On April 20th 1970 the Zodiac Killer mailed a letter to the San Francisco Chronicle with three key components. [1] The Zodiac Killer stated "I hope you do not think that I was the one who wiped out that blue meannie with a bomb at the cop station.  Even though I talked about killing school children with one. It just wouldn't doo to move in on someone else's teritory". The Zodiac Killer was referencing the murder of San Francisco police officer Brian McDonnell on February 16th 1970, who suffered devastating and sadly fatal injuries two months earlier, when a bomb packed with fence staples exploded on an outside ledge of Park Police Station in the Upper Haight neighborhood. He continued [2] "But there is more glory in killing a cop than a cid because a cop can shoot back". [3] The Bay Area murderer also included a bus bomb diagram, with a school bus traveling south in the morning and the sun rising to the east. The bomb was positioned on a steep embankment.

It therefore shouldn't be any surprise that his next letter on June 26th 1970 contained all three of these components in its design: [1] He claimed he had set a bomb by Ingleside Police Station, [2] claimed his "glory" by insinuating his involvement in the shooting death of Officer Richard Radetich and [3] his bus bomb diagram matched perfectly the bomb to be set by Ingleside Police Station. In addition, the history of Officer Richard Radetich is pertinent to the location of the bomb. 

In the June 26th 1970 Button letter he stated "The Map coupled with the code will tell you where the bomb is set*. It is clear the bomb was to be set in San Francisco, the target for the majority of his communications and ire toward police. The code provided the inches (5 to be exact) and the map was to provide the radians, to be set at Mag. N (magnetic north) from his zero point clockwise. This was plainly evident when he provided the extra two clues in the following Little List letter on July 26th 1970.

The first clue was the first set of crosshairs, where he placed the bold, black circle at 4 radians and magnetic north (246 degrees} around the circumference. The second clue was therefore the solution to the 32 symbol cipher containing the inches - where he placed the hashtag and arrow for the number 5 to be inserted. The bomb was to be set close to Ingleside Police Station, which to a high degree of accuracy fell extremely close to 4 radians and magnetic north, and five inches from Mount Diablo. The inches subtended from Mount Diablo at 246 degrees couldn't be more or less than 5, because a bomb (set at 4 or 6 inches) would have fell into the sea on the east and west side of San Francisco. The bold, black circle on the right, should be evident that the target was to be the San Francisco Police Department.

I have placed the number 5 into place, giving us the answer to the code of "Radians and 5 inches along the radians" (which is 32 letters in length). The positioning of the bomb had to meet certain criteria. With a high degree of accuracy, Ingleside Police Station was situated 4 radians and magnetic north, and 5 inches from Mount Diablo. However, the bus bomb diagram showed a school bus traveling from north to south in the morning, next to a steep embankment, with the sun rising to the east. This location is just 230 feet from Ingleside Police Station. School buses traveling from the northern and eastern edge of San Francisco to St.Thomas More Catholic School would travel the Southern Freeway, passing only 210 feet from Ingleside Police Station. From this location the bus would be traveling south in the morning to begin classes for the day, the sun would be rising from the east, and this location has a steep embankment mirroring exactly his bus bomb diagram of April 20th 1970. This portion of the Southern Freeway is flanked by the parking lot at the City College of San Francisco. This parking lot is the ideal location to access the embankment without parking on the freeway.      

Every criteria has now been met. The school bus, the route of the school bus on a freeway, the southerly direction, the steep embankment, the target of SFPD (San Francisco Police Department) and the 4 radians and magnetic north coupled with the code of 5 inches. A bomb set here would have had maximum impact, striking a school bus as Zodiac had promised, but more importantly, right under the noses of the San Francisco Police Department for acute embarrassment. However, there may be one other factor to contemplate, when we consider the reference to Officer Richard Radetich in the June 26th 1970 letter, containing the Mount Diablo code. The map and code took us to a location exactly bisecting Ingkleside Police Station and the City College of San Francisco.

Sgt Richard P. Radetich (25) was murdered on June 19th at 5:25 am, 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. Numerous magazine and newspaper articles covered his brutal execution and gave a background of the young officer's life. Officer Richard Radetich attended Balboa High School in San Francisco, before attending a criminology course at the City College of San Francisco with the express intention of joining the San Francisco Police Department. His first assignment was at Ingleside Police Station, before transferring to the Accident Investigation Bureau.  

The Zodiac Killer was an avid reader of the newspapers and had previously mentioned the murder of Officer Brian McDonnell on February 16th 1970, killed by a bomb placed on the ledge of Park Police Station. In the June 26th 1970 Button letter, the Zodiac Killer claimed his involvement in the murder of Richard Radetich, while giving us a location for the bomb that bisected Ingleside Police Station and the City College of San Francisco - two of the places Officer Richard Radetich attended prior to his murder, while serving in the Accident Investigation Bureau. Had the Zodiac Killer read about the murder of the young officer, and cynically positioned his claimed bomb on the Mount Diablo map at a location pertinent to Officer Radetich's life. Exactly between Ingleside Police Station and the City College of San Francisco? And the design of the bus bomb diagram was just a fortunate coincidence to this location.

The April 20th 1970 bus bomb diagram was penned two months before the murder of Officer Richard Radetich, so if this location was deliberately earmarked well in advance of his murder, it is unlikely the Zodiac Killer chose it because of the history of the young officer in the newspapers subsequent to June 19th 1970. But it wouldn't rule out the deliberate targeting of an officer connected in some fashion to Ingleside Police Station or an advance knowledge of their history, however implausible this may seem. Whatever the case, the primary focus of Ingleside Police Station and an attack on an officer, because "there is more glory in killing a cop" is a viable one. The location of a proposed bomb on the Southern Freeway by Ingleside Police Station, matches both the Mount Diablo map and code of 4 radians set to magnetic north, and 5 inches along the 4th radian. The location also matches perfectly the bus bomb diagram within the April 20th 1970 letter. These still stand, irrespective of any connection to Officer Richard Radetich, which may have no bearing whatsoever. 

The Codes Of Zodiac Never Required An External Solve.

The brutal stabbing and murder of Robert Michael Salem on April 15th 1970 is so much more compelling as a potential Zodiac crime compared to other outlier murders linked to the Bay Area killer. I will do a brief run through of what we know so far, before adding a little more to the equation. This additional information will include the Good Citizen letter mailed to Sergeant John Lynch on October 7th 1969, just four days before the murder of Paul Stine in Presidio Heights. 

The Melvin Belli letter mailed on December 20th 1969 appeared to invoke the Frances Brown murder scene on December 10th 1945 at her 3941 North Pine Grove apartment in Chicago. She had been stabbed multiple times, with the knife discovered protruding from her neck. Her killer (supposedly William Heirens} had left an ominous message written in red lipstick on the wall of her apartment stating "For heavens Sake catch me Before I kill more. I cannot control myself". The Zodiac Killer had written on the Melvin Belli letter "I will loose all controol of myself. Please help me. I can not remain in control for much longer". The message on the wall of Frances Brown's apartment was written above a table lamp. It was therefore uncanny that the Zodiac Killer's next correspondence arrived on April 20th 1970, on the same day that the San Francisco Chronicle published details regarding the murder of Robert Salem, in which the killer wrote a message on the wall in blood -. and Robert Salem was a lamp designer, having them displayed in museums and art fairs around the world. If the statement of "I hope you have fun trying to figgure out who I killed" on the April 20th 1970 letter wasn't Robert Salem, it is extremely fortunate timing off the back of the Melvin Belli letter four months previously.  

For a copycat killer to read into the wording contained within the Melvin Belli letter, authenticated as Zodiac correspondence, and place Zodiac on the wall of Robert Salem's 745 Stevenson Street, San Francisco apartment in similar fashion to the Frances Brown murder scene, would take a special form of insight. Unless of course, it was the Zodiac Killer who murdered the lamp designer. This drives to the heart of the question - of whether the Zodiac Killer had crossed paths with Robert Salem in the preceding months to his murder - and was specifically targeted by the Bay Area murderer. By murdering somebody of relative acclaim and scrawling his pseudonym on the wall, he could certainly expect front page coverage in the Chronicle. We have speculated that the Zodiac Killer had a penchant for the dramatic, with his references to The Mikado, his Lake Berrryessa costume and the style of his communications. He certainly appeared to have artistic leanings. If the Zodiac Killer had befriended Robert Salem, then it may have come through a mutual love of the arts, either through a museum, the theater or an arts and crafts fair. 

The San Francisco Chronicle article on April 20th 1970 stated that "Salem's designs have been exhibited in England, Japan and Russia under State Department cultural exchange programs. Until last year (1969) he had been the lighting designer for restoration of the historic Haslett Warehouse on Hyde Street". In fact, the address is given as 680 Beach Street at Hyde, Russian Hill, San Francisco. It is situated just 1.5 miles from where Paul Stine began his fateful journey on October 11th 1969. Here is the view of the Haslett Warehouse from 700 Beach Street, just across the intersection of Hyde Road.  

"During the 1960s, California was the site of many outdoor art fairs, which nurtured a culture of independent artists and craftspersons. At this time there was an effort to sell crafts on the sidewalks of the liberal Haight-Ashbury neighborhood of San Francisco. Artists and street performers who illegally set up in public areas were frequently harassed and arrested by the police. In the 700 block of Beach Street adjacent to Victorian Park and near Fisherman's Wharf, between 15 and 25 artists would set up their displays and use lookouts to alert them to the arrival of the police". Wikipedia. This certainly would have attracted the attention of somebody like Robert Salem, who was working at the Haslett Warehouse just yards away. Is it possible the Zodiac Killer crossed paths with Salem at an art and crafts fair such as this? I wouldn't normally attempt to use such a speculative link but for October 7th 1969 Good Citizen letter, possibly mailed to Sergeant John Lynch from the Zodiac Killer.

With immense gratitude to Rubislaw32,  this correspondence was mailed on October 7th 1969, just two months after the "concerned citizen" card and four days before the murder of Paul Stine in Presidio Heights on October 11th 1969. It has been dubbed the "good citizen" letter, postmarked San Mateo and signed ''A good citizen", with a footnote from Sergeant John Lynch. It stated that the writer has a strong feeling of ESP. While having these feelings, the writer writes with a pencil. 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''. This letter referenced Beach Street, where Robert Salem worked during the latter months of 1969. So we have four intersecting points of interest - an art and crafts fair on Beach Street, where artist Robert Salem likely worked during the mailing of the October 7th 1969 "Beach Street" letter, with Paul Stine picking up his killer just 1.5 miles south, only four days later. It may not be compelling, but the possibility exists that the Zodiac Killer crossed paths with the lamp designer before April 15th 1970 and murdered him at his 745 Stevenson Street apartment, all while inspired by the December 20th 1969 Melvin Belli letter some four months earlier.

This is another speculative article searching for the name of the Zodiac Killer within his communications - so caution must be applied to any conclusions that are reached in the following analysis.

After the challenge by Dr. Marsh on October 22nd 1969 requesting that the Zodiac Killer give us his real name in a cipher "however complicated", the notion of a killer hinting at his name in later communications is certainly plausible. Presented in a hidden format, the Zodiac Killer knew that it could never be used as evidence against him, unless the unearthed solution could be proven beyond doubt to be the correct one. In the article Return to Sender we explored the introduction and answer to the 13 symbol cipher of "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 Zodiac Killer effectively giving us his name, but in the shortened format. 

Three months later, the Zodiac Killer mailed the Little List letter on July 26th 1970 paraphrasing the recital of Groucho Marx's As some day it may happen from the Gilbert & Sullivan comedic opera, The Mikado. On October 12th 1970, the San Francisco Chronicle featured this letter under the title of Gilbert and Sullivan Clue to Zodiac, stating "A quiet search for onetime Ko-Ko's has turned up none that could be Zodiac. Obvious differences in physical description and handwriting comparisons have cleared all Ko-Ko's tracked down since the arrival of the July 27 letters". But what if the Zodiac Killer wasn't choosing the character of Ko-Ko because he played him in a production or even liked the theater, but the name Ko-Ko was somehow pertinent to his identity. Bearing in mind the phrase "My name is....Fk, I'm crackproof", could the Zodiac Killer's surname begin with Ko. The phrase "FK, I'm crackproof" is actually 14 letters long, but it was fashioned into a code of only 13 characters. Could this deliberate formatting indicate his initials were FK in a name comprising of 13 letters?

Although questionable Zodiac correspondence, the December 1990 Eureka card yet again featured Groucho Marx in imagery on the front of the card, promising us his name yet again. The card read "From your secret pal, can't guess who I am yet? Well, look inside and you'll find out" - and contained within was a xerox copy of two keys. This too triggered the notion of a surname beginning with K. The Exorcist letter mailed on January 29th 1974 also featured a verse recited by Groucho Marx, but more importantly, the verse of Tit-Willow by Ko-Ko was preceded by the line "Signed, yours truley", implying the character in the verse had something to do with his name. This wasn't all.

We argued that the Zodiac Killer gave us the answers to all his "unsolved" codes in his own words, and the Celebrity Cypher mailed on September 25th 1990 to the Vallejo Times-Herald may have followed a similar pattern. The name of the sender was hidden behind 5 and 8 characters totaling 13, placed on the address side of the postcard and at the foot of the communication. A Celebrity Cypher with a likely introduction of "My name is", exactly like 13 symbol cipher mailed on April 20th 1970. If the initials of the killer were given in that instance within the phrase "Fk, I'm crackproof", then there are reasonable grounds to believe the 5 and 8 letters of the name on the Celebrity Cypher begin with an F and K also. In the Return to Sender article we hypothesized the forename as "Frank", based upon the phrase "how much money you have on my head now" in reference to the stamp on the April 20th 1970 letter - and this fits nicely into the Celebrity Cypher solution. I have speculatively placed "Ko" at the beginning of the surname regarding The Mikado references, but will venture no further. There are possibilities based on the "keys" provided by the Eureka card to suggest his surname could end in "key" or "ki" such as "Kominski", however, there are plenty of other options pertaining to the xeroxed image.

Comparisons can be drawn between the April 20th 1970 and September 25th 1990 communications with respect to a name comprising of 13 letters (split into 5 and 8 characters) - and bearing in mind the Christmas card, likely mailed close to December 25th 1990 continuing the theme of promising us his name - can a link be forged between all three regarding the identity or name of the Zodiac Killer? 

The following will be extremely speculatory and should not to be taken too seriously, but I wanted to examine the prompt by Professor D.C.B. Marsh who told the 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 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 - however complicated - which will truly and honestly include his name".

When recently promoting the notion of a killer providing us with all the solutions to his ciphers in Three Months After the Mount Diablo Code, it was considered that the Zodiac Killer did respond to Dr. Marsh, but he certainly wasn't going to be as forthcoming as to provide us with his full name as Dr. Marsh had honestly requested. Hence the idea that he did give us his name, albeit in the abridged version of his initials which he supplied to us in the October 5th 1970 '13 Hole' Postcard. When this was slotted into the April 20th 1970 '13 Symbol' Cipher it read like so: "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 Zodiac Killer had in effect answered the request of Dr. Marsh, although in a rather devious manner. However, Dr. Marsh issued this challenge on October 22nd 1969 and the 340 Cipher came before the 13 Symbol Cipher.     

One of the most prominent features in the 340 Cipher is the sixth line where he corrects a forward facing K to a backwards facing K, similar in nature to the way he reversed the "Fk, I'm crackproof" phrase on the 13 Hole Postcard. The proximity of F and K can be noted in these two outstanding features - and possibly the Zodiac thought it mildly amusing to provide his name to Dr. Marsh in the extremely "complicated" manner of reversing his name or initials. Everybody was searching for a stunningly complicated solution to the 340 character cipher as Dr. Marsh had requested, so the Zodiac Killer gave us the complete opposite.

The connection between the 13 Hole Postcard and 13 Symbol Cipher was not only bound in the "Fk, I'm crackproof" solution, but the two phrases he used in each communication didn't go unnoticed either. The Zodiac Killer inextricably tied the two correspondences together using similar phraseology, such as "What is the price tag now" and "how much money you have on my head now". On January 29th 1970, the Yellow Cab Company put up a thousand dollar reward for any information leading to the arrest of the Zodiac Killer. In addition, the Teamsters Union which represents the Yellow Cab Company were reported in the San Francisco Chronicle to be considering offering a further reward on February 8th 1970 in the case of Paul Stine and Charles Jarman (another taxicab murder victim). This news was likely what prompted the Zodiac Killer to open this communication with the words "I am mildly cerous as to how much money you have on my head now".  Or could there be another more subtle clue in these phrases with regard to his name?

Where on the April 20th 1970 letter and throughout much of his communications to date (including the 340 Cipher) could money or a price tag be found on a head? The 13 Symbol Cipher letter carried a dated 1966 Franklin D. Roosevelt stamp, where indeed "money" or a "price tag" could be found 'on' the head of Franklin D. Roosevelt. Was this a subtle hint to his first name of "Franklin" or "Frank". This would satisfy the F part of "Fk, I'm crackproof" - but as stated earlier,  very speculative to say the least.

Another communication where he promised us his name was the October 27th 1970 'Halloween' Card, in which he gave us an odd-looking symbol and placed it on the left side of the envelope and the Halloween Card inner, followed by the letter Z. The correct way to address an envelope is to write the sender's name and address in the top left corner of the envelope, shown here on a Youtube video, and the recipient address (in this case Paul Avery) in the center of the envelope. Therefore, this strange symbol could equate to the sender's name. Since we are looking for the initials of the Zodiac Killer (which may be reversed for a third time), it is extremely promising that we have an F looking character on the right side yet again. I don't like too much manipulation and the use of mathematics anymore, but on this occasion I will choose the path of least resistance and take the 7 and 4 dots to equal 11 (K being the 11th letter of the alphabet) - and therefore give us a joined K and F for his name on the return section of the envelope. Unfortunately, manipulation such as this always leads to the possibility of multiple solutions, so we have to be guarded to any conclusions we make. Finally, I would like to take a look at the sister card to the Halloween Card mailed in the December of 1990. It too promised us his name.       

The greeting card was again from our Secret Pal just like the Halloween Card twenty years earlier - it began with the message "FROM YOUR SECRET PAL CAN'T GUESS WHO I AM YET? WELL, LOOK INSIDE AND YOU'LL FIND OUT". Then promised to keep us guessing on the card inner.

All the Zodiac Killer added to the card inner was a Xerox copy of some "keys". It really couldn't be any simpler. The card outer stated "From your secret pal, can't guess who I am yet? Well, look inside and you'll find out" followed by "keys". This may very well be the final really complicated answer to the challenge laid down by Dr. Marsh all those years earlier. The surname of Keys, Keyes or Keays would satisfy the K of FK, from the phrase "This is the Zodiac speaking. By the way have you cracked the last cipher I sent you? My name is Fk, I'm crackproof".

This mocking response to Professor D.C.B. Marsh, who requested that the Zodiac Killer "send The American Cryptogram Association a cipher code - however complicated - which will truly and honestly include his name" was probably befitting of the Zodiac Killer. The answer may have been simpler than we could ever of imagined. Return to sender: Franklin Keys (or alternate options above).

Of course, I am not claiming this to be the answer regarding the identity of the Zodiac Killer, but it would be rather appropriate for the Zodiac Killer to have begun his letter writing campaign with Franklin on the stamps of his July 31st 1969 trinity of communications, and ended with his surname of Keys in 1990 - and thumb a finger to all the cipher experts trying vainly to crack his extremely complicated ciphers, when the answer was literally staring us in the face all along. 

The Zodiac Killer gave us the answers to his six unsolved ciphers by March 13th 1971 without ambiguity, but effectively gave us all the answers by October 27th 1970. It is important to read Three Months After the Mount Diablo Code to understand all of the following, but I shall give a very brief recap. The Zodiac gave us the answer to the Mount Diablo code (32 symbol Cipher} in the Little List Letter on July 26th 1970. In fact, he gave us the answer word for word, in the form of Radians and 5 inches along the radians (all we had to do was add the number 5 where he placed the arrow and hashtag}. The 13 Hole Postcard on October 5th 1970 gave us the answer to the 13 Symbol Cipher word for word, in the form of Fk I'm crackproof. The Halloween Card on October 27th 1970 gave us the answer to the 340 Cipher word for word, in the form of Paradice and Slaves. No mathematics was required and no manipulation was needed - all we had to do, was use the three phrases that Zodiac provided us with in three consecutive communications, to answer the three previously unsolved ciphers. But that wasn't all. The Zodiac gave us the answer to both the Fairfield Letter codes of December 7th and 16th of 1969, again word for word using the Halloween Card. The 18 unsolved characters in the 408 cipher he again gave us the solution word for word, using the trinity of communications on July 31st 1969 and following letter on August 4th 1969, when he revealed his pseudonym to the world. However, there is even more.

The Zodiac Killer's 408 Cipher was effectively a written message that he enciphered into characters. When you take a look at the decoded message, it isn't structured and organized - because one line or row bleeds into the following. The Zodiac Killer didn't contain his words within the confines of one row. For example, when he opened the cipher with "I like killing people", the letter E is positioned at the beginning of the second row. This randomness is not displayed in the answers to his remaining six unsolved portions of code. The answer to the 18 unsolved characters, the 340 Cipher, the two Fairfield letters, the 13 Symbol Cipher and the 32 Symbol Cipher are all organized and deliberately structured, where every single solution and word is contained within each line - and does not leak from one row to another. Let us take a look at the 13 Symbol Cipher that exhibits symmetry within its design.             

I don't have to explain the above, because its structure and symmetry is there for all to see. The Zodiac Killer had already responded to prompts by Vallejo Police Chief Jack Stiltz to send more details to prove the letter writer and killer were one and the same. The more the Zodiac Killer wrote, not only lessened his time for killing, but may have provided additional clues to detectives regarding his identity. This tactic was likely adopted by Professor D.C.B. Marsh in the October 22nd 1969 San Francisco Examiner newspaper article by Will Stevens, which laid down a challenge to the Zodiac Killer to reveal 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 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 - however complicated - which will truly and honestly include his name".

The above invitation by Dr. Marsh, quoting Edgar Allen Poe, was met with the 13 Symbol Cipher that mirrored a code used in Poe's A Few Words on Secret Writing. The alphabet being split A to M, and N to Z. The 13 Symbol Cipher began with A and ended with M. So it was logical to place the alphabet alongside the 13 Symbol Cipher and see if any patterns emerged by counting the numerical difference between corresponding characters. This resulted.

I don't want to labor the point again, so for a full explanation please visit the article Embedded Symmetry  Suffice to say, that when the Zodiac's solution or answer to the 13 Symbol Cipher was inserted into the code above, it showed an organized and structured pattern without a word bleeding from one end of the cipher to the other. The Zodiac Killer gave us the cyclical solution of Fk I'm crackproof on October 5th 1970, and followed this up with the line "This is the Zodiac speaking Like I have allways said, I am crack proof" on March 13th 1971. But in the Los Angeles Letter you will notice he separates "crackproof" to "crack proof", exactly how it is found in the 13 Symbol Cipher. It does not bleed from the end of the cipher to the start.

The first 8 begins FK. The second 8 begins IM. The third 8 begins CRACKPROOF. But CRACK and PROOF are separated, without either word being fragmented. The FK and IM also fit nicely around the existing K and M in the cipher. The cipher solution maintains an organized and symmetrical appearance. The introduction on the April 20th 1970 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". He was leading us into the belief these were his initials.

The Paradice and Slaves configuration from the Halloween Card to the 340 Cipher also exhibited form, with Paradice exactly bisecting the columns of the 340 Cipher, and Slaves exactly bisecting the rows of the 340 Cipher in a 17 X 17 pattern. Each word contained within a row or column. The Halloween Card envelope providing us with "sorry no cipher" in a cross formation, not only telling us that the 340 wasn't a standard cipher, but the design of the 340 was to be found in a cross formation.

The 32 Symbol Cipher also adhered to a solution where no word bled from one row to another. The 32 Symbol Cipher contained two rows of 17 and 15 characters - obviously created this way for a purpose. When we discovered that the number 5 was to be inserted into the cipher using the arrow and hashtag, the answer of Radians and 5 inches along the radians again fell perfectly into the 32 Symbol Cipher with no word extending from one line to another. You will notice that when the Zodiac Killer provided us with the answer in the July 26th 1970 Little List Letter, he self-contained the answer on a separate line, with the first Radians beginning with a capital letter. This was the beginning of the code solution.

"PS. The Mt. Diablo Code concerns Radians and # inches along the radians" was in fact Radians and 5 inches along the radians. When this is placed into the 32 Symbol Cipher, you will notice that once again it retains separation, with "inches" ending line one, and "along" beginning line two. Each word is contained within the line. This organization and structure flies in the face of the solved portion of the 408 Cipher and implies a deliberate and calculated design. But we need to take it even further.

Explained in greater detail in the article The Answer to the Z38 Code, the structure of the Zodiac 38 character cipher was pointed out. The code below has been structured with different character counts on each line (unlike the 408 and 340 ciphers), but is instead arranged in a formation of 12 characters on line one, 7 characters on line two, 5 characters on line three, 6 characters on line four and 8 characters on line five. This may suggest that the words are contained separately on each line, without running from one line to another. We would expect Slaves and Paradice to be grouped together - and the last two lines satisfy this character count of 6 and 8. We then have three lines remaining of 12, 7 and 5 characters. By Gun satisfies the 5 characters, By Knife satisfies the 7 characters, and By Fire, By Rope satisfies the 12 characters. This forms the basis of the completed 38 character code solution, mimicking the second Fairfield Letter design and the exact wording on the Halloween Card configuration. Furthermore, no word extends from one line to another, exactly as displayed in the above codes.

So far (including the Tim Holt comic book unearthed by Tahoe27), every single solution or answer to the ciphers can be achieved using the exact words employed by Zodiac from three consecutive communications spanning July 26th 1970 to October 27th 1970. [1] Radians and 5 inches along the radians [2] Fk I'm crackproof [3] Paradise and Slaves, and [4] By Fire, By Gun, By Rope, By Knife, Paradice and Slaves. And none extend or bleed into another line, or from end to beginning in the 13 Symbol Cipher. That is five ciphers down with one to go. 

The Zodiac Killer claimed that his 408 Cipher contained his identity or pseudonym. What was important to the Bay Area murderer was the structure exhibited by all the above codes. The characters he used were of no particular significance, because they weren't designed to be solved without future Zodiac input. This input came towards the end of his letter writing campaign, when he supplied us all the answers in just three consecutive communications. He was effectively wrapping up business. There was no way a man with such an inflated ego and inability to resist writing to the newspapers, could keep the secret to his ciphers for upwards of five decades. The answer to the 408 Cipher was given to us in just four days, contained in the trinity of July 31st 1969 letters and the August 4th 1969 'Debut of Zodiac' Letter. He claimed his identity was in the 408 cipher - and we know his identity was "Zodiac" because he gave us his pseudonym. All we then had to do, was fit Zodiac around the declaration of who he was. 

Initially, the Zodiac Killer had intended to leave 12 characters at the base of the 408 Cipher, but his accidental omission of the word "people" when he encoded his message, inadvertently left him with 18 unsolved characters. However, this was of no consequence - it was an easy adjustment. You will notice again, that the unsolved 18 characters are split into an ungainly 1 and 17 configuration. If we are to hold true to single words not bleeding from one line to another, then the single character must stand for I or A. We know that the Zodiac Killer was an egotist, beginning the 408 Cipher with "I like killing people because it is so much fun". He also began two of the July 31st letters with "I am the killer". So it wouldn't be any great leap of faith to believe that the isolated singular character on line 23 was "I". Coupling the "Zodiac" with "I am the killer" to produce "I am the Zodiac Killer" satisfies his declaration of identity and the 18 characters at the base of the 408 Cipher. We again have used only the words written by the Zodiac Killer - and no word extends from one line to another. The third of code containing his identity was mailed to the San Francisco Chronicle, which is why he began that introduction with "This is the murderer". He was reserving "I am the Zodiac Killer" for the base of the 408 Cipher.  

We now have six unsolved portions of code answered, using only the words written by the Zodiac Killer in a total of four communications. Every single answer was organized and structured to remain within each row, line and column with no manipulation whatsoever. We can wait another 50 years for these codes to be "solved" - or believe they were all answered by October 27th 1970 from the pen of the Zodiac Killer.

The following article will coalesce several pieces of work from 2019 into one cogent story regarding a handful of communications mailed by the Zodiac Killer in 1970. For some, the following will be repetitive, for which I apologize. It will hopefully make the case that the Zodiac Killer was winding down his operations and ultimately revealing the answers to his Z340, Z32 and Z13 ciphers and codes, to which he knew were practically unsolvable without such a prompt. The Zodiac Killer was a narcissistic braggart, who boasted of his exploits and threatened all and sundry with the possibility of more murders and mayhem if his demands were not met, including the claim he had killed far more than could be accounted for. If we applied the same model to his ciphers and codes, we would have expected him to be unable to resist giving us the answers - or at the very least - some clues to break open his puzzles. The notion of a killer keeping deathly silent on the solutions to his codes for up to 50 years, runs contrary to everything we know about the Bay Area murderer during his brief but deadly reign. That is why I don't believe he did.

The story begins with the final thing he wrote on the July 26th 1970 Little List Letter, and finishes just two communications later with the October 27th 1970 Halloween Card. All the answers to his codes were contained in just three short months. The end of the Little List Letter read "PS. The Mt. Diablo Code concerns Radians and # inches along the radians". The Z32 was the easiest code to crack because the Zodiac Killer just gave us the answer above - the code concerned "Radians and inches along the radians". Why make it any more complicated than it has to be? A code of 29 unique symbols within a total of 32 characters is simply not solvable without a key - and there is insufficient wording on the 13 Hole Postcard, Halloween Card or Los Angeles Letter written in plain English to formulate any such key. The Z32 is even worse than giving us the English alphabet of 26 letters, replacing M with A, W with B and H with C and saying "now solve it". There is no transposition key present in the remaining three communications from October 5th 1970 to March 13th 1971, so if the Zodiac Killer was to be consistent in his inability to resist revealing his deeds, then the only realistic alternative is he gave us all the answers instead.

Not only did the Zodiac Killer give us the answer to the 32 character code on a separate line, he capitalized the first "Radians" to effectively tell us this was the beginning of the solution (he didn't capitalize the second "radians", so why the first). You need look no further than the Paul Stine police report to notice that the hashtag symbol is used in conjunction with a number. The Zodiac Killer by use of an arrow pointer underneath the hashtag, was telling us to replace the hashtag with a number value. The Mount Diablo map scale was 6.4 miles to the inch, so it is probably unsurprising that the "Mt Diablo code would concern inches". In this instance, I have placed the number 5 into place, giving us the answer to the code of "Radians and 5 inches along the radians" (which is 32 letters in length). The reason for 5 inches is self explanatory, because 4 or 6 inches from Mount Diablo to San Francisco would fall into the sea on the east and west side. The San Francisco element will be covered shortly. The Zodiac Killer also gave us a second set of crosshairs (shown below).

This was the first time the Zodiac Killer had ever placed an accentuated zero within his crosshairs alongside the acronym SFPD. This had to be the second clue to the location of the bomb. The hashtag and arrow signified the value of inches required, so this had to signify the radian value. By some massive stroke of luck (almost beyond belief), the bold, black accentuated circle fell over 246 degrees on a compass rose - which is 4 radians and magnetic north (17 degrees in 1970). Therefore, the target of his bomb must have been 4 radians and magnetic north, and 5 inches along the radians. 

All Zodiac's bomb threats were focused towards the San Francisco Chronicle and San Francisco Police Department, so placing this bomb location alongside the acronym SFPD should tell us that the threat was most likely focused toward a police station. By another massive stroke of luck, when we travel 4 radians and 5 inches from Mount Diablo, the target area for the bomb lies right by Ingleside Police Station. Allowing for a degree of flexibility of less than 1%, by the Zodiac Killer rounding off his radians and inches, along with the black circle diameter, no other San Francisco police station comes close. However, we need to find a location where a school bus would be traveling from north to south (with the sun to the east), that has an embankment on the right side (as displayed on the April 20th 1970 bomb diagram), with easy and covert access to that embankment, and within a few hundred feet from Ingleside Police Station. The Zodiac Killer certainly wouldn't have wanted to attract attention by parking on the road itself, but by accessing the incline from a secondary location - likely at the top of the embankment - he could achieve this task in relative anonymity. Fortunately for us, that location sits only 230 feet from Ingleside Police Station. The perfect location for the Zodiac Killer to target a school bus and thumb his nose at the San Francisco Police Department, with covert access to the top of the embankment via the car park of San Francisco City College.             

Then came the 13 Hole Postcard punched in the style of a 'Dick Tracy' code with a "red crucifix decoder". What are the chances that if we arranged the 13 holes into the shape of a cross and place it over the midsection of the 340 cipher both horizontally and vertically, it would reveal the wording "paradice" and "slaves"? Then, what are the chances that the Zodiac Killer would write "paradice" and "slaves" in his next communication in a cross formation on the card, accompanied by "sorry no cipher" in a cross formation on the inside of the Halloween Card envelope? - totaling three cross formations - but supposedly, all created for absolutely no reason whatsoever in just two communications. Isn't it more believable they were created for purpose. The Zodiac Killer could easily have written "sorry no cipher" just the once, but deliberately fashioned it this way to tell us that the 340 character cipher was not a cipher after all. It was simply a design of "paradice" and "slaves" as exhibited by the Halloween Card. Throw in a few bigrams, pivots and 'corrected sixth line', and hopefully it will look convincing. 

All these clues from the back end of the Little List Letter to the Halloween Card giving us the literal answer to both the Z340 and Z32 in "paradice" and "slaves", and "Radians and 5 inches along the radians". Could either the 13 Hole Postcard or Halloween Card give us the answer to the Z13 as well? Again, totally unsolvable because of its limited number of characters, the Zodiac Killer could either keep quiet for up to fifty years or give us the answer.

From a previous article: On January 29th 1970, the Yellow Cab Company put up a thousand dollar reward for any information leading to the arrest of the Zodiac Killer. In addition, the Teamsters Union which represents the Yellow Cab Company were reported in the San Francisco Chronicle to be considering offering a further reward on February 8th 1970 in the case of Paul Stine and Charles Jarman (another taxicab murder victim). The April 20th 1970 letter gave us the code and was immediately followed by "I am mildly cerous as to how much money you have on my head now". The October 5th 1970 postcard gave us the possible solution of "Fk, I'm crackproof" and was immediately followed by "What is the price tag now". These are the only two communications in which the Zodiac Killer asked the police the price of his capture. These two communications not only had a code and an answer that fitted the code, but both were followed by the exact same question. When the Zodiac Killer was designing his 13 Hole Postcard, it is very likely he had at his disposal a copy of his original April 20th 1970 letter, or the San Francisco Chronicle newspaper cutting below, to which he was now supplying the answer. This may have been the trigger that influenced him to repeat the phrase "how much money you have on my head now" into the very similar "What is the price tag now". The Zodiac Killer, in essence, had inadvertently bound both communications together through phraseology, as well as code and solution.   

The Zodiac Killer introduction would now give us his name (albeit his initials) in absence of his full name. It would also read fluently as a sentence, as follows: "This is the Zodiac speaking. By the way have you cracked the last cipher I sent you? My name is Fk, I'm crackproof". Nobody realistically believed he was going to supply his full name, but this way he satisfies the promise in a restricted format. Two communications mailed nearly six months apart, with a solution that satisfies the code, as well as a satisfactory introduction to the code - and both followed by the same question.    

The three 8's (representing Jesus Christ in gematria), along with the number 8 which symbolizes a new beginning, actually begins each element of the phrase Fk I'm crackproof. In addition, when we begin the phrase on the first 8, it fits perfectly around the existing K and M already present in the code and thereby creating a cyclical format, where the code ends and begins with the same letter. The Little List Letter provided the solution to the Button Letter and Mount Diablo code that preceded it. His next communication, the 13 Hole Postcard, provided the solution to the 13 Symbol Cipher before that, and finally the Halloween Card provided the solution to the 340 cipher. Three chronological solves to the three previous ciphers - and the only thing we had to add was the number "5", for which he inserted the hashtag and arrow. Why look for convoluted and excessively complicated solutions to these ciphers, when the Zodiac Killer gave us all the answers literally word for word.

This isn't a case of dragging wording from the entire Zodiac collection of cards and letters, but using just the two crosshairs of the Little List Letter, followed by the 13 Hole Postcard and Halloween Card. The bold, black circle and "PS. The Mt. Diablo Code concerns Radians and # inches along the radians" to answer the Z32. The 13 holes, red cross, "paradice" and "slaves", and "sorry no cipher" to answer the Z340. And finally, "Fk, I'm crackproof" to give us a shorthanded version of his name, while still retaining his anonymity. The alternative is that the codes are genuine, the designs on the 13 Hole Postcard and Halloween Card are devoid of any purposeful meaning, and the big-headed, braggart called Zodiac, kept his lips 'butoned' for however many years afterwards.  

FOLLOW UP ARTICLE:
THE ANSWER, ORGANIZATION AND STRUCTURE OF THE SIX UNSOLVED CODES

The 13 Symbol Cipher is simply too short for any meaningful decryption without a key or the answer. It is certainly possible to arrive at the correct solution using a key provided by Zodiac, but then you have to prove that the key you have found is the correct one, and your implemented methodology is plausible. The best way to find the solution to the Z13, as it was for the 32 Symbol Cipher, is to do absolutely no work whatsoever and just let the Zodiac Killer give us the exact answer. On this occasion, the Zodiac Killer designed the code and waited nearly six months to supply us with a verbatim solution.

The first thing to examine in the 13 Symbol Cipher is the circled triple 8 configuration. This is the feature that stands out in the code the most and where one would envisage the answer residing. Identify the meaning of the three eights and in what context they were chosen, and half the battle may be won. We can add the numbers up to create birth years and ages, but without instruction to do so, it could be argued that the idea rests in our head and not the Zodiac's. Therefore, we shall take the number 888 as one complete entity.

In Christian numerology, the number 888 represents Jesus, or sometimes more specifically Christ the Redeemer. This representation may be justified either through gematria, by counting the letter values of the Greek transliteration of Jesus' name, or as an opposing value to 666, the number of the beast. Wikipedia. This could indicate a Christian element to the code, especially when we consider the Zodiac's Celtic Cross, a form of Christian cross featuring a nimbus or ring that emerged in Ireland and Britain in the Early Middle Ages. The shape, usually decorated with interlace and other motifs from Insular art, became popular for funerary monuments and other uses. Then we have the tenth character in the code, likened to an upside down Aries symbol. However, when we consider the above and the Zodiac Killer's musings of an afterlife, another possibility emerges. Christians adopted the anchor as a symbol of hope in future existence because the anchor was regarded in ancient times as a symbol of safety. For Christians, Christ is the unfailing hope of all who believe in him: Saint Peter, Saint Paul, and several of the early Church Fathers speak in this sense. The Epistle to the Hebrews 6:19-20 for the first time connects the idea of hope with the symbol of the anchor. Wikipedia. This effectively ties five of Zodiac's characters under the Christian banner and the premise of an afterlife.   

On January 29th 1970, the Yellow Cab Company put up a thousand dollar reward for any information leading to the arrest of the Zodiac Killer. In addition, the Teamsters Union which represents the Yellow Cab Company were reported in the San Francisco Chronicle to be considering offering a further reward on February 8th 1970 in the case of Paul Stine and Charles Jarman (another taxicab murder victim). The April 20th 1970 letter gave us the code and was immediately followed by "I am mildly cerous as to how much money you have on my head now". The October 5th 1970 postcard gave us the possible solution of "Fk, I'm crackproof" and was immediately followed by "What is the price tag now". These are the only two communications in which the Zodiac Killer asked the police the price of his capture. These two communications not only had a code and an answer that fitted the code, but both were followed by the exact same question. When the Zodiac Killer was designing his 13 Hole Postcard, it is very likely he had at his disposal a copy of his original April 20th 1970 letter, or the San Francisco Chronicle newspaper cutting below, to which he was now supplying the answer. This may have been the trigger that influenced him to repeat the phrase "how much money you have on my head now" into the very similar "What is the price tag now". The Zodiac Killer, in essence, had inadvertently bound both communications together through phraseology, as well as code and solution.   

The Zodiac Killer introduction would now give us his name (albeit his initials) in absence of his full name. It would also read fluently as a sentence, as follows: "This is the Zodiac speaking. By the way have you cracked the last cipher I sent you? My name is Fk, I'm crackproof". Nobody realistically believed he was going to supply his full name, but this way he satisfies the promise in a restricted format. Two communications mailed nearly six months apart, with a solution that satisfies the code, as well as a satisfactory introduction to the code - and both followed by the same question.  

THE ANSWER TO THE 32 SYMBOL CODE - STRAIGHT FROM THE HORSE'S MOUTH

In the final instalment of this series we will attempt to refine the previous conclusions gleaned from the Zodiac Killer letters.
The Zodiac Killer stated on April 20th 1970 "I hope you do not think that I was the one who wiped out that blue meannie with a bomb at the cop station. 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.  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." In the correspondence, the Zodiac Killer was referring to the murder of San Francisco police officer Brian McDonnell on February 16th 1970, who suffered devastating and sadly fatal injuries two months earlier, when a bomb packed with fence staples exploded on an outside ledge of Park Police Station in the Upper Haight neighborhood. The wording in the letter suggested that the Upper Haight neighborhood was not somewhere he was prepared to venture, but the suggestion of a school bus bomb and police station, when we take into account the SFPD positioned strategically by the bold, black circle on the Little List crosshairs and indicative of a location point, brings forth the notion of a school bus bomb under the noses of the San Francisco Police Department. Targeting a school bus within sight of a police station would certainly have dealt law enforcement a mighty blow.

The Zodiac Killer may have had a location in mind, despite the fact it was never followed through on - and this location has tentatively been identified as four radians (+magnetic north) and five inches along the radian in two previous articles. The exact position he had in mind to set up his photoelectric cells to detonate the bomb didn't necessarily have to conform to these measurements exactly, just be close enough to be rounded off by the Zodiac Killer. However, the other clues he gave us in the April 20th 1970 and July 26th 1970 communications were replete with information. We narrowed down a section on Google Maps between Daly City and Ingleside in San Francisco (between 246 and 249 degrees).

To narrow down the location even futher, we should be looking for a bus route approaching a school from north to south (so the sun is rising from the east on the left side). The roadway must have sufficient embankment on its right side to elevate photoelectic switch B. It must be within the parameters of 4 radians and 5 inches (allowing for a small margin of error). The addition of the pronounced black circle within the crosshairs of the Little List Letter in the form of SFPD=0, is suggestive of a location close to a San Francisco Police Department. In other words, the Zodiac Killer may have intended his "blast" right under the noses of law enforcement: "Hey pig doesnt it rile you up to have your noze rubed in your booboos?" Despite not knowing the exact topography of this location in 1970, I have found a site just 230 feet from Ingleside Police Station alongside Southern Freeway. 

In a previous article we concluded that the 32 character code mailed to the San Francisco Chronicle on June 26th 1970 stated "P.S. The Mt. Diablo code concerns 4 Radians and 5 inches along the radian", based upon the clues the Zodiac Killer gave us in the Little List Letter on July 26th 1970. This led to an area somewhere between Ingleside and Daly City on the south edge of San Francisco. The Zodiac drew us a bus bomb diagram on April 20th 1970, suggesting he was going to place two photoelectric switches on an embankment or hillside on the right side of the road. He stated it was to be set up early in the morning when the sun was rising in the east. The images below show the El Camino Real by Outer Mission, heading south, with the April 20th 1970 'Bus Bomb' diagram superimposed over it. The hillside to the right is the type required to place his two photoelectric switches - one by the roadside and the other higher on the banking. Any school bus heading along this road for early morning assembly, would have the sun rising in the east (shining left to right in the image below).

If the Zodiac Killer had any intentions of blowing up a school bus (which is unlikely), then he would be targeting the schoolchildren on their way to school in the morning. If the children were being bussed in from other parts of San Francisco for this particular school (St. Thomas More Catholic School), then traveling from the north and east, the bus driver could be using Highway 101 and Interstate 280 in the direction shown by the red line below (recommended on Google maps). The blue circle is 4 radians (+ magnetic north), and 5 inches from Mount Diablo, satisfying the 32 character cipher and Zodiac's statement of "P.S. The Mt. Diablo code concerns Radians + # inches along the radians". The highway under the blue circle is traveling south with the sun to the east in the morning - and is heading toward St. Thomas More Catholic School (just 1.37 miles away).      

The Zodiac Killer stated on April 20th 1970 "I am mildly cerous as to how much money you have on my head now.  I hope you do not think that I was the one who wiped out that blue meannie with a bomb at the cop station.  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.  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. The new bomb is set up like this. Sun light in early morning. A + B are photoelectric swiches when sun beam is broken A closes circut. B opens circut, which makes B the cloudy day disconect so the bomb won't go off by accid. PS I hope you have fun trying to figgure out who I killed".

​​The choice of words the Zodiac used at the beginning of this communication were unfortunate, had his target been children from St. Thomas More Catholic School. The school was named after Thomas More, an English lawyer, social philosopher, author, statesman, and noted Renaissance humanist. He was also a Chancellor to Henry VIII, and Lord High Chancellor of England from October 1529 to 16 May 1532. He was sentenced under the Treasons Act 1534 and decapitated with an axe. Therefore, it was very unfortunate that the Zodiac Killer should state "I am mildly cerous as to how much money you have on my head now".

There are several other schools in this area between Ingleside and Daly City, but we must remember that it is the bus he was targeting, not the school. Therefore, we should prioritize the roadways in this area (shown by the red rectangle), from the perspective of a bus traveling south, with its left side facing east.

Unable to solve the 340 cipher and crack the message (in which I'm not alone), my only recourse is to try and prove that the 50-year-old cryptogram is unsolvable. I cannot do this on my own, so I need the Zodiac Killer to give me a hand and show me that it's not a valid cipher in his own words. The Zodiac Killer only gave us two visible 'crucifixes or crosses' (without the circle) in the cards and letters, throughout his entire correspondence with the newspapers. We can assume he did this for absolutely no reason whatsoever, or these two 'crucifixes or crosses' had a purpose. The two crosses were present in two consecutive cards - the '13 Hole' Postcard on October 5th 1970 and the Halloween Card on October 27th 1970. Both these cards also contained a hint that something was unsolvable. The '13 Hole' Postcard contained the phrase "Fk I'm crackproof", while the Zodiac Killer fashioned "sorry no cipher" in a cross formation on the envelope inner of the Halloween Card. If these statements are relevant to his ciphers, then we need to marry up the design of each card to his codes. Before we start, it must be noted that PARADICE and SLAVES in the cross formation is made up of 13 letters (the A pivotal to both words), but individually both words contain 14 letters - the total highlighted on each card. 

In the image below with respect to the '13 Hole' Postcard, you will notice that the Zodiac Killer has carefully positioned the cross beneath the number 13 - and we know Paradice and Slaves contains 13 letters in the cross formation. This is placed approximately in the center of the postcard with text either side. The 13 characters identified on the 340 cipher as Paradice and Slaves exactly mirroring this formation. Below the number 13 and cross on the postcard is the pseudonym Zodiac, accompanied by his crosshairs, almost mirroring the 340 cipher formation. The most notable feature on the 340 cipher is the corrected sixth line involving the letters F and K. Highlighted with a blue rectangle on the '13 Hole' Postcard we have "Fk I'm crackproof" written upside down. All we have to do now, is rotate the '13 Hole' Postcard 180 degrees clockwise to correct this text, so it can be read in the standard way. The corrected "Fk I'm crackproof" would now be present in the top right quadrant, just like the correctred FK in the 340 cipher.        

The Halloween Card also has the cross formation of Paradice and Slaves. This not only mirrors the "sorry no cipher" formation he provided on the envelope inner, but mirrors the 340 cipher formation also. In essence, the Zodiac Killer is telling us by extension that the 340 cryptogram is no cipher. Two consecutive communications, probably close to the anniversary he created the 340 cipher, and both designed to reveal the hidden crucifix or cross within the 340 cipher. Throw in the four By's in each quadrant and the pseudonym Zodiac from the '13 Hole' Postcard, along with "Fk I'm crackproof" and "sorry no cipher", and we have the Zodiac in his own words admitting the 340 character cryptogram has no solution. On the other hand, the Zodiac Killer is widely believed to be a liar - so maybe there's a message after all.

But just in case, let us stick "Fk I'm crackproof" into his third cipher and see if that's unsolvable as well.        

The Zodiac Killer again uses 13 characters/letters in his design, with the feature of three circled 8's. The circle and number 8 can be used to represent infinity or something of a cyclic nature. The cipher came with the handily placed K and M in the center of the code. All we have to do is place "Fk I'm crackproof" into place using these two letters (shown in blue), and in an unusual stroke of luck, the phrase is cyclic in nature. In addition, the three 8's (shown in green) just happen to begin each element of the phrase "Fk I'm crackproof" (Fk, I'm and crackproof). The Zodiac Killer may have twice told us his ciphers were unsolvable in the '13 Hole' Postcard and Halloween Card, but here he simply wouldn't shut up.

"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 previous articles we have discussed the Zodiac shift from gun to knife at Lake Berryessa, his claim to be responsible for the San Jose knife slayings on August 3rd 1969, the "Bleeding Knife of Zodiac" correspondence and the possibility he was referring to the Reet Jurvetson murder as victim number eight. Then came the Melvin Belli letter on December 20th 1969, the tone of which bore similarities to the Frances Brown murder scene on December 10th 1945 at her 3941 North Pine Grove apartment in Chicago. She had been stabbed multiple times and the knife was discovered protruding from her neck. Her killer had left an ominous message written in red lipstick on the wall of her apartment stating "For heavens Sake catch me Before I kill more. I cannot control myself". The Zodiac Killer had written "I will loose all controol of myself. Please help me. I can not remain in control for much longer". We know that the Zodiac Killer had a propensity for plagiarism, often using lines from The Mikado, along with his reference to The Most Dangerous Game - both of which dated back to 1885 and 1924 respectively. Therefore, it shouldn't be too much of a surprise that he would again bring up another knife murder, this time from 24 years prior. The question is, whether anybody in the four subsequent months to December 20th 1969 could reasonably have been expected to make the connection between the Melvin Belli letter wording and the murder of Frances Brown in 1945, other than its designer?

William Heirens was convicted in the murders of Frances Brown, Josephine Ross and 6-year-old Suzanne Degnan, who was savagely killed and dismembered. This is what makes the murder of Robert Michael Salem on April 15th 1970 so very interesting. He was brutally stabbed in his 745 Stevenson Street, San Francisco apartment, with the newspapers reporting that "the killer had apparently tried to decapitate his victim and when that failed, cut off Salem's left ear". Suzanne Degnan's killer had severed her head, which was ultimately found in a sewer one block from her residence. The murderer of Robert Salem had also written on the wall of the apartment above his body, this time with "red blood" as opposed to "red lipstick", but accompanied by the wording "satan saves" and "Zodiac". The writing was adorned with the drawing of an Ankh - it was commonly held in the hands of deities, or being given by them to the pharaoh, to represent their power to sustain life and to revive human souls in the afterlife.

This crime scene coming just under 4 months after the Melvin Belli letter, which didn't overtly mention the Frances Brown crime scene, but disguised it within the context of the wording chosen. The murder of Robert Salem at 745 Stevenson Street just 1.6 miles from the 1228 Montgomery Street residence of prominent attorney Melvin Belli, 821 meters from the Chronicle offices and 0.8 miles from Union Square (the pick up point of Paul Stine's fateful taxicab journey). Could a random killer have engineered such a crome scene at 745 Stevenson Street by reading into the disguised writings of the Zodiac Killer 4 months earlier, when it is most likely not many had made the connection to the Frances Brown murder scene over two decades earlier? Or is it more likely that the Zodiac Killer murdered Robert Salem with multiple knife wounds (just 1.6 miles from the Belli residence), scrawled "Zodiac" on the wall in "red writing" and attempted to decapitate his victim in similar fashion to that of Suzanne Degnan?

An article describing the murder of Robert Salem featured in the San Francisco Chronicle on April 20th 1970, just hours before the Zodiac Killer mailed his '13 Symbol' cipher to the newspaper, stating "I hope you have fun trying to figgure out who I killed"​​​. After four months of silence, one could easily come to the conclusion that this was no coincidence, especially when we draw a parallel from the "satan saves" message on the wall in blood, to the 888 circled in the '13 Symbol' cipher. This figure representing Jesus or Christ the Redeemer in Christian numerology. Throw in the "Ankh" and "afterlife", and the picture becomes clearer. The massive parallels of the Robert Salem murder to the Frances Brown murder are clear to see - but could a killer pretending to be Zodiac have worked all this out from the innocuous pleas for help in the Melvin Belli letter months earlier? The Zodiac Killer (referring to the murder of San Francisco police officer Brian McDonnell) stated that "I hope you do not think that I was the one who wiped out that blue meannie with a bomb at the cop station. It just wouldn't doo to move in on someone else's teritory". But was 745 Stevenson Street, just 1.6 miles from the Melvin Belli residence and 0.8 miles from Union Square, more likely the territory he operated within - and did so on April 15th 1970?   

The first coverage of the Salem murder was in the morning edition of the San Francisco Chronicle on April 20th 1970, so did the Zodiac Killer have time to construct a letter that included a cipher, bus bomb diagram and a reference to the murder of San Francisco police officer Brian McDonnell on February 16th 1970, who suffered devastating and sadly fatal injuries two months earlier, when a bomb packed with fence staples exploded on an outside ledge of Park Police Station in the Upper Haight neighborhood? The Zodiac Killer would had to have rushed this letter in order for it to be mailed and postmarked the same day. Unless, he had prepared it days earlier, just after the murder of Robert Salem and deliberately timed to coincide with the San Francisco Chronicle newspaper coverage. 

The police claimed that the "killer was not Zodiac", but with the parallels drawn from the authenticated Melvin Belli letter regarding the murder of Frances Brown - that a copycat would have been hard pushed to extrapolate - does this make the assertion that this was not a Zodiac crime by police, a rather over-confident statement just five days after the murder?  

The 408 cipher, mailed in three parts to the San Francisco Chronicle, San Francisco Examiner and Vallejo Times-Herald on July 31st 1969 had 18 unsolved characters at its foot. However, the Zodiac Killer likely made an error when transferring his original message into the encrypted version, accidentally omitting the word "people" from the section of code mailed to the San Francisco Chronicle: "The best part of it is that when I die I will be reborn in paradice and all the (people) I have killed will become my slaves". Had he transferred the message correctly, the intended version would have had only 12 unsolved characters in which his identity may have resided, such as "I am the Zodiac". After all, he promised us his identity not his name. What are the chances the Zodiac Killer left a similar message at the foot of the 340 cipher?

Professor D.C.B. Marsh, in the October 22nd 1969 San Francisco Examiner newspaper article by Will Stevens, laid down a challenge to the Zodiac Killer to reveal 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 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 - however complicated - which will truly and honestly include his name". It was speculated that the Zodiac Killer certainly wasn't going to provide another conventional cryptogram to be easily decoded, so instead created the appearance of a cryptogram with hidden "puzzles" contained within it, such as "paradice" and "slaves" running vertically and horizontally across its mid-section. This was later revealed in the 'Halloween' card, where the Zodiac Killer belatedly informed us the 340 code was "sorry no cipher" and placed "paradice" and "slaves" in a cross formation to point us in the right direction.   

The "sorry no cipher" section of the 'Halloween' card has one section running from bottom to top. The '13 Hole' postcard mailed before this offering has "Fk I'm crackproof" flipped upside down. This gave rise to the idea that the 340 cipher needed to flipped vertically, which I was able to do on Dave Oranchak's excellent Webtoy on the Zodiac Killer Ciphers website. 

​When Professor D.C.B. Marsh laid down the challenge to Zodiac, it was initially considered that the message at the foot of the 340 cipher may have teased the American Cryptogram Association with something like "next time I will tell you who the Zodiac is", bearing in mind where the near-pseudonym was placed. Then, five months later he would follow this up with the reveal of his name, which he effectively teased us with by stating "This is the Zodiac speaking. By the way have you cracked the last cipher I sent you. My name is...."  

This statement is very telling, when we consider that it was patently obvious that his last cipher hadn't been solved - so why did he add this to the opening of the April 20th 1970 communication? The final section of the 340 cipher may explain why he began this correspondence in the way he did. It may be conceivable that the last section of the 340 cipher promised to reveal his name in the next cipher, hence the blatantly obvious introduction in the April 20th 1970 communication, of "This is the Zodiac speaking. By the way have you cracked the last cipher I sent you. My name is...."  We effectively have to bridge the gap between "I am the Zodiac" (if correct) on the 408 cipher to "My name is" on the April 20th letter. The obvious connector would be the promise of a new cipher or code containing the Zodiac Killer's name. 

It is notable that the 340 cipher begins with "her" (the last three letters of cipher), however, it is impossible to form the word "cipher" in the format offered. The uniform 17 X 20 pattern of the cipher would be broken by adding "cip" to the beginning. For this section to provide us with the word "cipher" within the existing pattern and the promise of a new cipher containing the Zodiac's name, the 340 cipher has to be flipped - possibly as the 'Halloween' card and '13 Hole' postcard had hinted nearly a year later. Other than the 408 cipher mailings, every other Zodiac correspondence began with the introduction of "This is the Zodiac Speaking". The 340 cipher, when flipped, enables this introduction to begin the 340 character message also. ​ 

But what is the likely message encoded at the foot of the cipher? Without having decoded it, I can only make a calculated guess from other Zodiac correspondence. In the August 4th 1969 'Debut of Zodiac' letter, the killer wrote "By the way, are the police having a good time with the code? If not, tell them to cheer up; when they do crack it, they will have me".  

In the April 20th 1970 communication, the killer wrote "By the way have you cracked the last cipher I sent you. My name is...." 

Therefore, I will use the literal words of the Zodiac Killer to complete the last 27 characters of the 340 cipher, obviously changing "last" to "next".
​
By flipping the 340 cipher vertically we are able to use the clue of "Zodiac" to generate his usual introduction and then form the bridge between cipher one and cipher three with the promise of his name in cipher two, using the words of the Zodiac Killer himself. Whether this analysis has any semblance of truth is another matter entirely. 

Here I would like to return to an old topic with a fresh approach, partly inspired by 'Nobody,' a regular contributor to this site.
As early as August 10th 1969 Professor D.C.B. Marsh of the American Cryptogram Association (ACA) was commenting on the Zodiac ciphers. In the San Francisco Sunday Examiner & Chronicle he praised Donald Harden's deciphering skills and called the code "complicated and obviously drawn by somebody who knows his business". 
​
The Zodiac Killer had already responded to prompts by Vallejo Police Chief Jack Stiltz to send more details to prove the letter writer and killer were one and the same. The more the Zodiac Killer wrote, not only lessened his time for killing, but may have provided additional clues to detectives regarding his identity. This tactic was likely adopted by Professor D.C.B. Marsh in the October 22nd 1969 San Francisco Examiner newspaper article by Will Stevens, which laid down a challenge to the Zodiac Killer to reveal 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 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 - however complicated - which will truly and honestly include his name".

Clearly, Dr. Marsh and the detectives would have considered it highly unlikely for the Zodiac Killer to respond by giving us his name, but while he was constructing ciphers he wasn't murdering innocent civilians. There also remained an outside chance that Zodiac would rise to the challenge and create a code, "however complicated", that Dr Marsh and his fellow cryptographers could unpick. This article, rather than a straightforward challenge to Zodiac, could have been deliberately manufactured with the assistance of detectives to bait the Zodiac Killer into using a particular methodology in his cipher construction. If the police knew the source of Zodiac's inspiration then it could unearth the cipher technique he employed when designing his next code. 

'Nobody' considered the idea that the Zodiac Killer may have used a foreign language in the cipher or possibly a rotating key that switches at certain intervals. By employing such a technique the Zodiac Killer could make the cipher virtually "crackproof". The article in the October 22nd 1969 San Francisco Examiner may have been specifically designed to lead the Zodiac Killer down a particular path, making his next cipher easier to crack. Dropping innocuous sections of text into an article such as "to quote Edgar Allen Poe, that any cipher created by man can be solved by man", can be specifically designed to guide the Bay Area murderer into using one of Edgar Allan Poe's cipher techniques or a model suggested by him. We know the Zodiac Killer was an avid reader of the newspapers and may have took this bait of using a publication by Edgar Allan Poe, thinking he was getting one over on Dr Marsh and the police. The hope from the standpoint of law enforcement was that the Zodiac Killer would bite the hook and get reeled in. 

Sixteen days later the Zodiac Killer mailed the 340 cipher revealing, not his name, but his identity, carefully positioned at the base of his cipher. This catapulted the idea that the Zodiac Killer had indeed responded to the article by Dr Marsh but wasn't quite ready to reveal his name to authorities. But it is my belief that the Zodiac Killer did create the 340 and 13 Symbol ciphers in tandem with a view to inextricably link his identity to his name using the word "Zodiac" on the final row of the 340 cipher, with the three 8's as the conduit between the two. See here.

The Zodiac Killer, however, would hold back his '13 Symbol' cipher for approximately six months. Zodiac researcher Michael Cole stated "Clearly, the Zodiac did not send the cryptogram to Marsh, as had been requested (this non-public way of satisfying the challenge was apparently unacceptable to the attention-craving serial killer). Neither did he respond in a time frame that most would have expected. But these details matter little. In fact, the timing itself provides yet another reason to conclude that what we have here is a specific instance of cause and effect. As mentioned, this article was published in the Examiner on October 22, 1969.  Six months to the day later, April 22, 1970, the people of the San Francisco Bay Area were reading about the My Name Is cipher in the Chronicle".

But there may have been a much more cunning reason why the Zodiac Killer delayed his mailing of the April 20th 1970 communication, and it has everything to do with Edgar Allan Poe. Did the Zodiac Killer pick up on the wording of Dr. D.C.B. Marsh in the article, and create and mail his '13 Symbol' cipher based on something in the writings of Edgar Allen Poe? 

We can see in the Edgar Allan Poe essay 'A Few Words on Secret Writing,' at the very beginning he shows the alphabet being split into two halves of 13 letters, A to M, and N to Z.
"Were two individuals, totally unpractised in cryptography, desirous of holding by letter a correspondence which should be unintelligible to all but themselves, it is most probable that they would at once think of a peculiar alphabet, to which each should have a key. At first it would, perhaps, be arranged that a should stand for z, b for y, c for x, d for w, &c. &c.; that is to say, the order of the letters would be reversed. Upon second thoughts, this arrangement appearing too obvious, a more complex mode would be adopted. The first thirteen letters might be written beneath the last thirteen, thus:
n o p q r s t u v w x y z
a b c d e f g h i j k I m; and, so placed, a might stand for n and n for a, o for b and b for a, &c. &c. This, again, having an air of regularity which might be fathomed, the key alphabet might be constructed absolutely at random." ​​

The Zodiac Killer not only created the April 20th 1970 cipher with 13 characters, but it too began with an A and ended with an M, just like the suggested encryption technique featured by Edgar Allan Poe. Notice the way the cipher is organized symmetrically using the alphabetical characters, the three 8's and the two symbols. The same symmetry was observed when placing half the alphabet alongside the 13 character cipher. See here.  

The Dr. Marsh newspaper article opened with "A Challenge perhaps unique in the annals of American crime was injected today into the bizarre case of the killer who begins his letters to newspapers This is the Zodiac Speaking". The article continued, and bemoaned the fact that Zodiac hadn't revealed his true identity: "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".

'A Few Words on Secret Writing' stated "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". ​link. 

If the Zodiac Killer was basing the '13 Symbol' cipher on the Dr. Marsh article and secret writing of Edgar Allan Poe, why did he wait approximately six months to mail it to the San Francisco Chronicle? It may not have been the six month anniversary that was important to him, but the only date mentioned in the Edgar Allan Poe literature, 'A Few Words on Secret Writing'. The date was April 21st. Had the Zodiac Killer deliberately waited six months to ensure his '13 Symbol' cipher letter would be postmarked April 21st, or be published on April 21st, which unfortunately for him never materialized? He was slightly early on the mailing, resulting in the postmark of April 20th - with the San Francisco Chronicle publishing his cipher in the April 22nd edition, effectively thwarting any intentions to recreate the Connecticut letter.

However, the possibility remains that the Zodiac Killer could have used one of the cipher techniques employed or suggested by Edgar Allan Poe in 'A Few Words on Secret Writing' - and the idea proposed by 'Nobody' regarding the use of a second language as the key, a much more viable proposition than initially considered.
​
"It is not to be supposed that Cryptography, as a serious thing, as the means of imparting important information, has gone out of use at the present day. It is still commonly practised in diplomacy; and there are individuals, even now, holding office in the eye of various foreign governments, whose real business is that of deciphering. We have already said that a peculiar mental action is called into play in the solution of cryptographical problems, at least in those of the higher order. Good cryptographists are rare indeed; and thus their services, although seldom required, are necessarily well requited. An instance of the modern employment cipher is mentioned in a work lately published by Messieurs Lea & Blanchard, of this city–“Sketches of Conspicuous Living Characters of France.” In a notice of Berryer, it is said that a letter being addressed by the Duchess de Berri to the legitimists of Paris, to inform them of her arrival, it was accompanied by a long note in cipher, the key of which she had forgotten to give. “The penetrating mind of Berrver,” says the biographer, “soon discovered it. It was this phrase substituted for the twenty-four letters of the alphabet–Le,gouvernement provisoire". 'A Few Words on Secret Writing' by Edgar Allan Poe.

Robert Michael Salem's body was discovered by friends on the evening of Sunday April 19th 1970 at his 745 Stevenson Street, San Francisco residence. The autopsy concluded he had died on Wednesday April 15th. The article below was published in the San Francisco Chronicle on the morning of April 20th 1970. This is the same day that Zodiac's '13 Symbol' cipher communication was postmarked, proclaiming "I hope you have fun trying to figgure out who I killed."​​​
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Bearing in mind this article was considering a Zodiac connection, did the Bay Area murderer respond by creating this letter and mailing it almost immediately. The killer hadn't written since the 'Melvin Belli' letter on December 20th 1969, exactly 122 days ago. Therefore, do we conclude that [1] the Zodiac Killer just happened to independently write the April 20th 1970 communication, which accidentally coincided with the April 20th 1970 San Francisco Chronicle article, but he wasn't the murderer of Robert Salem. [2] He was the murderer of Robert Salem and had prepared the letter from the time of his death on the 15th, before mailing it on the 20th, or [3] He immediately sprang into action on April 20th 1970 after reading the article, and created the '13 Symbol' cipher in double quick time, designed his 'photoelectric switched' bus bomb diagram, and recalled the murder of San Francisco police officer Brian McDonnell on February 16th 1970, all in time to have this letter postmarked on the same day. To answer this question we have to go back six months. 

Michael Cole wrote an excellent article entitled "My Name Is" Cipher Motivation that suggested the Zodiac Killer likely drew his inspiration for the '13 Symbol' cipher from an October 22nd 1969 newspaper article by Will Stevens, which laid down a challenge to the Zodiac Killer from the president of the American Cryptogram Association (ACA), Professor D.C.B. Marsh, to reveal his name. Apparently, several months later the killer duly obliged by opening his correspondence with the line "This is the Zodiac speaking. By the way have you cracked the last cipher I sent you. My name is...."

Michael Cole wrote "Clearly, the Zodiac did not send the cryptogram to Marsh, as had been requested (this non-public way of satisfying the challenge was apparently unacceptable to the attention-craving serial killer). Neither did he respond in a time frame that most would have expected. But these details matter little. In fact, the timing itself provides yet another reason to conclude that what we have here is a specific instance of cause and effect. As mentioned, this article was published in the Examiner on October 22, 1969.  Six months to the day later, April 22, 1970, the people of the San Francisco Bay Area were reading about the My Name Is cipher in the Chronicle. This relationship between the Examiner article and the My Name Is cipher may well mean there is an even higher likelihood that the cryptogram does indeed encipher some form of the killer's name"

If the April 20th 1970 letter was referring to the Robert Salem murder, by teasing us with the statement "I hope you have fun trying to figgure out who I killed"​​​, then any manufactured correlation between the dates by the Zodiac Killer would rely on the Zodiac Killer committing the murder just shy of the six month anniversary and then mailing the letter. This would mean the Zodiac Killer could prepare the letter in the days between the murder and the mailing date of April 19th or 20th, to enable it to be postmarked on the 20th. If he didn't kill Robert Salem, and was simply responding to the San Francisco Chronicle with an unprepared letter, then his code and bus bomb diagram must have been designed with little forethought, and mailed in time to be franked on the same day. The other possibility, is he had the code and bus bomb diagram already prepared in advance and just added the text around these designs. However, there is one major problem. The photograph of the crime scene wasn't shown until a follow up article by Paul Avery in the San Francisco Chronicle on April 21st 1970. By which time, the Zodiac Killer had already mailed the letter.               

It has previously been argued that the Zodiac Killer created the '13 Symbol' code in tandem with the 340 cipher, a matter of weeks after the October 22nd 1969 challenge by the American Cryptogram Association (ACA) and Professor D.C.B. Marsh. 
The reason behind this claim was the correlation between eight characters on the final row of the 340 cipher and eight characters from the '13 Symbol' cipher (six being the circled eights).   

On the left we have lined up the alphabet over the top of the cipher. Now calculate numerically the difference in each column. ie: C to N produces a difference of 11, whereas B and E produces a difference of 3. Non alphabetical symbols cannot produce a difference, so a zero is inserted. The resulting numbers produced have been color coded. The red section is before the first circled 8, the green section is after the last circled 8 and the blue section spans the first and last circled 8. Notice the perfect symmetry. The red and green numbers are identical read forwards or backwards, and the blue numbers again read identically in either direction, producing a mirror image. Is this a coincidence or is it by design. 
​
The 340 Cipher was the Zodiac Killer's unsolved masterpiece, and being a man with an inflated ego, driven by self publicity, what better way to drop us a hint by placing his signature or pseudonym on the final line of the 340 Cipher. You will notice he placed the Zodiac crosshair symbol, followed by what could be interpreted as Zodiac and then an upside down Aries symbol, with a line on the top and a dot to the left. So what we shall do is place the correct spelling of Zodiac alongside the version he placed on the 20th line of the 340 Cipher and use the identical technique we used to create the symmetry on the '13 Symbol' cipher. The alphabetical difference of ZOD produces three zero's, the IAC produces 888. These two sets of figures incorporated gives us the three circled 8's found on his next cipher, as though he was carrying them forward. It is also apparent on the '13 Symbol' cipher that either side of the three circled 8's are the Zodiac crosshairs and an inverted Aries symbol, identical to the final line of the 340 Cipher. So, the author has effectively carried eight symbols from one cipher to another.

"In Christian numerology, the number 888 represents Jesus, or sometimes more specifically Christ the Redeemer. This representation may be justified either through gematria, by counting the letter values of the Greek transliteration of Jesus' name, or as an opposing value to 666, the number of the beast." Wikipedia.

The ZOD and IAC are separated. The first produces the 000. The second produces the 888. The two are then combined, to create the transition from the 340 cipher to the '13 Symbol' cipher. This was presumably designed by the Zodiac Killer when he created the 340 cipher sometime before November 8th 1969, with a view to his next cipher. 

When the Zodiac Killer mailed the April 20th 1970 letter and code (assuming he wasn't the killer), he hadn't seen the way Zodiac was written on the wall of Robert Salem's apartment. Therefore, did the killer of Robert Salem just accidentally separate the ZOD and IAC of ZODIAC, thereby mimicking the Zodiac Killer's 340 cipher creation, when he had ample room on the wall to write it normally, or was the Zodiac Killer present at the 745 Stevenson Street, San Francisco residence on April 15th 1970, giving him the opportunity to create the design, and at least five days to prepare his letter? The April 20th 1970 code being the confirmation of his involvement in the murder. 
Was this the reason for the wording "I hope you have fun trying to figgure out who I killed"?

The crucified image on the wall of Robert Salem's wall may well be the Egyptian ankh. The ankh appears frequently in Egyptian tomb paintings and other art, often at the fingertips of a god or goddess in images that represent the deities of the afterlife conferring the gift of life on the dead person's mummy; this is thought to symbolize the act of conception. 
​Wikipedia.

In the last three articles it was proposed that the author of the 408 cipher may have left his identity within the final 18 characters. He specifically told us that he would not give us his name, but assured us his identity was concealed within the cipher - reasoned to be something like "I am the Zodiac Killer." The theme of his identity and name were integral to the final third of the cipher and letter mailed to the San Francisco Chronicle on July 31st 1969, and may very well have manifested through both his second and third ciphers as well. The third cipher began with "This is the Zodiac speaking. By the way have you cracked the last cipher I sent you. My name is...."- therefore, the final line of the second cipher (340 cipher) may be the 'narrative bridge' between the first and third cryptic offerings. 

The first cipher achieved everything the Zodiac Killer had wished for. He had fashioned using threats and newspaper rivalry maximum exposure for his handiwork, which was very quickly published by the Vallejo Times-Herald, San Francisco Examiner and San Francisco Chronicle. The failure of Zodiac to give us his name did not satiate the desire of some in the quest for the real identity of the killer, and was championed by Dr D.C.B. Marsh, president of the American Cryptogram Association, who on October 22nd 1969 in an article published by the San Francisco Examiner, stated "The killer wouldn't dare, as he claimed in letters to the newspapers, to reveal his name in a cipher to established cryptogram experts. "Zodiac" had not done this, Marsh suggested, 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."

​This article was not to go unnoticed by the killer, who, two and a half weeks later mailed his infamous 340 cipher, unsolved to this day according to official sources. This cipher was to become the all-important bridge between cipher one and three. If he gave us his identity (the Zodiac Killer) in the unsolved 18 characters of cipher one, and stated "my name is" in cipher three (supposedly giving us his name), then by logical extension, cipher two should have been the promise of a name, and the conduit between the two.

If we can provide a compelling reason to show that the near-Zodiac on the final line of the 340 cipher was actually intended to be deciphered to 'Zodiac', then we are left with the final two characters of the cipher to decode, thereby bridging the gap between cipher two and three. 
Using the most powerful supercomputers in the world and the talent of some of the brightest minds in cryptography, the 340 cipher has failed to buckle. So, it's time to use the character of the Zodiac against himself, and his willingness to respond to the newspapers.

If the Zodiac Killer is responding to Dr D.C.B. Marsh, then he clearly isn't prepared to give us his name immediately in the November 8th 1969 '340 cipher', as the opening line in his April 20th 1970 communication would testify to. It would be over five months later that he stated "my name is".  Therefore, the final two characters of the 340 cipher are the conclusion to an open-ended promise of something more to come, in similar fashion to "my name is."  The Zodiac Killer certainly wasn't going to miss the opportunity to keep Dr D.C.B. Marsh and the public waiting just a little bit longer. 
​
The final line or sequence of the 340 cipher probably read "The next cipher will reveal who the Zodiac is" or "I will soon reveal who the Zodiac is" - or something along these lines. This 'promise' can be seen in his opening gambit of the April 20th 1970 communication: "This is the Zodiac speaking. By the way have you cracked the last cipher I sent you. My name is...." ​
The statement of "by the way have you cracked the last cipher I sent you" is superfluous, as he knows only too well the 340 cipher has not been cracked, yet, it also lacks his usual abrasive sarcasm. However, it is followed by "my name is", and therefore could be construed as the conclusion to his promise from the final line of his 340 cipher and to Dr D.C.B. Marsh, and the allegorical  bridge between the two ciphers.

But how do we know that the near-Zodiac on the final line of the 340 cipher was to be decoded to 'Zodiac'?  Because he fashioned a bridge between cipher two and three using his pseudonym. Placing the real spelling of Zodiac under the '340 cipher' version of Zodiac, and counting the alphabetical difference numerically between the columns (see here), we achieve the numbers 000888. When combined, the three circled 8's found on the '13 Symbol' cipher.
​
These six characters of the 340 cipher were effectively carried forward numerically and placed front and center of the '13 Symbol' cipher design. You will also notice that the two characters either side of three 8's (shown on the right), are both visible either side of the near-Zodiac on the 340 cipher. A total of eight characters and three circled 8's the common link or bridge between cipher two and three - in which the name of Zodiac played a pivotal part in the formation of the 'My Name is Cipher'. The story is now complete. 

The Zodiac Killer stated on July 31st 1969 "I will not give you my name, but in this cipher is my identity." He promised in the 340 cipher, in a response to Dr D.C.B. Marsh, that he would soon reveal his name. Then, five and a half months later, on April 20th 1970 he stated "This is the Zodiac speaking. By the way have you cracked the last cipher I sent you. My name is...." 

Do ciphers two and three really contain a full and coherent message, not dissimilar to the 408 cipher solution, or had the Zodiac Killer taken Dr D.C.B. Marsh's advice "to send The American Cryptogram Association a cipher code - however complicated", and taken it a step too far?