The most detailed description of the Zodiac Killer was presented in the days after the murder of Paul Stine in Presidio Heights, likely arrived upon by an amalgamation of two sets of eyewitnesses. The final age range estimated at between 35-45 years of age and semi-corroborated by Officer Donald Fouke, who described the suspect as 'graying in the rear' in his November 12th 1969 memorandum. The age of the killer may be relevant, when we consider the dramatic change in writing style from November 29th 1966/April 30th 1967 to the beginning of the Zodiac letters in 1969, just two years later. Is it possible to examine the linguistics from correspondence in the Cheri Jo Bates murder to the later writings and determine if they were authored by the same individual?  

The Zodiac Killer never bragged or labored the point about his four canonical attacks or five murders with respect to the victims. The closest he came was describing the attack on Michael Mageau, stating "When I fired the first shot at his head, he leaped backwards at the same time, thus spoiling my aim. He ended up on the back seat then the floor in back thashing out very violently with his legs; that's how I shot him in the knee."  But on this occasion he was prompted for more details about the crimes by Vallejo Police Chief Jack Stiltz, and duly responded. 
However, in the 'Confession' and Bates letters, just 2 to 3 years earlier, the author seemed to be relishing in the pain and misery he inflicted on Cheri Jo Bates and her family.
With statements such as "I said it was about time for her to die, she squirmed and shook as I chocked her and her lips twiched, and I then finished the job out cutting her throat," it had all the hallmarks of a killer who enjoyed reliving the events of that night, as well as exacerbating the heartbreak and suffering felt by family and friends. The author, not only named his victim in both letters, something the Zodiac Killer always steered away from, but he also mailed a letter to the father of the victim, Joseph Bates.
The addresses of the victims in the Zodiac crimes were routinely published in the newspapers, yet the Bay Area murderer failed to make contact with any of the victims families through mailed correspondence. The killer seemed to almost depersonalize the victims, only referring to them as kids, teenagers, boy, girl, woman, man, taxicab driver and people. When it came to his adversaries such as newspaper reporters, columnists, attorneys and police, then he had little problem naming Paul Avery, Marc H Spinelli, Herb Caen, Melvin Belli and David Toschi (depending on the validity of the correspondence).
Were the crimes simply his requirement to be taken seriously, so he could begin his letter writing campaign? In other words, they were not his primary focus, and why the attacks apparently ended after only 10 months.  

The most sexually explicit reference in the confirmed Zodiac letters was his statement of "man is the most dangerous animal of all to kill something gives me the most thrilling experience it is even better than getting your rocks off with a girl" in the deciphered 408 cryptogram. However, even this is downgrading sex below murder.
The 'Confession' letter is altogether different, referencing lying awake thinking about beautiful women, stating "Her breast felt very warm and firm under my hands, her lips twiched, keep your sisters, daughters and wives off the streets and alleys, I shall cut off her female parts and deposit them for the whole city to see and I am stalking your girls now." 
The emphasis of the letter is based solely on women, not couples, men or children. It also has a sexual component, not particularly evident in the Zodiac letters.
On March 13th 1971 the Zodiac Killer part-indicated his involvement in the Riverside murder of Cheri Jo Bates, but even then he couldn't refer to her by name - something he supposedly had no problem doing in both the Riverside correspondences a few years earlier. So, was the Riverside murderer really the Zodiac Killer?    ​

On the morning of October 31st 1966 at 6:30 am, Cleophus F. Martin (49), a groundskeeper at the Riverside City College discovered the stricken body of Cheri Jo Bates in an alleyway between two vacant properties. He was also described as a janitor on the website Find A Grave. Cleophus Martin died in 1975. Whether or not he is the same person who discovered the 'Riverside Desktop Poem' is open to speculation. Four years earlier, on February 28th 1962, the San Bernardino County Sun ran an article entitled 'San Bernardino Youth Knifed in Wild Attack on Redlands Road'. Here is the article text.    

"Three men were held for questioning in the knifing of a 19-year-old San Bernardino youth Monday after a highway incident that wound up in a wild, four-mile chase with occupants of one vehicle throwing rocks and debris at the other vehicle.
Charles Albert Schuler, 19, of 7695 Merito Avenue, was treated at Community Hospital for cuts on the shoulder, right elbow and left hand that he said was inflicted by a curved flooring knife.
His companions, Perry Lee Thomas and Bill Roan, both of San Bernardino, and Robert Claude Cockrell said they were attacked at Highway 99 and Alabama Street on the outskirts of Redlands about 5 pm Monday.
They said their three assailants, occupants of a pick-up truck, pushed in the windows of the hardtop in which the four were riding, and one of the assailants shoved in a pocket knife and started swinging it.
The four said they then got out of their car, but were chased by the other three, all of whom had knives. Witnesses said that Schuler was chased through heavy traffic. His shirt was cut to ribbons by his knife-swinging assailant.
After dodging knives for a while, the four youths got back in their car and fled. They said the three in the pick-up truck loaded the truck bed with rocks and debris, and chased the car four miles to Tippecanoe and Central.
One of their assailants rode in the truck bed and the other on a running board, hurling rocks and debris at the car, the four said. The truck was identified through a license number and three men were later picked up by Detective Jay D. Hughes.
Booked in the County Jail for questioning were Booker T. Washington (47), his son, John T. Washington (26) and Cleophus Martin (43) of 1577 Vine Street, all of San Bernardino. Detective William Paterson of the homicide division is investigating."   

Cleophus Martin was born on 15th October 1917, which would have him 44 years of age on February 28th 1962, not 43, as referenced in the newspaper. Due to the rarity of the name and the location of San Bernardino, it could be argued that this was the groundskeeper/janitor who discovered the body of Cheri Jo Bates. This man likely had nothing to do with the murder of Cheri Jo Bates, and was unfortunate enough to discover the terrible events of the previous night, nevertheless, it begs the question of how familiar the perpetrator was in respect to the Riverside City College campus.

Was the murderer of Cheri Jo Bates familiar enough with the Riverside City College campus to know that the two properties either side of the attack site were empty? Did he have access to the Riverside library storage room to write on the underside of the desktop in relative anonymity? Did he use paper acquired from the Riverside college?  "A photocopying machine, where students could secure 8 1/2 X 11 inch black and white copy of printed or typed material, was available at the library for ten cents." The photocopying machine would have been acquired by the college library to accommodate the paper likely used by the college staff and students. The three Bates letters mailed on April 30th 1967 measured 8 1/2 X 11 inches, identical to the size offered by the photocopier in the library. 

Credit to ZodiacKillerIdentified on Youtube.

When Stephanie Guttman turned down the opportunity to accompany Cheri Jo Bates to the Riverside City College library on the afternoon of October 30th 1966, did she make alternative arrangements that ultimately led to her early demise. Despite entering the library to acquire her reading material shortly after opening time, she left within minutes. Nobody remembers seeing the young girl from 6:30 pm to 9.00 pm that evening, indicating she exited the library and went elsewhere. She wasn't murdered until approximately 10:30 pm that night, when screams were heard in the vicinity of the alleyway. At approximately 9:30 pm a female student purportedly noticed a man standing in the fateful alleyway smoking a cigarette and exchanged brief greetings with him. It is therefore clear that Cheri Jo Bates had been murdered subsequent to this encounter. The following observations take a new approach to the murder of Cheri Jo Bates, based upon the structure and wording of the 'Confession' letter mailed one month later. 

Everything contained in the 'Confession' letter was information readily available in the newspapers, however, this doesn't necessarily indicate that the author of the letter wasn't the killer. But there is a narrative in the letter that completely flies in the face of what was possible. The author of the 'Confession' letter described the middle wire of the distributor being pulled, the small knife and the cutting of the throat, which were all reported in the newspapers and totally correct, yet gave the impression that everything happened in one continuous timeline, which was impossible. The impression given, is of a woman who enters the library while her vehicle is being disabled, and then exits to find her car won't start. The good Samaritan then offers her assistance and escorts her to a promise of a lift in his vehicle just down the street, before stabbing her. We know Cheri Jo Bates wasn't murdered between 6:00 pm and 9:30 pm, so why does the author cover all his bases in convincing the reader he is the killer, but fail so horribly with the timeline?

Many details of the crime were printed in the newspapers, including an "awful scream between 10:15 pm and 10:45 pm and then a loud sound like an old car starting up". The author of the letter uses this scream in his letter, stating "she let out a scream once and I kicked her in the head," along with the presence of his vehicle: "I told her that my car was down the street and that I would give her a lift home".  However, if he knew she had exited the library to find her car disabled, then his story doesn't work from the standpoint of a 10:15 pm to 10:45 pm attack, as the library closed at 9:00 pm. Besides, he stated he followed her out of the library after about 2 minutes, and we know she left prior to 6:30 pm. Why is the author (if the killer) trying to give the impression that Cheri Jo Bates never left the campus that evening, when clearly her movements were unknown for approximately 4 hours?

The author blatantly disregards the time of 10:15 pm and 10:45 pm in his continuous timeline, but certainly makes use of the scream and vehicle, to give us the impression he had killed Cheri Jo Bates moments after she exited the library. Does he weave his vehicle into the story to convince us he had to travel a reasonable distance to arrive near the alleyway, and therefore lives a reasonable distance away, when in actual fact he lived within walking distance of the Riverside campus. If the author of the 'Confession' letter was the Zodiac Killer, he may have used this tactic nearly three years later, when using his vehicle as evidence he didn't live close to the payphone at Springs and Tuolumne after the attack at Blue Rock Springs.

If Cheri Jo Bates had left the library annex voluntarily before 6:30 pm and hooked up with somebody who lived nearby - who then escorted her back to her vehicle at around 10:30 pm, then the disabling of her vehicle could have taken place while she was present during an altercation. This would explain both windows rolled down, the right door being possibly ajar and the keys present in the ignition. A murder at approximately 10:30 pm with little passing traffic is an altogether more likely scenario, particularly when we consider the screams heard by eyewitnesses.

The author and killer would have been unaware at the point of writing, of a female student and man present in the alleyway with no body, and was desperate to shift the timeline 4 hours earlier, thereby ruling out any possibility of Cheri Jo Bates having ever left the campus to a nearby residence with somebody she knew. The use of his vehicle in the letter was the window dressing, to paint a completely different picture to the one that really happened that night - that Cheri Jo Bates was escorted from the campus on foot at around 6:30 pm by somebody she trusted. Somebody that would eventually betray that trust a mere 4 hours later.

Zodiac researchers Michael Morford, David Oranchak and Michael Butterfield sat down with House of Mystery Radio - KKNW Seattle to produce a four part roundtable discussion about the 'unholy trail' of the Zodiac Killer. Each podcast, presented on the Youtube platform, is split into four 50 plus minute segments.
 
Part One - Zodiac Killer Roundtable

Part Two - Zodiac Ciphers 

Part Three - Zodiac Killer Letters 
​
Part Four - Cheri Jo Bates

The Zodiac mailed correspondence to the San Francisco Chronicle on April 20th 1970, in which he stated "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." Suisun City, Solano County, California can be seen via the link to border the city of Fairfield. But why is this relevant?

It has been suggested in previous articles that the Zodiac Killer may have resided near the payphone at Springs Road and Tuolumne Street, but we know that three letters were mailed from Fairfield to the San Francisco Chronicle on December 7th 1969 and in the middle of 1971 (possibly May) and to the San Francisco Examiner on December 16th 1969. These were genuine Zodiac letters, so there is a possibility that he may have been a resident of Suisun City or Fairfield for the duration of the 7th to 16th of December and mailed his letters from this location. Was he a resident of this area beyond December 16th 1969, or did he reside here permanently? The Bay Area murderer may have had two residences, a vacation home, lockup or a business in this region of Solano County. 
​
Just a matter of weeks after the final Fairfield letter, floods in Suisun City/Fairfield, "from Laurel Creek and Union Avenue Creek caused flooding in January 1970" resulting in the evacuation of many "residences and businesses" in the area. The Zodiac Killer then wrote to the San Francisco Chronicle in April, stating "that my bus bomb was a dud.  I was swamped out by the rain we had a while back." But was he telling the truth?  

# The population of Suisun City was only 2,917 in 1970.
# The population of Fairfield was 44,146 in 1970.

It is important when we examine the writings of the Zodiac Killer to view them in context to the news breaking during the time in which he put pen to paper. The 1970s were a turbulent period in San Francisco and the Zodiac certainly monopolized on this fact in at least three of his communications pertinent to this story. The Zodiac Killer also had a penchant for adding historical references to his material in order to convey the message. The Mikado by Gilbert & Sullivan, a Tim Holt comic book, The Most Dangerous Game by Richard Connell, and surprisingly, Moby Dick by Herman Melville to name but a few. To believe the Zodiac Killer's bomb threats may have been inspired by a man who borrowed the Moby Dick author's name, may take a bit of selling.

Samuel Joseph Melville was the principal conspirator and bomb setter in the 1969 bombings of eight government and commercial office buildings in New York City. He was born Samuel Joseph Grossman, but changed his name with respect to novelist and poet Herman Melville. ​He had already committed four bombings prior to the November 9th 1969 Zodiac 'Bus Bomb' letter. It began with Grace Pier on July 27th, followed by August 20: Marine Midland Building, September 19: Federal Plaza and then an Army Induction Center on October 7th. These crimes received statewide coverage throughout America, but were they an inspiration to the Zodiac Killer in the power of large scale destruction as a tool for terror. The answer may have come five and a half months later. But first we shall take a look at the April 20th 1970 letter, which stated "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".
 
We know that the Zodiac Killer often referenced newspaper headlines - and this communication would be no different - denying his involvement in the murder of San Francisco police officer Brian McDonnell (44) on February 16th 1970. Person or persons unknown had placed a pipe bomb packed with fence staples on the window ledge of Park Police Station in Upper Haight (1899 Waller Street). Another eight police officers were also injured. The Zodiac Killer was unlikely to have had any involvement in the bombing, however, he was keen to suggest that he was capable of such an act, but for "the rain we had a while back". Two weeks prior to the April 20th 1970 Zodiac letter, on April 6th 1970, the deadliest day in the history of California law enforcement occurred, when two armed criminals managed to kill four California Highway Patrol officers in just under 5 minutes. Known as the Newhall Massacre, it hit the newspaper stands around the country.

One can't help thinking the Zodiac Killer was fully aware of this tragedy, when he cynically penned the words "there is more glory in killing a cop than a cid because a cop can shoot back".  Or maybe, we give the Zodiac too much credit. The Zodiac Killer may not have killed Sgt. Brian McDonnell on February 16th 1970, but his following correspondence on April 28th 1970, just eight days later, would certainly coalesce both Sam Melville and Park Police Station under one banner, when he wrote "If you dont want me to have this blast you must do two things. Tell everyone about the bus bomb with all the details. I would like to see some nice Zodiac buttons wandering about town. Everyone else has these buttons like, black power, melvin eats bluber, etc. Well it would cheer me up considerably if I saw a lot of people wearing my buton. Please no nasty ones like melvin's. Thank you". 

The phrase "melvin eats bluber" was referring to the prominent lawyer and bon vivant Melvin Belli, who had earlier become the focus of one of Zodiac's letters. The Zodiac was referring to the 1960s fad buttons created by Irwin Weisfeld, but had altered the slogan from "Melville Eats Blubber" (Moby Dick) to "Melvin Eats Bluber".
Bearing in mind the introduction and tone of this card: "I hope you enjoy yourselves when I have my blast," and his choice of counterculture button, the following connection cannot be ignored. ​The Zodiac borrowed the Melville Eats Blubber button and changed it for purpose, as did Sam Melville, when altering his name from Grossman to Melville before his bombing campaign. The crucial question, however, is where did Zodiac intend to have this "blast". The clue may be staring us square in the face (see image on right).

The Zodiac Killer wrote "I hope you enjoy yourselves when I have my blast" around the picture of Don Quixote and Sancho Panza, the characters in a novel by Miguel de Cervantes Saavedra. These characters are situated only 3,650 feet (0.68 miles) from the murder site of Sgt. Brian McDonnell, both of which are situated in Golden Gate Park. The Zodiac Killer, almost certainly, never had any intention of placing a bomb near the Don Quixote and Sancho Panza statue in Golden Gate Park, but the fact that this statue was in such close proximity to the bombing of Park Police Station on February 16th 1970, could be interpreted as a mischievous and insensitive offering to police. He was effectively rubbing their "noze in their booboos".

Then came the possible threat on Ingleside Police Station, two months later, on June 26th 1970, contained within the 'Button' letter and map code, and featured in the article 'The 32 Symbol Code-Hidden In Plain Sight'. The Zodiac Killer would again reference the slaying of another police officer - on this occasion Sgt Richard P. Radetich (25), who on June 19th at 5:25 am was gunned down by three shots from a .38 caliber revolver at point blank range through the driver side window of his vehicle, while in the process of serving a parking ticket. He was sat in his police car near 643 Waller Street, The same Waller Street as Park Police Station. The proximity of these three consecutive communications to the area of San Francisco shown below, certainly shows us where the Zodiac Killer's focus was between April 20th and June 26th 1970. However, he wasn't finished just yet. The 'Little List' letter mailed on July 26th 1970 was the fourth and final piece of the jigsaw.

The Zodiac Killer gave us a map code on June 26th 1970, stating the "map coupled with this code will tell you where the bomb is set". To this day no bomb has been unearthed and the threat was likely an idle one, designed primarily to create fear within the American community. However, the map and code were real, and the answer to both has probably been sitting in plain sight for nearly fifty years. The Zodiac, aware that the 32-Symbol cipher was unable to be broken because it had 29 different characters, gave us all the answers one month later when he mailed the July 26th 1970 Little List letter.

The numerous suggested bomb threats were all mailed to the San Francisco Chronicle, so it was evident that his threats were focused on San Francisco itself - which is why the Mount Diablo map included San Francisco and Vicinity rather than just the area around Mount Diablo. The Little List letter was replete with all the information required to crack his map code. In the Button letter (June 26th 1970) the author gave us the "map coupled with this code will tell you where the bomb is set," and just one month later, clearly told us that the code "concerns Radians & # inches along the radians". Therefore, the code will at least contain the words "radians" and "inches" in the answer. In fact, it tells us exactly where the intended bomb was to be set, within the design of the crosshairs with the bold black circle. With the threats geared towards schoolchildren and police, it is apparent that these were the likely targets. The reference to SFPD=0 being incorporated within the crosshairs, along with an accentuated black, bold circle suggesting a location, should be the biggest clue of all. His intended target was the San Francisco Police Department - the location of which can be found within this bold circle. 

The Zodiac Killer referenced "radians" and "inches" (not parts of radians and inches), so with probably just the use of a ruler back in 1970, the Zodiac Killer would measure his intended target this way. Therefore, if he is one eighth of an inch off in his measurements we can forgive him this textual indiscretion. Fortunately, we have Google maps, so the task is much easier.
With an intended target in San Francisco, there is only one answer possible to the "radians" and "inches" conundrum, and it's governed by geography. 1 radian = 57.3 degrees, 2 radians = 114.6 degrees, 3 radians = 171.9 degrees, 4 radians = 229.2 degrees and 5 radians = 286.5 degrees. This is detailed crudely on the map below.

It is apparent that Zodiac wasn't referring to 5 radians, as a line subtended from Mount Diablo at this angle would pass north of San Francisco. The same applies to 3 radians which runs parallel to San Francisco. Therefore, the answer has to be 4 radians or 229.2 degrees. The lines drawn below are only approximations, so are not pinpoint. 4 radians or 229.2 degrees passes over San Francisco somewhere in the vicinity of the airport - but this isn't the answer. If we add back the magnetic north value of 17 degrees in 1970, it equals 246.2 degrees. After all, Zodiac stated on the map, it was "to be set to Mag.N". How do we know 246.2 degrees is the correct angle to be subtended from Mount Diablo? The answer is simple - Zodiac told us so. Place the crosshairs above over a compass rose. A line subtended from the center of the compass rose passes exactly through the center of the bold black circle. In other words, the bold black circle is positioned at 246.2 degrees around the crosshairs. This is 4 radians + 17 degrees (magnetic north). Now all we have to do is find the inches subtended along the 246.2 degree line. This is even easier.     

The map scale is 6.4 miles to the inch, so the geography of San Francisco is self-constraining.
It is approximately 26.5 miles to the eastern edge of San Francisco from Mount Diablo (using the angle of 246.2 degrees).
4 inches would equal 25.6 miles, therefore, 4 inches subtended from Mount Diablo would land in the sea. Unless the Zodiac Killer had a submarine to bury his bomb, this is not very likely.
It is approximately 34 miles to the western edge of San Francisco from Mount Diablo (using the angle of 246.2 degrees). 
6 inches would equal 38.4 miles and again would land in the sea.

Therefore, the answer has to be five inches along the 4th radian (plus magnetic north of 17 degrees). If this lands over the San Francisco Police Department we are in business. But first, we shall fill in the 32-Symbol code using the words or clue given by the Zodiac Killer in the July 26th 1970 Little List letter. The section below is almost the complete solution to the 32-Symbol code. Note how the Zodiac Killer inserts a hashtag style character between the "&" and "inches", with an arrow pointing between these two pieces of text. He is telling us to insert something here. We know from the above calculation it must be five inches, thereby completing the phrase: "P.S The Mt.Diablo code concerns Radians & 5 inches along the radians".
​

Richard Radetich, the fallen officer, possibly referred to in the Zodiac Killer's Button letter was initially assigned to Ingleside Police Station, before moving to Park Station and eventually to Accident Investigation.

Footnote: What level of understanding the Zodiac Killer had regarding the concept of radians is unknown, but they are a counterclockwise value around the circumference of a circle. He placed his crosshairs over Mount Diablo, to which he added a sort of clock face, replacing the number twelve with a zero, stating it was "to be set to Mag.N". It can be shown that 4 radians and Magnetic North will fall within the bold, black circle he placed on his Little List crosshairs. In addition, it can be shown that traveling 2 radians counterclockwise from True North will again fall within the bold, black circle. The use of the clock face and the directional north marker set at zero, may indicate that Zodiac intended this as his starting point for any calculations. The mere fact that the above measurements, either clockwise or counterclockwise, using whole radians, both fall inside the black circle, would seem to suggest that the 246 degree angle subtended from Mount Diablo over San Francisco is where we should be looking.​ The following article shows where the exact location of the bomb was to be set, on the embankment of the Southern Freeway, just 274 feet from Ingleside Police Station. The Answer to the Mount Diablo Code.