Vicinity, with all the Zodiac Killer's previous letters and bomb threats focused towards San Francisco and the police. Therefore, the Zodiac Killer likely expected us to explore this avenue first. But before we do that, let's explore the limited characters contained by the crosshairs above.

To find the angle around the crosshairs we have to consider that any number of degrees could fall over San Francisco from its north to south border, with no way of determining this figure from the information supplied. So, we have to look for a way of measuring an angle around the circumference of the crosshairs where only one figure is possible for the answer. This lay in the radian, because only 4 radians and magnetic north could fall inside San Francisco (beginning from his arrow pointer, set to magnetic north and traveling around the clock face he provided). No other radian value could land inside San Francisco. We now have to focus on the diagram above. Radians would travel around the circumference of the crosshairs, so let us take a punt that the repeating C in the 32-Symbol code was representative of crosshairs/circumference, and therefore the radians that traveled around them. These would be the first two words inserted into the 32-Symbol code below. 

There are two other symbols or characters inside the crosshairs on the Phillips 66 map. The first one is the X symbol, deliberately accommodated by the Zodiac Killer by not fully completing the intersecting lines of his crosshairs. He could easily have just drawn normal crosshairs over Mount Diablo and everybody would have known this was his beginning point, yet he carefully left this area free to insert the letter X. This alphabetic letter can be found in the 32-Symbol code, so let us again assume that this is the starting point for another word. The only other character visible inside the crosshairs on the Phillips 66 map is the (in part) filled-in red triangle. We will take the same approach we did with the X symbol, and assume that the filled-in red triangle is represented on the 32-Symbol code by the filled-in black triangle (again beginning a word). The black triangle is often used to depict a mountain. We now have the C, X and black triangle in the 32-Symbol code, all of which should be the beginning of words.

Just like the degrees argument above, we know that by using miles as a measurement, any number of miles from Mount Diablo to San Francisco can fall within its eastern and western borders. Therefore, the answer cannot be in miles. But using the map code of 6.4 miles to the inch only one figure of inches can fall inside the land mass of San Francisco - and that figure is five. We also know that if the black triangle in the 32-Symbol code begins a word, then that word can only be 6 letters in length before the next word kicks in with the X character. Miles doesn't fit this criteria, but inches does. We now have effectively inserted three words into our 32-Symbol code (shown below).

We know that only 5 inches from Mount Diablo lands in San Francisco, so it's now easy to insert the figure 5 before inches. We cannot insert the word "five" because "radians five radians" doesn't read fluently. Once we have added the figure 5 before inches, it's easy to add "and" into the sentence to read "radians and 5 inches". Whether the reversed letter F represented 5 is impossible to tell. The rest of the solution is now pretty easy to guess. We are left with Radians and 5 inches _ _ _ _ _ _ _ _ radians. Once a line is drawn radiating away from Mount Diablo at 4 radians and magnetic north, we then have to travel 5 inches along the 4th radian value. This gives us the final two words of the 32-Symbol code of "along the".

We now have the full answer of Radians and 5 inches along the radians. If this reasoning had been used between June 26th 1970 and July 26th 1970 and given to the police prior to the arrival of the Little List letter, the suggested solution to the 32-Symbol code would probably have been accepted when the Zodiac Killer wrote "PS. The Mt. Diablo Code concerns Radians and # inches along the radians" at the foot of the July 26th letter. Unfortunately it wasn't.

The Zodiac Killer used exactly the same concept in his 13-Symbol code by highlighting three 8's by circling them (representative of Jesus Christ, resurrection, infinity and a new beginning). These again were found to begin each element of the solution "Fk, I'm crackproof", which when inserted into the code was infinite and circular in nature. The first 8 began FK, the second 8 began IM, and the third 8 began CRACKPROOF. The letters K and M were already present in the code as an aid. Just like the 32-Symbol code, the Zodiac Killer gave us the answer to the 13-Symbol code on October 5th 1970, seemingly frustrated, or had become aware that his clues were too difficult and scarce in nature. In both the 13-Symbol and 32-Symbol codes, the Zodiac Killer created anchor points where each word was to begin. Once the month of October 1970 had rolled on by, the Zodiac Killer would never elaborate on the workings of his ciphers ever again.

The Mount Diablo Map and Code Solution    The Codes of Zodiac Never Required an External Solve

In a previous article entitled The Dick Tracy 340 Cipher we explored the idea that the "13 punch-holes" and "red crucifix decoder" of the October 5th 1970 communication, may have been giving us a clue into the "Paradice and Slaves" formation within the 340 cipher. While this may remain the case, there could be a more direct link between the 13-Hole postcard and the April 20th 1970 13-Symbol cipher (and a case of dual functionality). There is the obvious link of 13 characters in the April 20th 1970 code and the 13 punched holes, but there is also the common link of phraseology in "What is the price tag now" and "I am mildly cerous as to how much money you have on my head now". These were the only two times the Zodiac Killer asked about the bounty on his capture. There is also a link between both configurations. The 13-Symbol cipher had three circled number 8's positioned in the center of the code (with 4 characters either side and two between them). The 13-Hole postcard had three distinct punch-holes in the center of the formation (with 4 punch-holes either side and two between them).

When you look at the 13-Hole postcard it is clear that the Zodiac Killer had plenty of room to configure the punch-holes into any arrangement he liked, yet he chose to overload one line with ten holes, with just three on the other. One could be forgiven for believing there was purpose in this design. 

The April 20th 1970 and October 5th 1970 communications were littered with Christian symbolism. We have the Red Crucifix, the three 8's (which in Christian numerology represents Jesus, or Christ the Redeemer), the Celtic Cross and the Anchor (adopted by Christians as a symbol of hope in future existence). The number 8 (infinity) in Christianity is representative of eternal life, rebirth, regeneration or a new beginning. They all play into the belief of an afterlife. This brought forward the notion that the number 8 in the 13-Symbol cipher was the beginning of each element of the phrase "Fk, I'm crackproof" (as shown above in green). In the diagram above, one can see that the letter F becomes the 5th letter in both sequences, the letter I becomes the 7th letter in both sequences, and the letter C becomes the 9th letter in both sequences, with the K and M slotting in between. In short, the letters FIC in both instances are separated into three circles, positioned identically in both sequences. The use of circles in both the 13-Hole postcard and 13-Symbol cipher plays directly into the phrase "Fk I'm crackproof", which when placed around the already existing K and M in the code, forms an eternal and circular repeating sequence. The April 20th 1970 communication now satisfied the October 22nd 1969 challenge by cryptographer D.C.B. Marsh in the San Francisco Examiner, for the Zodiac Killer to reveal his name. The letter now read "This is the Zodiac speaking. By the way have you cracked the last cipher I sent you. My name is Fk, I'm crackproof".                

The 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 February 16th 1970, a militant group placed a bomb packed with fence staples on the window ledge of the San Francisco Police Department Park Station, killing Sergeant Brian McDonnell and severely injuring and wounding nine other police officers. The Zodiac Killer had nothing to do with the brazen attack, but spurred on from his previous threats upon random police targets, managed to reference the Park Station bombing, in accompaniment to the diagram of a school bus on the Southern Freeway. The Zodiac Killer stated in the April 20th 1970 letter, that  "Even though I talked about killing school children with one. it just wouldn't doo to move in on someone else's teritory.  But there is more glory in killing a cop than a cid because a cop can shoot back". This killer had targeted six kids like sitting ducks and blindsided his seventh victim, because he was a coward. The idea that this man would target somebody who could shoot back was extremely unlikely, with the threat to escalate his attacks, more a case of creating fear and panic in the community, rather than his willingness to do so.

It was likely the newspaper coverage of the Park Station bombing that inspired his following two communications. The Dragon card mailed 8 days later, carried the introduction of "If you dont want me to have this blast you must do two things. Tell everyone about the bus bomb with all the details. I would like to see some nice Zodiac buttons wandering about town. Everyone else has these buttons like, black power, melvin eats bluber, etc". The bombing at Park Station was believed early on to be the work of the Weather Underground or the Black Liberation Army, hence the Zodiac Killer's need to get some recognition by the requesting the wearing of Zodiac buttons and referencing Black Power. It may also be significant that he placed "I hope you enjoy yourselves when I have my Blast" right alongside a picture of Don Quixote and Sancho Panza, suggestive of a location. A statue of Miguel de Cervantes, Don Quixote and Sancho Panza can be found in Golden Gate Park in San Francisco, approximately one mile from Park Station (1899 Waller Street), which also sits in Golden Gate Park, in the southeast corner. This threat of a blast, in accompaniment to the imagery, indicative of a compassionless killer piggybacking upon the Park Station bombing, by suggesting a threat in the near vicinity. An ominous foreboding that was already embedded in the April 20th 1970 letter in the form of the school bus bomb diagram. Just two months later, on June 26th 1970, the Zodiac Killer would expand on his bus bomb diagram by supplying us with extra details. 

The Zodiac Killer had given us the drawing of his intended bomb location, complete with photoelectric cells, car battery and timer. But now was the time to "clue us in" on where it was buried (or where it was threatened to be buried). The location he had designated was just three miles south of the Park Station, right alongside Ingleside Police Station on the Southern Freeway. The Zodiac Killer's threat never materialized, but somebody else did move in on his promised territory, when on August 29th 1971, Sergeant John Young was shot and killed inside the Ingleside Police Station. Two men brazenly entered the reception area and thrust a 12-guage shotgun through an opening in the bullet proof glass, striking and killing Sergeant John Young and injuring a civilian employee.

A bomb placed on the embankment of the Southern Freeway (274 feet from Ingleside Police Station) is notable for another reason. The Zodiac Killer didn't state he would "annihilate a school bus" on June 26th 1970, he promised to "annihilate a full school bus", suggesting that the school bus would have to be near the terminus of its route. The Thomas More Catholic School had a bus route along the Southern Freeway, just yards from Ingleside Police Station, passing a location mimicking the bus bomb diagram (shown below in red), with the school itself situated in the southwest corner of San Francisco. Children traveling from all over San Francisco would have been seated on this bus as it drove south in the morning light. The sun would have been to the east, with the school bus exiting the freeway extremely close to the school. It most certainly would have been full as it passed the proposed bomb location.

The Zodiac Killer threatened to kill police and place bombs, but he will be ultimately remembered for targeting the young and defenceless - and just like most serial killers - be recognized for the coward he was.