Many theories have been put forward in an attempt to locate the likely home residence of the Zodiac Killer during the period of his four confirmed attacks, presuming of course he had a fixed abode. But if he did, where was it and did he leave any clues to point us in the right direction. This has been tackled many times before under the banner of geographical profiling, but like anything, it relies heavily on a presumption of fixed residence, the killer's working pattern, traveling distances, buffer zones, the least effort principle and such like. Here we will make one preliminary assumption based on the killer's movements directly after the murder and attempted murder of Darlene Ferrin and Michael Mageau at Blue Rock Springs on July 4th 1969, that in all likelihood he headed for the safety of home after the attack and examines a timeline that suggests that San Francisco was an unlikely destination. This does not entirely preclude San Francisco as a possibility for a base location, it just suggests that if he traveled home that morning San Francisco would have seemed an odd choice, bearing in mind what we know of the events that night in the vicinity of the Blue Rock Springs Park.  

After the attack the Zodiac Killer exited Blue Rock Springs parking lot at approximately midnight and made the phone call to Nancy Slover at 12.40 am at the intersection of Springs and Tuolumne. The intervening 40 minutes are unknown. It has been stated many times that we have a missing 30 minutes, as we know the journey time to the payphone is roughly 10 minutes. This however is factually incorrect, as it makes the assumption of redundant time. If the killer for example headed to his Benicia home and returned to the payphone, he had 40 minutes available to him, as he did if he lived en route to the payphone or right beside it. The missing 30 minutes takes a premise that 10 minutes is wasted time.
But the question still remains, he made a phone call 40 minutes after the attack, when it could conceivably have been made as early as 12.10 am. So what was the Zodiac Killer doing during this timeline. Was he disposing his weapon nearby or at home, was he parked up somewhere or just driving aimlessly around in the night.
There are good reasons to believe the killer was a resident of Benicia as the driving time to this location for the safe disposal of the weapon and a turnaround time of 10 minutes, takes us back to the payphone at Springs and Tuolumne at approximately 12.40 am. But if he was a resident of Vallejo, a home location somewhere in the vicinity of the payphone is equally credible, particularly as some have suggested, he walked back to the Springs and Tuolumne intersection as a means of drawing less attention to himself. It has also been noted that prime suspect Arthur Leigh Allen's residence at 32 Fresno Street was only half a mile or as little as 9 minutes walking distance from the payphone. A journey time to Fresno Street from Blue Rock Springs Park is about 10 minutes, the walk to the payphone is 9 minutes, leaving a turnaround time of 21 minutes, had the killer gone straight home to this residence.
But the question remains, if the killer was a resident of San Francisco and headed for home immediately after the Blue Rock Springs attack, where is the logic applied to the missing 40 minutes and the choice of payphone. Are we to assume he drove around randomly in the night or sat in his car for a notable period of time, made the call to Nancy Slover, then departed for San Francisco.

Whatever route you take from Blue Rock Springs Park to San Francisco, there are innumerable opportunities to make a phone call on the journey home and most, if not all, provide a much safer option than placing the call at Springs and Tuolumne. If the killer lived in San Francisco the perfect buffer zone from the murder scene and his residence would be a mid point between the two locations. But based on San Francisco, the received phone call at Springs and Tuolumne appears on the face of it an unnecessary risk. The missing 40 minutes can be explained with Benicia or Vallejo on the understanding that his primary motive was to ditch the weapon before he placed the call. The same cannot be said of San Francisco, despite the reasoned argument that most of the Zodiac Killer's correspondence was mailed from this location, suggesting this was more likely his place of work rather than his doorstep.
Of course it would be presumptuous to exclude San Francisco based on this analysis alone, as there are other possibilities, but if the Zodiac Killer's first thought was to head home after the Blue Rock Springs attack, this choice of payphone has relevance. Had the Zodiac Killer headed across the bay, he would still have had a thirty plus mile journey ahead of him to the safety of home, seemingly in contradiction to traveling west towards the heart of Vallejo, some 40 minutes after the attack and placing a phone call, that inherently could have been made from anywhere. 

** Your opinion is valued and any theories or counter arguments can be placed in the comments section below. 
Here is a website that extensively covers certain aspects of the case in great detail, including the letters and can be accessed via the banner link below.            

An article in the San Francisco Chronicle by Paul Avery dated November 12th 1969 and titled I've Killed Seven, The Zodiac Claims, clearly states "As proof the letters were from the true Zodiac and not an imposter, the mass murderer enclosed another portion of the piece of shirt he tore off the body of San Francisco taxi driver Paul Stine". Then in a second article on December 28th 1969, entitled New Zodiac Letter...Fears He'll Kill Again, it states "A few days after the Stine killing, Zodiac sent a letter to San Francisco newspapers and also included a swatch of Paul Stine's shirt. Another letter and another piece of Stine's shirt was sent to a Newspaper on November 11th". The 340 Cipher and Dripping Pen Card/Bus Bomb Letter were mailed in close succession on November 8th and 9th at the weekend and may have arrived at the beginning of the following week, accounting for the November 11th attribution. Then, in a Youtube documentary commencing at the 3 minute mark, it confirms that a total of three shirt pieces were sent. Two articles and one documentary, all indicating that a third section of Paul Stine's was sent accompanying either the 340 Cipher or Bus Bomb Letter.

Had the Zodiac Killer set aside three portions of shirt to send, it is highly unlikely he would want to be sitting on incriminating evidence for too long - and after the murder of Paul Stine in Presidio Heights on October 11th 1969 he would mail his three portions of shirt with his next three correspondences. His first being the October 13th letter, just two days after the murder, his next letters were postmarked within one day of each other, so he sent the second portion with these, with the final piece being mailed with the Melvin Belli Letter on December 20th 1969. What he didn't do however, was mail a piece of shirt with the Fairfield Letter on December 16th, four days before the Melvin Belli Letter.

It cannot be known for certain, but the Fairfield Letter seems to be suggesting a link to the Lake Berryessa stabbing on September 27th 1969, the only crime committed thus far with a knife. It was always questioned why the Zodiac failed to brag about his theatrical crime on the shoreline of Lake Berryessa, after all, it was his most daring to date. There is no definitive answer, but one thing the Zodiac Killer never foresaw, was that he was to leave a surviving witness, in Bryan Hartnell. He could have bragged endlessly about this crime, but in hindsight his failure to kill both victims actually played right into his hands. The detailed account of Bryan Hartnell, the description of the killer's costume and the extensive newspaper accounts gave him all the publicity he could ever have wished for. What more was there to add.

However, newspaper accounts were starved of the full details, because the 'by knife' attribution on the car door of Bryan Hartnell's car was withheld from the public in an attempt to flush out the real killer from any subsequent hoaxers - and the Fairfield Letter may be one example. Anybody who was aware of the Lake Berryessa attack could have concocted the phrase 'The Bleeding Knife of Zodiac' - and more importantly its failure to highlight 'by knife' was an opportunity missed from a killer now determined to link himself to the authenticity of his correspondence by enclosing the swatches of Paul Stine's shirt.

The Zodiac Killer had his ego dented when his first cipher was cracked in a matter of days by school teacher Donald Gene Harden and his wife, Bettye June Harden, two amateur sleuths. His response was to send us the still unsolved 340 Cipher, crafted either with no solution, or a solution that went far beyond simple homophonic substitution. The Fairfield Letter, however, seemed a retrograde step into mediocrity, when the supposed Zodiac Killer mailed just nine symbols, showing little effort in the apparent guise of a small code and beginning his letter with "I just want to tell you this state is in trouble, I will go for the government life". This appeared more like a politically motivated correspondence, with bold claims of another potential 38 victims. The 'knife' wording does look similar to the writing on the card door at Lake Berryessa, but the template for these letters was freely available throughout his correspondence up to this point. The one thing that is apparent, is his failure to corroborate this letter with a swatch of Paul Stine's shirt, that has led some people to believe the Fairfield Letter was written by the hand of a hoaxer and the real Zodiac Killer was to contact authorities just four days later.   

The Fairfield Letter was mailed on December 16th 1969, sandwiched between the Bus Bomb Letter of November 9th and the Melvin Belli letter on December 20th - and it was this reason, along with its design that has placed this relatively early letter into the section of unlikely Zodiac correspondence. The main reason for this, centers on the belief that the Zodiac Killer after murdering Paul Stine in Presidio Heights on October 11th 1969, actually mailed three pieces of Paul Stine's shirt to the newspapers, not two as is widely believed. This is not a new concept, with a thorough section devoted to this on the excellent ZodiacKillerSite forum here - but for those who have not come across this, we shall do a brief summary.

It is widely acknowledged that two pieces of Paul Stine's shirt were sent - firstly to the San Francisco Chronicle on October 13th 1969, just two days after his murder and secondly on December 20th 1969 to the home residence of prominent attorney Melvin Belli - but a third piece was mailed along with the Bus Bomb Letter on November 9th 1969, outlined in two articles written by the San Francisco Chronicle and mentioned in a Youtube documentary. Anyone can believe in mistakes, but the wording in the Chronicle is specific. Additionally, the mailing of three portions of Paul Stine's shirt makes perfect sense, as shown in photographs of the shirt on the Zodiac Killer Facts website, marked A, B and C. 
Here is an excerpt from the FBI files (Zodiac 5 page 46/249), clearly showing three shirt pieces were mailed.        

The first two crimes of the Zodiac Killer, Lake Herman Road on December 20th 1968 and Blue Rock Springs on July 4th 1969, are considered the most closely aligned of his four attacks, after all the Zodiac Killer did tie them up into one neat bundle when he first contacted the newspapers, firstly with his three cryptograms sent to three newspapers on July 31st 1969 and then in his follow up 'Debut of Zodiac' letter on August 4th 1969, where he mentions both crimes. This may have influenced the observer to fill in the blanks regarding the Lake Herman Road attack, taking preconceptions of the second crime and overlaying them onto the first. This, along with the depiction of events in documentaries and films, has ultimately led us to believe that his third crime at Lake Berryessa was so far removed from his first two crimes, it must be placed under heavy scrutiny as a Zodiac crime, with suggestions of a copycat killer.  A post on Facebook Zodiac Killer 340 by Gregory Haugevik, prompted another look into the Lake Herman Road murders, its comparison to the Blue Rock Springs attack and the widely held belief, that his costume driven attack at Lake Berryessa was separate and unique to his first two crimes.   

Taken from Facebook: "We are so reliant on the testimony of James Owen. Since this crime was so close to the Blue Rock Springs attack, I try to look for comparisons to see if they are connected. In both instances it was a lone couple in a deserted area, both in the last hour of the night, 9 shots were fired at both crime scenes, with handguns and on both occasions his first port of call was the passenger side of the vehicle, not the driver side. But one thing has always confused me about the Lake Herman Road crime: why did he try and force the couple out of the Rambler, why didn't he just approach the passenger side and start firing immediately, without warning, as he did at Blue Rock Springs. What purpose did he have for extricating David Faraday and Betty Lou Jensen from the car, after all, if this were his first crime, he should have been less confident. Whatever his reasons, I believe since David Faraday's class ring appeared dislodged from his finger and he supposedly had a swelling on his jawline, he may have got into an altercation with the Zodiac, before he was shot. Even after coaxing the couple from the car, there was never any need to shoot David Faraday from such close contact range, it is unnecessary and risky, unless of course things never went to plan. This may possibly have influenced his actions at Blue Rock Springs, when he decided not to risk losing control of the situation once again, so shot the couple immediately, while they were entrapped within their vehicle. This is what he said in the 'Debut of Zodiac' letter " Last Christmass In that epasode the police were wondering how I could shoot + hit my victims in the dark. They did not openly state this, but implied this by saying it was a well lit night + I could see silowets on the horizon. Bullshit that area is srounded by high hills + trees. What I did was tape a small pencel flash light to the barrel of my gun. If you notice, in the center of the beam of light if you aim it at a wall or ceiling you will see a black or darck spot in the center of the circle of light about 3 to 6 inches across. When taped to a gun barrel, the bullet will strike in the center of the black dot in the light. All I had to do was spray them as if it was a water hose; there was no need to use the gun sights. I was not happy to see that I did not get front page coverage". So he claimed to have used a sighter at Lake Herman Road, suggestive that he was going to need it. Had he just approached the Rambler at Lake Herman Road and shot them through the window, what need would he have, to have taped a pencil flashlight to the gun barrel. It was suggestive and indicative of a killer that wanted to 'hunt' his victims in the open".
Gregory Haugevik stated "This was the only scene in which there were essentially zero witnesses.. Killer could've been wearing a costume a la Lake Berryessa for all we know...". 
This has been touted before, but flies in the face of everything we have come to assume about the Zodiac murders. His first two murders were completely different to his third attack at Lake Berryessa. But were they?. We know nothing of the murder of David Faraday and Betty Lou Jensen, other than where the evidence, and eyewitnesses, either side of the crime, point us. Unlike the final three attacks, there were no direct witnesses to the Zodiac Killer at the actual crime scene, while it was in progress.

The Lake Herman Road attack on December 20th 1968, unlike the Blue Rock Springs, Lake Berryessa and Presidio Heights attacks had no direct witnesses to the actual crime in progress. The only thing we have to piece together what happened that night are the eyewitnesses before and after the crime took place, the position of the victims on the gravel turnout and the ballistic evidence, in regards to the shell casing distribution at the scene. When James Owen passed the Lake Herman Road turnout at 11.14 pm, he reported seeing two cars parked alongside each other approximately 10 feet apart and nobody in or around the vehicles. At 11.20 pm Stella Borges on her journey to Benicia passed the turnout and discovered the victims David Faraday and Betty Lou Jensen lying on the ground. This would have given the Zodiac Killer a perceived six minute window of opportunity. However in a subsequent statement on December 24th 1968 James Owen states the cars were 3-4 feet apart, again reiterating that he saw nobody in the turnout, adding that he thought he heard a gunshot when he was approximately one quarter of a mile past the turnout. This would equate to 30 seconds traveling at 30 mph. But there are problems with this statement. Nobody can say with absolute certainty exactly what happened on that cold December night back in 1968, but what is more likely to have happened can be evaluated following the crime scene evidence and a liberal sprinkling of common sense.          

One perceived order of events is the Zodiac Killer parked his car alongside and to the right of the victims Rambler, exited his vehicle, and fired a warning shot into the air. He then approached the Rambler and fired two more shots into the vehicle. One into the right rear window, shattering the glass and lodging in the floor mat by the left rear wheel well. The second struck the headliner of the 1961 Rambler. Each of these shots were designed to herd the couple from the car.
​Betty Lou Jensen and David Faraday were forced out of the front passenger side door. Betty Lou Jensen exited first, followed by David Faraday. The widely believed order of events, is that as David Faraday left the vehicle he was ushered somewhere close to the rear wheel of the Rambler and shot in the left side of his head. Then Betty Lou Jensen, either ordered by the Zodiac Killer to run, or through sheer terror fled westwards, before being struck down by 5 bullets to the right side of her back, finally falling backwards and expiring  28 feet to the rear of the Rambler.
​If this sequence of events is correct then James Owen's version of events is wrong. If James Owen passed the turnout and saw nobody in and around the vehicles, then it is probable that the Zodiac Killer had heard or seen the headlights of James Owen's approaching car, subsequently forcing the couple out of sight, possibly between or behind one of the vehicles. Had the Zodiac Killer not done this, James Owen would have seen the couple in their Rambler.
​Logic tells you that if the Zodiac Killer had seen or heard James Owen's car approaching, he would not have fired off warning shots to force the couple from the car, because James Owen would have heard the gunshots, as he supposedly did one quarter of a mile past the turnout. If James Owen had heard a single gunshot one quarter of a mile past the turnout, he most certainly would have heard 2 or 3 warning gunshots as he was approaching it, which he didn't. 
The warning shots into the Rambler had to be out of audible range to James Owen as he approached the turnout. This meant the Zodiac didn't kill the couple immediately, as James Owen would have seen the stricken couple lying on the turnout. The fact James Owen spotted nobody in the turnout, indicated the Zodiac may have had dialogue with the couple for a period of time after he forced the couple out of the Rambler, then saw Owen's car in the distance, and was forced to hide the couple behind the vehicles and out of view.  
Had the gunshot heard by James Owen after the turnout been the first shot that night to David Faraday's head, then there was a delay before he shot Betty Lou Jensen, making these shots beyond the audible range, it would have negated the purpose of any warning shots into the Rambler subsequently, as both David Faraday and Betty Lou Jensen would have already exited the vehicle and been murdered. The following is for consideration: 
The time is around 11.12 pm, James Owen is one mile and two minutes from the turnout, he is out of earshot, and the Zodiac Killer has just forced David Faraday and Betty Lou Jensen from the Rambler by firing at the vehicle. The next two minutes are unknown, but Zodiac has not yet begun his deadly attack. There may have been some form of dialogue between the subjects similar to the Lake Berryessa attack. The Zodiac Killer spots headlights in the distance and the sound of James Owen's car approaching the turnout. He forces the couple out of view and James Owen passes by. However the mood of the conversation between the subjects has convinced David Faraday the situation is about to turn deadly, so as they rise back to their feet he makes his move, either striking out at his assailant or reaching for the gun and a scuffle ensues. After 20-30 seconds the Zodiac Killer has positioned the gun at David Faraday's head, discharges the fatal shot and David Faraday falls to the floor 90 degrees from the Rambler, with his feet nearly touching the right rear tire of the vehicle. His class ring dislodged from his finger in the struggle. James Owen is now 30 seconds past the turnout and hears this shot. It is inconceivable that the Zodiac Killer would have wanted to fire off this shot voluntarily just 30 seconds after James Owen had passed the turnout, still within earshot, however events never went to plan. The Zodiac Killer turned to Betty Lou Jensen and a short dialogue ensued. In all likelihood she may have pleaded for her life or been frozen in fear, but as we know the Zodiac Killer was devoid of mercy, forcing the helpless Betty Lou Jensen to run for her life, and we know the rest. This delay of approximately 30 seconds or more, meant James Owen is now at least half a mile away, and with the radio on low failed to hear the final five shots.  

The police sketches of the scene are varied, in that when you overlay them the Rambler changes position in relation to the environment. In other words they are not totally accurate, although the depiction on the left combines all the relevant details. There were 10 shell casings retrieved (marked in red) and 8 bullets recovered. 5 that struck Betty Lou Jensen, 2 from the Rambler and 1 from David Faraday. Two bullets were never found. It can be noticed that all but one of the shell casings were found in a cluster, suggesting the killer was standing between the cars when he shot both victims. If he had shot David Faraday first, he would literally have had to shoot Betty Lou Jensen from this location in close proximity to David Faraday's body.
​Robert Graysmith stated that the Zodiac Killer chased Betty Lou Jensen across the turnout, shooting as he went. This is not what happened, as the expended shell casings would have been found along the path between the rear of the Rambler and where she eventually fell and as you can see from the diagram there are none. It was also stated that the Zodiac Killer rounded the Rambler to the left side and fired into the left rear tire, however no shell casings were ever found to the left of the Rambler. It is often thought in crime scenes regarding  a right handed person, that shell casings would be ejected to the right and rear of the shooter, but it is not that simple, dependent on the killer's hand position and movements. 
This is an extract from Force Science News that shows this is not always the case, depending on a number of factors. 
"Depending on those variables, extracted casings can end up virtually anywhere at a shooting scene," explains Dr. Bill Lewinski, executive director of the nonprofit FSRC. "Their final location alone will confirm virtually nothing about a shooter's firing position unless you know how he was holding his gun and how he was moving at the time of discharge. By changing those characteristics, you can place shells all over the place." 
But what we do know, is that the Zodiac Killer must have had a similar hand position when he lined up to shoot Betty Lou Jensen five times in the back, with the shell casings falling between the two vehicles. Had he kept his aim true and steady, then the wounds on Betty Lou Jensen's back make perfect sense from a ballistics standpoint. There was one grain of gunpowder found by the uppermost hole of her dress, suggesting this was the first shot. The remaining shots descended her back as she ran for her life. This, along with the positioning of the bullet casings makes it fairly evident the Zodiac Killer was not chasing after Betty Lou Jensen across the turnout in a westerly direction.    
There was one stray casing found 20 feet south of David Faraday's head. It would have been beyond the unknown car on the passenger side, seemingly an unusual place for a shell casing to have been found. It is not inconceivable that the Zodiac Killer fired the first shot into the Rambler that night the instant he opened his door. The expended casing ejecting to his rear, striking the top of his vehicle and coming to rest a few feet from his passenger side. 
James Owen gave us two distances between the Rambler and unknown car, firstly he said 10 feet on the 21st December 1968, then changed it to 3-4 feet in his statement on December 24th 1968. Had the distance been 3-4 feet, we would have to assume that as David Faraday fell after being shot, he would have collided with the Zodiac's car. An average size person of 5'8"-5'10" could not lie 90 degrees to the Rambler, with their feet virtually touching the right rear tire of the vehicle, without lying under the adjacent car parked only 3-4 feet away. James Owen seemed unsure of the distance between the vehicles. He also stated that he "thought he heard a shot". If he was wrong on both accounts then the whole story changes once again.

Here we will be running over some old ground, but concentrating primarily on the 13 Symbol cipher mailed to the San Francisco Chronicle on April 20th 1970, showing how its symmetry, its connection to the 340 Cipher, Button letter code, 13 Hole postcard, Halloween card and Pines card can be intertwined within its design. The Zodiac Killer may have been heavily influenced by mathematics and religion, developing his own code key- and this can be shown throughout the 13 Symbol cipher, that was intrinsically born out of symmetry and the religious leanings of the Zodiac Killer.

His key was developed by splitting of the alphabet, A through to M and N through to Z. We can see that the 13 Symbol cipher begins with an A and ends with an M. So, what we will do first, is place the alphabet alongside the 13 Symbol cipher and see if we can find any organization or patterns that exist using simple mathematics.