As has been pointed out by many intelligent posters, the Zodiac Killer never actually claimed any crimes that would later be attributed to another criminal, because he was simply too vague when insinuating his attachment to these said crimes. Two notable examples would be the June 19th 1970 murder of Officer Richard Radetich and the October 30th 1966 stabbing of Cheri Jo Bates- the latter of which he only 'suggested' in March of 1971, stating "I do have to give them credit for stumbling across my riverside activity, but they are only finding the easy ones, there are a hell of a lot more down there". 
There is without doubt some interesting connections between the Zodiac and Riverside, in particular, the trinity of consecutive communications from April of 1967, to the three July 31st 1969 letters that began the letter writing campaign by the Zodiac Killer. It is therefore understandable that many observers want to interpret the symbol at the foot of the Bates letters as an alphabetical Z, to bridge the connection between the Bay Area and Riverside, and bolster an argument for it. However, was this symbol seriously considered to be an alphabetical Z before the arrival of Zodiac just over two years later, or was it just a convenient reappraisal.   

Here are the two prominent Z like characters from the foot of the Bates letters, mailed to the Riverside Press Enterprise and Riverside Police Department. It is easy to want these to be an alphabetical Z, but unless the Zodiac performed a near identical error on two occasions, or just happened to have aligned his writing paper over an uneven writing surface in both instances, then there is little reason to believe these two characters are a Z.
Additionally, if these two characters were a Z (representing Zodiac), then why not just write 'Zodiac' at the foot of the Bates letters.   
Two years later, on July 31st 1969, the killer we now know as Zodiac announced himself to the world, when he wrote to the San Francisco Chronicle, San Francisco Examiner and Vallejo Times-Herald newspapers, but yet again, despite supposedly masquerading as the Zodiac Killer, he was still apparently reticent to reveal his pseudonym to the world, only introducing himself as "the murderer of the 2 teenagers last Christmass at Lake Herman + the girl on the 4th of July." For a egotistical murderer so bold, he seemed rather reluctant to reveal his identity. Had Vallejo Police Chief Jack E Stiltz not questioned the July 31st 1969 letter writer in the August 3rd 1969 San Francisco Examiner, stating he was "still not convinced the letters and codes were written by the actual killer, and urging the writer to send more letters, with more facts to prove his connections to the crimes," then the August 4th 1969 'Debut of Zodiac' letter would not have been written by the killer. In other words, the 'Zodiac Killer' would still not have been born. How can we reconcile this reluctance to announce the pseudonym 'Zodiac' to the world, with the fact he had supposedly concocted this pseudonym by the time of the Bates letters in April 1967.             

Many people have stated that the Zodiac Killer acquired the pseudonym 'Zodiac' and the crosshairs symbol from the Swiss watchmaker, as they appear together under one banner.
"In 1882, Ariste Calame founded a workshop for the production of special watches in Le Locle, Switzerland. The original name of the company was Ariste Calame and would later become Zodiac. The name "Zodiac" was used early but was not registered until 1908. The founder's son, Louis Ariste Calame, was sent to watchmaking school, and then began to participate in the business in 1895, and took over the business that year." Wikipedia.
If the Zodiac Killer was inspired by a watchmaker, then one has to ask the question- why did he only use the crosshairs in his three July 31st 1969 letters and seemingly abandon the name Zodiac, if an advertisement such as the one on the right was the trigger. Again, he only introduced himself as the Zodiac Killer four days later when the 'Debut of Zodiac' letter arrived at the San Francisco Examiner, and even that wouldn't have arrived if the killer had not been prompted by Vallejo Police Chief Jack E Stiltz..
The idea of gunsight crosshairs proposed by many, may be the likely inspiration for the murderer of three young people at Lake Herman Road and Blue Rock Springs Park. The standalone crosshairs at the foot of each of the July 31st 1969 letters appear to be the logical conclusion to the threat that preceded it.
The San Francisco Chronicle, for example, finished with an ominous threat: "I will go on a kill ram-Page Fry. night. I will cruse around all weekend killing lone people in the night then move on to kill again, until I end up with a dozen people over the weekend." So it isn't particularly illogical that this threat may be followed by a "target" sign or the crosshairs of a gun, without the need for the pseudonym Zodiac or a connection to a famous watchmaker. The killer is simply signing off his letters by indicating he has more people in his sights.
If there ever was the perfect opportunity to announce himself to the American people under the name Zodiac, this was the perfect time- in accompaniment with a trinity of letters and his opening coded message, in which he actually promised to reveal his identity. However, this opportunity was spurned. The reason for this, one could argue, was the pseudonym Zodiac had not been conceived by the killer at this juncture.
The San Francisco Sunday Examiner and Chronicle of August 3rd 1969 opened with the lines "A self-accused killer failed to keep a threat of mass murder here, but there was no slackening of tension or mystery caused by the warning. The police department telephone system was clogged at times by anxious callers asking if the "cipher killer" had been caught."  In this short snippet of text probably lay the inspiration behind the pseudonym Zodiac- as he was not prepared to be labelled the "cipher killer" by anybody. This was the push he needed. The following day the Zodiac was etched into the minds of police and newspapers alike, and has remained so for nearly half a century.    

The answer to the origin of the pseudonym Zodiac likely sits within the pages of the San Francisco Sunday Examiner and Chronicle of August 3rd 1969. 
Somebody with access to newspaper archives may be able to discover the inspiration behind America's most infamous serial killer.
One possibility could be the Zodiac horoscope section, or an advertisement such as the one above for Zodiac watches. Had the latter been the case, it could be strongly argued that the Zodiac Killer was extremely fortunate in signing off his three July 31st 1969 letters with  threatening crosshairs, only to discover they were also the symbol used by the Swiss watchmaker only three days later.
On the contrary, had the Swiss watchmaker been the original inspiration behind the Zodiac's pseudonym and logo, then why did he fail to introduce the name "Zodiac" in his July 31st 1969 letters. He delayed the introduction until his August 4th 1969 letter to the San Francisco Examiner, in direct response to the San Francisco Sunday Examiner and Chronicle article of August 3rd 1969. Therefore, this newspaper had to be the driver behind the name Zodiac, not only because of his lack of affection for the "cipher killer" pseudonym, but because the name Zodiac probably lay somewhere within its folded pages.       

In 2013 Tahoe27 made an excellent discovery, possibly linking the 'Halloween' card with a Tim Holt comic featuring the 'Wheel of Fortune' or 'Rota Fortunae.' The cover displayed the four methods of death used by Zodiac on his 'Halloween' card configuration, that of 'Death By Gun', 'Death By Knife', 'Death By Fire' and 'Death By Rope'. However, the discovery may be far greater than first considered, with the 1952 Tim Holt comic the source behind the design of the 340 cipher, rather than the Halloween card. The 'Halloween' card was just the confirmation that the 340 was not a cipher at all, hence the crossed "sorry no cipher" addition on the inside of the envelope, linking the Paradice and Slaves configuration back to the November 8th 1969 offering.
​See 'Zodiac admitted 340 not a real cipher' [pt1].' 
The Zodiac Killer may have been pushing us in the right direction on October 27th 1970, but his attempt at revealing the workings of the 340 cipher may have begun far earlier, on December 16th 1969- just 38 days after his 'so called' masterpiece, claiming a potential 38 more victims.
The 'Fairfield' letter has been considered dubious Zodiac correspondence, however, it may have been Zodiac's first foray into revealing the mechanics of the 340 cipher, albeit using a rudimentary code as a tool. There are two key features of this correspondence possibly linking it to the 'Halloween' card, and more importantly, to the Tim Holt comic. The second we will deal with later, but the first is the rather childish looking or amateurish offering of a code, consisting of only nine characters.
Clearly, the Zodiac must have known that offering just five different symbols in a code of nine is open to many different interpretations, and therefore practically unsolvable. Therefore, one could suggest this wasn't his intention- he was simply teasing us with the mechanics of how the 340 cipher was designed, by using a rudimentary diagram based on the Tim Holt comic- and something he would expand upon nearly a year later.
One can see how he uses the Zodiac symbol around the crosshairs in the 'Fairfield' letter code, implying a uniformity of message, but aligns five symbols as an introduction to this design. This marries perfectly with 'Death By Gun', 'Death By Knife', 'Death By Fire' and 'Death By Rope.' Death is the introduction, following by the methods of death around the crosshairs. This is exactly what he offered us on October 27th 1970, when he placed the methods of death in the four quadrants of the bisecting Paradice and Slaves.  Here is a representation. 

The November 8th and 9th 1969 communications came as one package, and he certainly wasn't go to reveal the workings of the 340 cipher after just one day in the 'Bus Bomb' letter, so the December 16th 1969 (or possibly December 7th 1969) 'Fairfield' communication was effectively the Zodiac Killer's first communication after the 340 cipher. Can we again call it coincidence that, not only did the Fairfield offering give us a further code, but 'Death By Gun', 'Death By Knife', 'Death By Fire' and 'Death By Rope' would fall readily into its design, as would the 'Halloween' card configuration of Paradice and Slaves so readily mirror the 340 cipher- possibly bringing these three communications in line with one another. The second interesting feature of the Fairfield letter is the wording the author uses:
"This is the Zodiac speaking. I just want to tell you this state is in trouble. I will go for the Goverment life, so don't foreget me. I will kill more people than you cops can count, so look for more blood. You better print."     

The 'Halloween' card has become synonymous with either a threat of a fourteenth victim or the claim of a fourteenth victim, however, the number four may hold more significance within its design. The eyes are obviously of great importance to the Zodiac Killer- after all, he added twelve to the card inner, along with 4-TEEN and the unusual symbol.
He deliberately chose to separate fourteen, creating the number 4. He added four larger eyes outside of the tree, as well as placing four dots around the symbol. He also highlighted four eyes in red on the card outer and inner. 
The strange symbol (with the four dots) could be a joined Z, V and F, and being preceded by four eyes, could simply be interpreted as "look for Zodiac victim fourteen" or with respect to 4-TEEN, "look for number fourteen." 
Up to this point and beyond, none of Zodiac's confirmed or insinuated victims (Kathleen Johns, Cheri Jo Bates and Richard Radetich) lay undiscovered, so it is entirely plausible this card was referring to the disappearance of Donna Ann Lass 51 days earlier. The skeletons indicative of a body lain undiscovered for a measurable period of time.
The coloring of the four skeleton eyes may be suggestive of blood or death, a formula used in the creation of the '13 Hole' postcard on October 5th 1970, where the author added a pasted red crucifix to the card.
The 'Halloween' card could be telling us to "look for Zodiac victim fourteen" or equally "look for blood," as did the Fairfield letter on December 16th 1969, when the author stated "I will kill more people than you cops can count, so look for more blood. You better print."
This discovery by Tahoe27 on December 30th 2013 was certainly a great find, but it may just turn out to be the greatest find of them all. A discovery that may finally reveal the 340 offering to be masquerading as a fully fledged cipher, and as such, has had us chasing our tails for nearly half a century. Albeit, undecipherable at the time, the answer was probably staring us in the face just 38 days after the November 8th 1969 communication- in a letter many thought was penned by a hoaxer.

Courtesy of Zodiac Killer Site forum. These envelopes have been cleaned up using editing tools. 

This is a continuation from the previous article 'Zodiac Admitted 340 Not a Real Cipher.'
You will notice that the paradice and slaves configuration from the 'Halloween' card fits nicely into the 340 cipher.
The two dashes on the 10th line are represented by the letter S.
The left-facing V on the 9th column and 10th line are represented by the letter E.
​The two addition signs on the 9th column are represented by the letter A.
When the letter R of paradice is placed into its only conceivable position, along with the L and V from slaves, it is reminiscent of the 'Halloween' card. What are the chances that this could be achieved accidentally?  

The word paradice travels vertically 17 lines, exactly matching the 17 columns that slaves travels horizontally.The Zodiac Killer placed crosshairs beneath the 9th column, the midsection of the cipher (shown here).
The intersection on the 'Halloween' card configuration forms RAD and LAV, exactly the same as the bisecting center point of the 340 cipher. The Zodiac Killer also underlined the LAV of Paul Averly on the Halloween card envelope, on which he also placed the intersecting "sorry no cipher" on the envelope inner. 
The 'Halloween' card stamp depicts the surface of the moon with a half-earth in the distance and the words "In the beginning God." This phrase fits perfectly on the 1st line (the beginning) of the 340 cipher, with the 15th, 16th and 17th characters uncannily similar to the word GOD (the O in half phase just like the image on the stamp). 

Many have questioned whether the 340 cipher was a genuine offering by the Zodiac Killer, designed to reveal a complete message similar to the 408 cipher- and did the Zodiac Killer hide the key to the 340 cipher in one of his other communications? The answer to the last question is almost certainly yes, but the answer to the first question is almost certainly no. The Zodiac Killer actually admitted in one of his correspondences that the 340 code was not a cipher. 
One of the best finds in recent years was by Tahoe27, a regular contributor to the Zodiac Killer Site forum, who discovered a connection between a Tim Holt comic and the 'Halloween' card. Many features on the cover of the comic parallel the 'Halloween' card, including the wording By Fire, By Gun, By Rope and By Knife, along with "Redmask" (the skeleton eyes) and "Lady Doom" (peek-a-boo you are doomed). However, I believe Tahoe27 is not convinced that the 'Halloween' card was authored by the Zodiac Killer. 
If the 'Halloween' card was authored by an impostor, who based the 'Halloween' card on the Tim Holt comic, then are we to believe he was extremely fortunate that a year earlier, the real Zodiac Killer just happened to create a 340 cipher containing the word "BY" in all four corners of the cipher, along with PARADICE and SLAVES being a possibility, running down and across the cipher on the midpoint vertically and horizontally, just like the configuration on the 'Halloween' card.
Admittedly, the words paradice and slaves have not been proven to exist in the 340 cipher, but the fact they are a distinct possibility by comparison to the 'Halloween' card appears another very fortunate stroke of luck- particularly if we believe the author of the 'Halloween' card wasn't the Zodiac Killer- and only considered the Tim Holt comic in his design of the 'Halloween' card. If the 'Halloween' card was crafted by the Zodiac Killer using only the Tim Holt comic, then the above still applies.
The more likely conclusion we could draw from this, is that the 340 cipher was designed with the Tim Holt comic in mind, and the 'Halloween' card (one year later) was giving us a clue.    

On the right, we can see how the four words "BY" fit into each quadrant of the 340 cipher just like the 'Halloween' card offering. What are the odds that in each quadrant of 80 characters we would find the letters B and Y together either horizontally or vertically every time. Not to mention the fortunate appearance of paradice and slaves bisecting the cipher perfectly. The killer may even have given us his signature in the bottom right corner, along with the running total, which was seven and counting on November 8th 1969.
If this wasn't the intended design of the 340 cipher, then either the Zodiac Killer or an impostor got extremely lucky, in just happening upon a Tim Holt comic that mirrored the 340 cipher unintentionally. But we may just be able to prove a definite link between these two communications and confidently state that both were designed by the Zodiac Killer, and with a fair degree of confidence, argue that the 340 cipher is not a cipher in the true sense of the word. The majority of the characters likely filler, but in this instance, far more than the 18 characters at the foot of the 408 cipher. The reason we may be able to contend the 340 cipher is not a continuous and uniform message like the 408 cipher (and not a cipher as we believe one to be), is because the Zodiac Killer lined us up for a fall and then admitted to it a year later.
On the 'Dripping Pen' card accompanying the 340 cipher, the killer stated
"This is the Zodiac speaking. I though you would nead a good laugh before you hear the bad news. You won't get the news for a while yet. Could you print this new cipher in your frunt page? I get aufully lonely when I am ignored, so lonely I could do my Thing." Was that bad news to come on October 27th 1970, when he mailed the 'Halloween' card.
If we believe that the 'Halloween' card design is referring back to the 340 cipher, then the message concealed on the envelope inner of "sorry no cipher," is the Zodiac Killer finally admitting that the 340 cipher is not the real cipher we had thought.
He is declaring that the 340 is "no cipher," and is in fact, based upon the paradice and slaves configuration. This is why he crosses the phrase "sorry no cipher" to mimic the design of paradice and slaves, using 13 letters in both instances.
The Zodiac Killer could easily have written "sorry no cipher" just the once, but deliberately fashioned it to form a link between the 'Halloween' card design and the 340 cipher.
After searching for solutions to the 340 cipher for nearly half a century, the Zodiac Killer may have given us the answer to its design after just one year, but it was overlooked. We have took the phrase "sorry no cipher" as an apology, that he wasn't giving us a cipher in the 'Halloween' card, when in actual fact, he was apologizing for stringing us along for the best part of a year, and offered us the real solution to the 340 cipher on October 27th 1970, contained within the 'Halloween' card. You could say it was a "trick" and "treat" befitting of Halloween. 
However, there is still a little more to find regarding the methods of death and how they configure within the 340 itself- so the search is not over yet.
ZODIAC ADMITTED 340 NOT A REAL CIPHER [PT2]

​Cipher Explorer tool below, courtesy of Zodiac Killer Ciphers. 

The Zodiac Killer did not mail the three July 31st 1969 letters to the San Francisco Examiner, San Francisco Chronicle and Vallejo Times-Herald, although the murderer of Betty Lou Jensen, David Faraday and Darlene Ferrin certainly did. 
In the letter to the Chronicle, the author suggested that within the code he had mailed we would discover his identity.
He wrote "Here is part of a cipher the other 2 parts of this cipher are being mailed to the editors of the Vallejo Times and SF Examiner. I want you to print this cipher on the front page of your paper. In this cipher is my idenity. If you do not print this cipher by the afternoon of Fry.1st of Aug 69, I will go on a kill ram-Page Fry. night. I will cruse around all weekend killing lone people in the night then move on to kill again, until I end up with a dozen people over the weekend." 
When the cipher was decoded a matter of days later, the code revealed "I like killing people because it is so much fun it is more fun than killing wild game in the forrest because man is the most dangerous animal of all to kill something gives me the most thrilling experence it is even better than getting your rocks off with a girl 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. I will not give you my name because you will try to slow down or stop my collecting of slaves for my afterlife." 
The killer of three assured us that his identity was concealed within the cipher, while all along, knowing the enciphered text would reveal that he was unprepared to give us his name. He was effectively equating his identity with his name, not with his pseudonym or other covert means of identifying him. That is probably because the assailant at Lake Herman Road and Blue Rock Springs was technically not the Zodiac Killer. The "Zodiac Killer" 'only' killed two people under the Zodiac pseudonym, that of Cecelia Shepard and Paul Stine.
As covered in a previous article 'Born on August 3rd,' it was argued that the killer had no "identity" or pseudonym to reveal to us before August 3rd 1969, because he hadn't yet assigned one to himself. Being called the 'code killer' or 'cipher killer' in the newspapers clearly didn't sit well with an ego-driven murderer. He had to give himself a pseudonym worthy of his perceived stature- hence, the "Zodiac Killer" was born. 

​The San Francisco Sunday Examiner and Chronicle of August 3rd 1969 opened with the lines "A self-accused killer failed to keep a threat of mass murder here, but there was no slackening of tension or mystery caused by the warning. The police department telephone system was clogged at times by anxious callers asking if the "cipher killer" had been caught."  The next day the killer would waste no time in introducing us to his new identity or pseudonym, opening with the line "This is the Zodiac Speaking." In other words, looking for his identity in the 408 cipher, in either the enciphered or decoded version would be a futile exercise, because he certainly wasn't going to reveal his real name, and it is extremely likely he had no identity or pseudonym at this juncture. Had he already attributed himself the pseudonym "Zodiac" prior to the July 31st 1969 letters, then this threefold barrage was the perfect time to announce the menacing "Zodiac" to the world, something he clearly failed to do. In fact, he could only muster the unoriginal "This is the murderer of the 2 teenagers last Christmass at Lake Herman + the girl on the 4th of July near the golf course in Vallejo."  
​Four days later however, he would be triggered into action by the lame 'cipher killer' pseudonym designated to him by the public and featured in the San Francisco Sunday Examiner and Chronicle of August 3rd 1969- He was in control, and as such, was not going to be labelled by anybody.
It was now a simple task of replacing one word in his introduction, from "This is the murderer" to "This is the Zodiac." 
This would have significant implications regarding the Riverside murder of Cheri Jo Bates on October 30th 1966, and in particular the three Bates letters. The idea that the symbol on these letters was an alphabetical Z indicating Zodiac would now be nullified, as the Zodiac pseudonym was 827 days in the making. 

Had the murderer opened up with the 340 cipher on July 31st 1969 rather than the 408 cipher, then the statement "in this cipher is my identity" would have had very few detractors, when just four days later a further communication arrived stating "This is the Zodiac Speaking." 
Comparing this introduction to the 'near Zodiac' at the foot of the 340 cipher would have left few in doubt this was deliberately placed, and indeed, he had concealed his identity in the cipher.
However, because the 340 cipher was mailed on November 8th 1969, it is often argued that the 'near Zodiac' may have fell out accidentally on his creation of the cipher- something that would likely never have been argued three months earlier. 
Therefore, if the Zodiac Killer did belatedly give us his identity or pseudonym in the second cipher, when we already knew it, one could suggest it has a secondary purpose, other than to be deciphered in exactly the same way as the other 334 characters.  
There is a growing perception that the 340 cipher is effectively a "bag of puzzles" rather than a continuous uninterrupted message, as many of its features can easily be linked or shown to compare favorably with other correspondences mailed by the Zodiac Killer. This man wasn't a Professor Moriarty style genius- so he either created a method of encryption so illogical, as to make the cipher unsolvable by the logical mind or computer created by logic, he created a mix of puzzles disguised within the cipher, or he created the perfect ghost cipher, to which he would eventually keep his promise by placing his identity within a cipher, but little else. 
Without identifying a key and demonstrating which communication it was found, then the '13 Symbol' and '32 Symbol' ciphers are simply too short to ever be proven as solved. In a previous article we highlighted a piece by Dave Oranchak, in which 46 consecutive alphabetical letters from the historical text of Edward Hyde, Earl of Clarendon, can be placed successfully into a portion of the 408 cipher. Dave Oranchak, the foremost expert on the Zodiac ciphers, commented on this "So, only one piece of text, from a vast collection of eleven billion pieces of text, fit into this chunk of cipher text. A one in eleven billion chance seems to suggest some significance. But don’t be fooled by this. Just because this rare event occurred, doesn’t mean it is anything more than a simple coincidence. If we didn’t already know the real solution to the 408, how do we know that this chunk of old and obscure text isn’t the correct solution?"  
Therefore, one can easily see the multiple solutions that can be harvested from these inadequately designed ciphers. The Zodiac Killer wasn't a genius, but he certainly wasn't a fool either, and must have known that the variability of the '32 Symbol' cipher, and lack of characters within the '13 Symbol' cipher were open to multiple solutions. This was probably part of the fun.
The man, eventually to become known as the Zodiac Killer, mailed the 408 cipher on July 31st 1969. This was a genuine cipher, decoded by Donald Gene and Bettye June Harden of Salinas, California, who both used homophonic substitution to identify the solution. The "cipher killer" or "code killer" would not have lived up to the name given him by the San Francisco Sunday Examiner and Chronicle on August 3rd 1969-  the "killer of codes" would have been far more suitable. 

The following card was postmarked October 17th 1970, but was dated by its author in identical fashion to the '13 Hole' postcard, but on this occasion Oct 12, 1970 (one week later). 
The menacing postcard was directed toward Dr. Edward Adams in Orinda, CA, stating
"The Zodiac is going to change the way of committing murders. I shall announce when I shall commit my murders, The Adamses are Next   you taught me to Mean it.
ADAMS YOU ARE NEXT. ZODIAC."
Whether the '13 Hole' postcard was a genuine Zodiac communication and this was a copycat, both were crafted by the hands of a hoaxer, or both were authentic Zodiac material, is a matter of opinion. 
The Zodiac Killer Site forum has covered this topic extensively, so to read more about this postcard, please visit the link above. Any opinions regarding the 'You are next' and '13 Hole' postcards would be welcome.  
I have cleaned and enhanced the postcard for better viewing (see below).  

Using the Zodiac Killer's own words in the November 9th 1969 'Bus Bomb' letter, we can track his alleged movements that night like a form of global positioning system. After the meeting with Officer Donald Fouke on Jackson Street, he stated
"2 cops pulled a goof abot 3 min after I left the cab. I was walking down the hill to the park when this cop car pulled up + one of them called me over + asked if I saw anyone acting suspicious or strange in the last 5 to 10 min + I said yes there was this man who was runnig by waveing a gun & the cops peeled rubber + went around the corner as I directed them + I disappeared into the park a block + a half away never to be seen again." According to the Zodiac, this placed him entering the park adjacent to Spruce Street (detailed in the October 12th 1969 San Francisco Chronicle article).
Dog units were pressed into the search at this location, again described by Zodiac, apparently hiding in the dense foliage adjacent to Laurel Street, just two blocks east of Julius Khan playground. This is where the story will change from previous articles on this site. 
Had the Zodiac Killer traveled via the safety of the park to reach his vehicle parked somewhere along Pacific Avenue or West Pacific Avenue? He probably hadn't banked on the three teenagers spotting him, or the encounter with Officer Donald Fouke and Eric Zelms, as well as the early response of motorcycles and dog units bearing down on his position. He escaped into the park and by his account, traveled approximately two blocks east to the area of the park opposite Laurel Street: "The dogs never came with in 2 blocks of me + they were to the west + there was only 2 groups of parking about 10 min apart then the motor cicles went by about 150 ft away." This, according to the 'Bus Bomb' letter claims, was his last known location. Was he waiting for an opportune moment to dash out of cover and across the road, to enter his vehicle parked yards away. How do we know his vehicle was parked here? Because this location may have had relevance to the entry on the taxicab trip sheet.

This location, by the intersection of Laurel Street and Pacific Avenue, is the area being described by Zodiac in the letter, when he stated "The dogs never came with in 2 blocks of me + they were to the west." They were congregated by Julius Khan playground. Why though, would a killer park his vehicle four blocks east and two blocks north of the crime scene, greatly increasing the risk of being stopped and questioned. His journey from the crime scene to this location would be 0.4 miles- at least 8 or 9 minutes walking time. This doesn't make a lot of sense. But a murder, at or close to the intersection of Washington and Laurel, would leave just 620 feet to reach his vehicle, parked close to his last known location.
If we marry up the details given by the October 13th 1969 police sketch with his last known location, then his escape route from this intended destination of Washington and Laurel would make far more sense. It is a direct route towards the park.
​   

It has been long believed the Paul Stine taxicab trip sheet gave a destination of Washington and Maple, and for whatever reason Zodiac traveled a block further. Yet, the details on the police sketch clearly state 'Washington and Laurel'.  
Are we to believe the police cannot read the trip sheet correctly and made such a glaring error, or are we to believe the trip sheet actually gave the destination of Washington and Laurel, and the details accompanying the Zodiac sketch are correct.
The taxicab rule book stated that "Drivers of taxicabs and sedans shall keep an accurate waybill specifically setting forth the time of hire and discharge, the number of passengers, the origin and destination and the charges authorized and made for each trip."
Since nobody, including investigators, appear certain of exactly where the taxicab picked up Zodiac, we can probably conclude that Paul Stine didn't write down the origin of the fare- only the destination. 
In the History Channel docudrama 'Hunting the Zodiac,' Lieutenant Tom Bruton, an SFPD homicide investigator, recalled that the destination given in the trip sheet was Washington and Laurel, not Washington and Maple. So, why have we come to believe over the years that the trip sheet stated such a destination.
Keith Power authored an article entitled 'Astrologer Joins Hunt for Killer' in the San Francisco Chronicle on October 17th 1969, just six days after the murder, quoting "When he was picked up by the cab driver about 9.30 pm Saturday at Geary and Mason Streets, Stine noted the destination on his way bill (trip sheet) as Washington and Maple Streets."
How did Keith Power seemingly get hold of this information, to which no one else has been able to ascertain. It appears he may have been told this information by somebody connected to law enforcement, or just assumed the trip sheet noted Washington and Maple.
Somebody, using the taxicab meter reading at 10.46 pm, backtracked to calculate the origin of the taxicab, and this, coupled with the statement by Zodiac of "I am the murderer of the taxi driver over by Washington St and Maple St last night," may be the reason it was concluded that this was Zodiac's intended destination, and what was written on the trip sheet.
Keith Power stated "he was picked up by the cab driver about 9.30 pm Saturday at Geary and Mason Streets", despite the fact this has not been definitively proven. If this isn't fact, then we can argue, neither is the Washington and Maple destination. If Keith Power had seen the trip sheet and it stated Mason and Geary, why have police been attempting to discover the origin of the taxicab journey down the years. Furthermore, and one must reiterate this fact- why would the Zodiac Killer travel to either Washington and Maple or Washington and Cherry, many blocks away from his final claimed location, two blocks east of Julius Khan playground. This fact alone, must shed doubt on whether the trip sheet ever read Washington and Maple, and the Zodiac Killer at the last minute changed his plans to travel one block further. If this were true, its never been made public.
However, this still doesn't answer the question of why a killer who intended to murder a taxicab driver by Washington and Laurel, ended up four blocks west of his original destination. 
Officers Donald Fouke and Armond Pelissetti (and probably more police) were patrolling the Richmond District area the night of October 11th 1969. Donald Fouke stated in the 2007 Zodiac documentary "My regular partner was off. I don't recall the reason why he was not working that night. However, Eric Zelms was assigned as my partner that night. We were patrolling the eastern side of the Richmond district, going northbound on Presidio Avenue. We had passed Washington Street when a broadcast came in of a shooting at Cherry and Washington Street."
Could it be as simple as Zodiac, who was determined to follow through on murder that night, was approaching the intersection of Washington and Laurel in the taxicab of Paul Stine, when he saw a police vehicle in the vicinity, and decided to travel several blocks further in order to reach a safe distance or buffer zone to commit his murderous plan. 
This would ultimately leave him detached from his vehicle, necessitating the need to backtrack along Jackson Street, past Donald Fouke's approaching police vehicle and toward Laurel Street. The taxicab traveled four blocks east past Laurel Street, and Zodiac walked back four blocks west to Laurel Street. In effect, a complete waste of time. This lends credence to a Zodiac Killer, whose initial intended destination was the intersection of Washington and Laurel, corroborated by the 'Wanted Poster' and Lieutenant Tom Bruton of the San Francisco Police Department.
"There was only 2 groups of parking about 10 min apart then the motor cicles went by about 150 ft away going from south to north west."  
"The car drivers should have just parked their cars and sat there quietly waiting for me to come out of cover."
But they didn't, and Zodiac was away into the night.           

The first part of this article has been copied from a previous offering, however, I have added some extra material to the foot of the article. ​
The following will be explaining in more detail the subconscious wording of the Zodiac Killer in his first three communications with the Bay Area newspapers, putting forward a compelling argument that the confirmed murderer of five was a resident of the Vallejo area. The Zodiac Killer would never willingly have given us his name or the locality of his residence, however, one could argue that had he revealed his home location without realizing it, then it is likely true. To do this, we have to examine closely the wording he chose on his July 31st 1969 letters using the present and past tense. Here is what the Zodiac stated on each communication:
Vallejo Times-Herald: "Here is a cyipher or that is part of one. the other 2 parts have been mailed to the S.F. Examiner + the S.F. Chronicle."
San Francisco Examiner: "Here is a cipher or that is part of one. The other 2 parts are being mailed to the Vallejo Times + S.F. Chronicle." 
San Francisco Chronicle: "Here is part of a cipher the other 2 parts of this cipher are being mailed to the editors of the Vallejo Times and SF Examiner." 

You will notice the two San Francisco newspapers are being addressed in the present tense regarding the other two mailings, using the word ARE. While the Vallejo Times-Herald newspaper is being addressed in the past tense regarding the other two mailings, using the word HAVE. There is every indication that this has been written subconsciously by the Zodiac Killer and therefore he has inadvertently given us his home location of Vallejo. The word "are" immediately precedes Vallejo Times on both occasions. 

​If the Zodiac Killer lived in Vallejo when he composed these three communications, he would associate Vallejo with the present (everything that is happening in or around him). If the Zodiac Killer had traveled to San Francisco for a day out and then had returned to Vallejo, he would be referring to San Francisco in the past tense: "I have been to San Francisco and have mailed three letters." In the Vallejo Times-Herald communication text above, he is doing just that, when referring to his mailing of letters to the Chronicle and Examiner, which are approximately 40 miles away: "the other 2 parts have been mailed to the S.F. Examiner + the S.F. Chronicle."  Because now he is back home. ​

​When he is at home in Vallejo writing these communications, his mind is actually projecting forward to their future postings in San Francisco, which is where they were ultimately mailed. 
In two of the communications to the Chronicle and Examiner in San Francisco, he is referring back to his hometown Vallejo in conjunction with another mailing. Therefore he uses the plural form of the present tense, in the word "are". That is because at this moment in time (the time of writing), he is present here in Vallejo, so is effectively forced to abandon the past tense of"have". The Zodiac Killer cannot refer to Vallejo in the past tense in this instance, because the Vallejo Times-Herald office is in his locality, and therefore he is referring to it in the present of "are". 
Anything in the Zodiac Killer's locality is the 'here and now.'  Anyplace one has to travel and return, whether in the mind or reality, will be referred to in the past tense. Traveling to San Francisco physically and returning to Vallejo will now be referred to as "I have mailed", because of the distance you associate with the offices of the San Francisco Chronicle and San Francisco Examiner from Vallejo. Even if you do it in your mind.
But the Vallejo Times-Herald office is effectively on your doorstep and will therefore be seen as in the "here and now" to somebody living in Vallejo, without any real distance associated with it. Therefore it doesn't need to be referred to in the past tense, which is exactly what Zodiac does in two of his communications regarding the mailing to Vallejo- he uses the word "are". 

​The Zodiac Killer is associating the Vallejo Times-Herald as his home location, so let us use this analogy with a fictitious friend.
Zodiac is in his house opposite the Vallejo Times-Herald office and he has just finished preparing his three July 31st 1969 letters for delivery. He bids farewell to his housemate and travels to San Francisco to post his letters. Upon his return two hours later he says to his friend "I have posted two letters to the San Francisco newspapers".  Looking out of his window and pointing he states "One letter is being posted to the Vallejo Times-Herald." He would be using the present tense regarding something in the "here and now". But because he is referring to the Vallejo Times-Herald mailing in two communications he uses the present tense "are". It clearly indicates that on a subconscious level the Zodiac Killer is referring to Vallejo in the present tense, because that is where he was when he penned the three July 31st 1969 letters.

The old Vallejo Times-Herald office was at 440 Curtola Parkway, just 0.96 miles (as the crow flies) from the Springs and Tuolumne payphone.

To know that Lake Herman Road and Blue Rock Springs were frequented by courting couples, the Zodiac would have required  either first-hand knowledge of traveling that route regularly, such as commuting to work or visiting friends or family, or acquired the knowledge through a third party. Knowing this was a target rich area may have suggested that he lived locally, and free from work, cruised along Columbus Parkway and Lake Herman Road many times, before ultimately finding any suitable victims from his perspective- victims that would be in the right place at the right time.
Kim Rossmo, a pioneer of geographical profiling, stated "The San Francisco murder differs significantly from the Zodiac's other crimes. Up to this point he was hunting in locations that had a good probability of containing his desired victims. Target selection was a function of area, not of an individual. However, it is unlikely the Zodiac was successful in all his searches; serial killers typically engage in extensive hunting activities, and for every attack there are many unsuccessful search attempts. In San Francisco, however, the Zodiac controlled the situation through his selection of victim type. The need for such control could be indicative of the distance the Zodiac had to travel to the crime site. Criminals who travel longer distances to offend are less likely to use uncertain target selection techniques." 

His familiarity with the Vallejo area and its lovers' lane areas, as opposed to San Francisco, may also have inadvertently leaked from the pen of Zodiac, when only using the word "couples" in relation to the letter mailed to the Vallejo Times-Herald,  Only one confirmed person was murdered in San Francisco by the Zodiac Killer, and Paul Stine was a lone person driving his taxicab at night. We know of no couples he targeted or claimed to have targeted in this area.
​Vallejo Times-Herald: "I will cruse around and pick of all stray people or coupples that are alone then move on to kill some more untill I have killed over a dozen people."
​San Francisco Examiner: "I will go on a kill rampage Fry night. This will last the whole weekend, I will cruse around killing people who are alone at night untill Sun Night or un till I kill a dozen people."
San Francisco Chronicle: "I will go on a kill ram-Page Fry. night. I will cruse around all weekend killing lone people in the night then move on to kill again, until I end up with a dozen people over the weekend."​

The Zodiac Killer appeared to place more importance on his Vallejo Times-Herald correspondence reaching its destination quicker, by affixing four 6 cent Roosevelt stamps (24 cents postage) in total, as opposed to the San Francisco letters in which he used only two stamps on each. 
Did the Zodiac Killer employ this tactic to suggest to police he was a Vallejo resident, or was he eager to ensure he could read his offering to his hometown paper in Friday's edition, sitting in his favorite armchair. 
The cipher was mailed in three parts, with the Vallejo Times-Herald correspondence holding part one of the cipher message. Did this again show his possible home location of Vallejo, subconsciously beginning his message from where he was authoring it from.

Without a DNA or fingerprint connection apparently linking Riverside and the Zodiac Killer, many have tried to link the two through his correspondence. Was the Zodiac Killer responsible for the murder of Cheri Jo Bates in Riverside on October 30th 1966, and if so, was he a well-read individual with connections to the campus library.
David Oranchak of ZodiacKillerCiphers highlighted the text of Edward Hyde, Earl of Clarendon, present in the 408 Cipher, in his article entitled 'Throw the book at him, Part 3'. The section of text is from a book called 'The life of Edward, Earl of Clarendon, lord high chancellor of England: Volume 2':
​Forty-six consecutive letters from this text corresponds with a section of the 408 cipher. Dave Oranchak, the foremost expert on the Zodiac ciphers, commented on this "So, only one piece of text, from a vast collection of eleven billion pieces of text, fit into this chunk of cipher text. A one in eleven billion chance seems to suggest some significance. But don’t be fooled by this. Just because this rare event occurred, doesn’t mean it is anything more than a simple coincidence. If we didn’t already know the real solution to the 408, how do we know that this chunk of old and obscure text isn’t the correct solution?"  
I wanted to validate or refute whether this was a simple coincidence or not by examining whether the works of Edward, Earl of Clarendon featured anywhere else in Zodiac or Riverside correspondence. One wouldn't envisage many American criminals using the writings of a seventeenth century English statesman to form part of their serial murder exploits, and certainly not without access to a comprehensive library of books.
This is when I noticed another piece of obscure text from Edward, Earl of Clarendon and flew back to the last piece of notable text from the presumed Zodiac Killer on the Riverside desktop- the title of which was "sick of living/unwilling to die."  
One of Edward Hyde's quotes was “They who are most weary of life, and yet are most unwilling to die, are such who have lived to no purpose, — who have rather breathed than lived.” http://izquotes.com/quote/385232.
​Although not perfect, I couldn't help wondering if the Zodiac Killer was recalling from memory, as he did with 'The Mikado.'
Had he plagiarized "weary of life, unwilling to die" to "sick of living, unwilling to die," and would then later hide another section of Edward Hyde's text in the 408 cipher, as a form of link between the murder in Riverside and the Bay Area.
Edward Hyde, Earl of Clarendon was also an avid user of ciphers as revealed here in literary manuscripts; 
"Naturally a substantial portion of Clarendon's surviving manuscripts comprises his personal correspondence — both letters received by him from numerous correspondents and his own letters, written or signed by him, whether drafts, retained copies, or the letters actually sent. Among many notable examples are his letters written in August 1646 to William, Lord Widdrington, and to Sir John Berkeley, announcing the beginnings of his History of the Rebellion, and the letter he wrote on 12 November 1646, to Sir Edward Nicholas, describing his plan for the work and stating that he had already completed sixty sheets of it. Some of his letters, particularly those dating from the Civil War period, are wholly or partly in cipher or make use of pseudonyms in both salutations and signatures. The codes to sixteen such ciphers used by the Royalists are written out in Bodleian, MS Clarendon 94, and see also British Library,"
However, are there any alternatives to Edward Hyde- someone that possibly connects the 'Confession' letter and Riverside 'Desktop Poem' together, using the title of each communication.   

I have always believed the Zodiac Killer was driven by some form of warped religion- one that drove him to the confession box after each crime and manifested in the form of letters mailed to the newspapers and police.
Using the Riverside library as our primary focus once again, did the works of an early Christian theologian and philosopher influence the writings of Zodiac. 
'Peter A Fiore concludes that John Milton (an English poet, author of Paradise Lost, polemicist, man of letters, and civil servant for the Commonwealth of England) like many humanists, Christian philosophers, Reformers, and theologians of every variety in the early seventeenth century, drew widely from Augustine and that such indebtedness gave a richer and fuller theological dimension to his epic of lost paradise and enhanced the meaning of the poem.' 
link  
The Augustine he is referring to is St Augustine of Hippo (13 November 354 - 28 August 430), a Roman African, Christian theologian, whose writings influenced the development of Western Christianity and Western Philosophy. 
His work was translated by many individuals, but here are a few examples:
1] "Now is not the time for asking questions but for confessing to You. I was wretched, just as every mortal soul is wretched who is bound to the friendship of mortals. We are torn to pieces when we lose them, and so become aware of how wretched we were, even before we lost them. This is the way it was with me. I wept bitterly, and found rest only by weeping. I was so wretched that I held that life of wretchedness to be more dear to me than the friend for whom I wept. Even though I wanted to change it, I was more unwilling to lose it than I had been to lose my friend. Actually, I doubt that I would be willing to lose it even for him, as it is said of Orestes and Pylades, if that is true, that they would have gladly died for each other, or both died at the same time, rather than living part from each other. But I had begun to be afflicted with a strange kind of feeling, different from theirs. I cannot explain it, but I was tired of living and yet, I was afraid to die." link.​

2] "I do not know whether I would have been willing to die for him in the way that Orestes and Pylades, if the story is true, were willing to die together for each other. And yet a strange feeling had grown in me, and it was very different from theirs; I was sick and tired of living but I was too afraid to die." link.
​3] "But in me there was an odd kind of feeling, the exact opposite of theirs, for I was at once utterly weary of life and in great fear of death." link.
4] "I was at the same time thoroughly tired of living and extremely frightened of dying.”
link.
Was this a case of the Zodiac Killer recalling the literary work of another, as he did with the Gilbert and Sullivan Mikado, but paraphrasing it. However, in this instance, the author chose sick of living/unwilling to die as his title of the 'Desktop Poem'. 
On its own, this connection could appear a little unconvincing, but the author of the Riverside 'Desktop Poem' may have mailed correspondence to the Riverside Homicide Detail and Riverside Press Enterprise on November 29th 1966, in the form of letters entitled 'The Confession.'
Two weeks after the October 30th 1966 murder of Cheri Jo Bates, the Riverside Police staged a library reconstruction of the crime on November 13th 1966. The probable murderer then mailed the 'Confession' letters. St Augustine of Hippo wrote the Confessions (in which the above examples of text are contained), an autobiographical piece of work consisting of 13 books. "The Confessions of Saint Augustine in order to distinguish the book from other books with similar titles. Its original title was Confessions in Thirteen Books, and it was composed to be read out loud with each book being a complete unit.
Confessions is generally considered one of Augustine's most important texts. It is widely seen as the first Western autobiography ever written, and was an influential model for Christian writers throughout the Middle Ages. Professor Henry Chadwick wrote that Confessions will "always rank among the great masterpieces of western literature." link.  
St Augustine of Hippo was born on November 13th, the exact date of the library reconstruction. 
"The City of God Against the Pagans (Latin: De civitate Dei contra paganos), often called The City of God, is a book of Christian philosophy written in Latin by Augustine of Hippo in the early 5th century AD. The book was in response to allegations that Christianity brought about the decline of Rome and is considered one of Augustine's most important works, standing alongside The Confessions, The Enchiridion, On Christian Doctrine and On the Trinity. As a work of one of the most influential Church Fathers, The City of God is a cornerstone of Western thought, expounding on many profound questions of theology, such as the suffering of the righteous, the existence of evil, the conflict between free will and divine omniscience, and the doctrine of original sin."
"Shortly before Augustine's death, the Vandals, a Germanic tribe that had converted to Arianism, invaded Roman Africa. The Vandals besieged Hippo in the spring of 430, when Augustine entered his final illness. According to Possidius, one of the few miracles attributed to Augustine, the healing of an ill man, took place during the siege. According to Possidius, Augustine spent his final days in prayer and repentance, requesting that the penitential Psalms of David be hung on his walls so that he could read them. He directed that the library of the church in Hippo and all the books therein should be carefully preserved. He died on 28 August 430. Shortly after his death, the Vandals lifted the siege of Hippo, but they returned not long thereafter and burned the city. They destroyed all of it but Augustine's cathedral and library, which they left untouched."  Wikipedia.
​Was the murderer of Cheri Jo Bates somehow connected to the Riverside library, a well-read individual, who subtly introduced sections of text from St Augustine of Hippo into the titles of both the 'Riverside Desktop Poem' and 'The Confession' letter in order to give himself a feeling of superiority over the police and newspapers, as he would ultimately do several years later. 

"SICK OF LIVING, UNWILLING TO DIE" 

In light of the possible capture of the Golden State Killer on April 24th 2018, there has been renewed excitement in recent weeks concerning the possible DNA left by the Zodiac Killer when he mailed his many correspondences. Other sources that may have harbored DNA have been mentioned, such as the car door, bottle and Zodiac bindings at Lake Berryessa, the gloves from Presidio Heights, along with potential blood from the killer deposited on the clothing of Cheri Jo Bates at Riverside on October 30th 1966. This may or may not be a Zodiac crime, but it is still an avenue that must be pursued. 
Michael Cole, who runs the 'Zodiac Revisited' website, details the mitochondrial DNA findings of 1999, obtained by Michael Morford and pertaining to the case of Cheri Jo Bates. But the hope is now, that a full DNA profile can be obtained and cross checked using genealogy websites and familial DNA linkage. Separating any blood from the killer on Cheri Jo Bates clothing by locating Y-markers has always presented a challenge to forensic investigators in a mixed sample, however, there is a possibility that we may, or could have had the blood of the killer at Riverside from somewhere other than the clothing of Cheri Jo Bates.
"The Y chromosome is currently by far the most popular marker in genetic genealogy that combines genetic data and family history. This popularity is based on its haploid character and its close association with the patrilineage and paternal inherited surname." PubMed.
Riverside Police were meticulous in their evidence gathering, performing a library reconstruction of events the night of the murder and taking fingerprints and hair samples from attendees of the library on Sunday October 30th 1966. They retrieved a hair sample from a blood clot at the base of Cheri Jo Bates' right thumb, recovered a cigarette butt from the alleyway floor and took fingernail scrapings from the victim. They also clearly considered the possibility that the killer of Cheri Jo Bates may have cut himself during the attack with a less than sturdy knife, described by Captain Cross as a pocket knife with a "3-inch blade or less." Even the author of the 'Confession' letter on November 29th 1966 (whether the killer or not) claimed that the knife broke towards the end of the attack. Was this the pivotal moment that ended the callous attack on the defenseless young woman.
The 'Inside Detective' magazine revealed one crucial piece of evidence from the Riverside alleyway crime scene. It stated "The driveway adjacent to 3680 Terracina Street was so churned up it looked like a tractor had been over the ground. The girl, who was very athletic, put up a terrific struggle. At the murder scene, drops of blood leading from the body to Terracina Street indicated to the detectives, that the murderer had walked back to the street following the slaying."
Using an old overhead view of the campus in 1966 (not shown here) and the fact she was positioned between the two vacant properties of 3680 and 3692 Terracina Drive, it is possible to calculate how far Cheri Jo Bates' body lay up the alleyway from Terracina Drive. Below I have placed all the relevant distances.     

Cheri Jo Bates was lying approximately 100 feet southwest of Terracina Drive, shown in relation to the football field and scoreboard in the distance. That is an extensive blood trail leading away from the body, if the interpretation of the police statement is correct. 
​The 'Confession' letter stated "When we were away from the library walking, I said it was about time. She asked me "about time for what". I said it was about time for her to die. I grabbed her around the neck with my hand over her mouth and my other hand with a small knife at her throat. She went very willingly." If the attack began in the vicinity of where her body was discovered, we are left with two possibilities: The blood trail to Terracina Drive was the victim's blood, dripping from the killer, or the killer's blood dripping from a cut hand. The blood trail, if significant enough to be noticed by detectives, was continuous to the sidewalk of Terracina Drive, then it could be argued to be blood secreted from a continuously bleeding hand, as opposed to a killer having blood on his person (absorbed by his clothing) or a small knife. Presumably, the killer would have pocketed the knife in advance of reaching the street. This must have been considered by investigators who visited the crime scene. But, was this blood gathered from the alleyway floor and stored for 'future use'? 
Cheri Jo Bates' blood type detailed at autopsy is rare in the USA population. It was AB RhD positive, which accounts for only 3.4% of the American population. Even with the limited forensic capabilities in 1966, this testing was a simple affair, and could have determined whether the blood trail extending toward Terracina Drive was that of the killer's or from the victim.
The pattern or tail of the blood drops could certainly have determined the direction of the killer within the alleyway. Since detectives concluded that the "drops of blood leading from the body to Terracina Street indicated to the detectives, that the murderer had walked back to the street following the slaying," then it remains a possibility that the killer injured himself during the attack, allowing the trail of blood to extend the full 100 feet in distance, as opposed to the limited blood secretion possible from a small pocket knife or clothing. 
If the murderer of Cheri Jo Bates cut himself when he delivered the stab wound to the young woman's back during the latter part of the attack, there may be limited blood transfer to her clothing, however, there may be have been far more present in the vicinity of the crime scene, during his 100 foot journey to exit the alleyway. By odds alone, it is unlikely the killer had an AB RhD positive blood type, making it easy to determine the origin of the blood on the alleyway floor, and whether it was from Cheri Jo Bates or even the Zodiac Killer himself.