There are many things to consider when using geographical profiling to narrow down an offender's home location, but on this occasion we will resort to basics. The 'least effort principle' is whereby people - in our case the Zodiac Killer - when faced with two or more alternatives with his decision making, will often opt for the one requiring the least effort . In terms of the Zodiac Killer, had he lived in Benicia and knew that young couples frequented the Lake Herman Road turnout, as well as Blue Rock Springs Park, and given that couples are available at both locations on any given night, he will choose the one nearest to his home. However, he will observe a 'buffer zone', described as an area around an offender's home residence that he will not operate, for fear, not only of being recognized, but drawing law enforcement onto his doorstep. For example: If the Zodiac Killer lived in Hastings Drive, Benicia, his buffer zone may be 6 miles by road or as little as 2 miles as the crow flies. See here. A serial killer usually begins his crimes close to home, somewhere he is familiar with, before he eventually gains in confidence and ventures further afield. So, if the Zodiac Killer lived in Benicia, he would use the 'least effort principle', 'buffer zone' and victim pool to select his first attack.

A recent survey in Germany studied the locations of serial killer victims in respect to the killer's home residence and found that 63% of the time the killer lived within a 6 mile traveling distance to the crime scene. So putting all these factors together we could expect the Zodiac Killer's first murders at Lake Herman Road on December 20th 1968 to be only a matter of a few miles from his house. Bearing in mind the timeline that night, given by eyewitnesses Stella Medeiros and James Owen, it was determined the Zodiac Killer after brutally murdering David Faraday and Betty Lou Jensen must have driven east after the commission of the crime and headed toward Benicia. Using this as our guide, there may be a good chance that if you were to travel by vehicle from the Lake Herman Road turnout toward Benicia in your car, you may be near or have already passed the home of the Zodiac Killer, within or close to this six mile journey.

It is a distinct possibility the Zodiac Killer had a standard Monday to Friday, 9-5 occupation, when you consider his four confirmed crimes. If he lived in Vallejo or Benicia, then the first two crimes at Lake Herman Road and Blue Rock Springs were close to his home. This makes perfect sense in respect to the 'least effort principle', as both of these attacks were on a Friday, a day he may have worked. His final two attacks at Lake Berryessa and Presidio Heights were further away, but both were perpetrated on a Saturday, a day he may not have worked. This would have given him more time and energy to plan a more distant and ultimately more daring attack. 

If we take the 'least effort principle', 'buffer zone' and the time constraints of his occupation into account, it makes San Francisco an unlikely home for the Zodiac Killer, assuming he remained in one location throughout his four attacks. If we take the mileage from the nearest point in San Francisco to the Lake Herman Road turnout, it is approximately 38 miles. See here. Therefore, the geographical profiling principle would be turned on its head. The Zodiac Killer would have finished work on Friday and have been prepared to throw the 'least effort principle' out of the window and create his initial 'buffer zone' at 38 miles or more when carrying out the Lake Herman Road attack. This would be followed by a 44 miles or more 'buffer zone' at Blue Rock Springs, and then he would have traveled even further, a distance of 80 miles to Lake Berryessa for his third attack, before finishing closest to his home residence with the murder of Paul Stine on October 11th 1969. It would mean he was committing three crimes in excess of 38 miles away, in less familiar areas, such as the rarely used Lake Herman Road, with less escape routes, as his opening gambit. In addition, he was prepared to expose himself even further by traveling on foot in a built up area, having just shot a taxicab driver and securing a 'trophy', all within the nearest point to his home residence.
The first two attacks also suggested the killer must have had prior knowledge that Lake Herman Road and Blue Rock Springs Park were popular haunts for courting couples, unlikely to have been known by a native of San Francisco - unless he worked in the locality of Vallejo or Benicia, or had previously lived there.            

Canter and Larkin (1993) proposed the 'circle theory of environmental range', that suggests a circle drawn around the crime scenes (four in our case) should result in the killer's home residence lying somewhere within this circle. It is then a matter of narrowing it down using the principles detailed above. The killer generally starts his crimes closer to home, yet in the case of San Francisco, this is the Zodiac Killer's final crime. It should therefore be one of the furthest from his home location. The Lake Herman Road and Blue Rock Springs locations lie extremely close to the center within the circle. This is not conclusive, but it is definitely food for thought when we further consider the immediate movements of our killer from Lake Berryessa to the payphone at 1231 Main Street in downtown Napa. The murderer would be traveling in a southerly direction, that would be on a collision course with the Vallejo/Benicia areas.

Furthermore, the unexplained 40 minutes after the Blue Rock Springs attack raises questions, considering the payphone was only 10 minutes journey time from the crime scene. If the killer had lived in San Francisco, he could have made this phone call anywhere en route with little risk. There would have been no reason for him to hang around Vallejo, spending 30 minutes longer than necessary to place the call to Nancy Slover, with all the risks this would have entailed. 

Another geographical profiling term is 'distance decay', that states the farther you travel away from the killer's comfort zone (their area of familiarity), the less likely they are to kill. Although we only have four crime scenes on our map above, it nevertheless would exhibit this trait, based on a premise of our killer living close to both Lake Herman Road and Blue Rock Springs Park. The cluster of pins in the map would therefore decay the further we traveled from the murderer's base location. It is hard to call the first two crimes a cluster, but so far they are more suggestive of a warm zone than San Francisco regarding  the circumference of our circle. It is true that many Zodiac letters were mailed from San Francisco, but this is more than likely where he worked, as opposed to where he lived, and he mailed these letters on his journey to and from work. Had he finished work at 5:00 pm on Friday afternoon in San Francisco and arrived back in Benicia or Vallejo sometime approaching 6:00 pm, the 'least effort principle' would now kick in. This was ultimately reflected in his choice of locations on December 20th 1968 and July 4th 1969. In fact, the further away his workplace was, the greater this 'least effort principle' would apply, not only because of tiredness, but the time constraints of traveling further afield. In all probability the Zodiac Killer lived in either Vallejo or Benicia - which leaves one final question.
​
Bearing in mind the double murder at Lake Herman Road on December 20th 1968 at the dead of night, with the killer having fired off at least ten rounds, probably having picked up biological transference from the brutal execution of David Faraday, carrying the smoking gun, having limited escape routes, and in all likelihood, heading for the safety of home, did he turn left to Vallejo, or right to Benicia. This may be the answer we are looking for.

See also:  
http://www.zodiacciphers.com/zodiac-news/the-first-phone-call
http://www.zodiacciphers.com/zodiac-news/springs-and-tuolumne
http://www.zodiacciphers.com/zodiac-news/four-minutes-behind   

Stepping into the shoes of a psychopath is never easy, and applying logic to the illogical is even harder, but for 40 minutes we will attempt to do this by tracking the Zodiac Killer's movements from the moment he left the Blue Rock Springs parking lot to the exact time he placed the first phone call to police dispatcher Nancy Slover at the intersection of Springs Road and Tuolumne. Of course, if the killer had driven to the payphone immediately after the attack on Michael Mageau and Darlene Ferrin, the phone call would have been received at approximately 12:10 am, however, it was recorded in the police report at 12.40 am, leaving a notable discrepancy. If you are one of the people who believe the killer was local to this area, rather than San Francisco, then this unaccounted time may be the most important clue of all, to narrow down a possible location for Northern California's most elusive serial killer.

As stated before, a serial killer usually starts his crimes close to home before venturing further afield, and although most letters were mailed to the San Francisco Chronicle, the traveling time and apparent knowledge of the infrequently used Lake Herman Road seemed to suggest our killer lived nearby and may have worked in San Francisco. But by examining the Blue Rock Springs Park attack in closer detail and following the timeline, it may take us closer to the killer's doorstep.

On the right is a map of the Vallejo/Benicia regions, showing one possible route the killer may have took that night. The circled red region may indicate a likely point of interest. But first, we will return back to the parking lot at Blue Rock Springs. After the attack on the defenseless couple the killer left the scene heading in the direction of Vallejo. When he traveled along Columbus Parkway he had a decision to make - does he turn left and head down Lake Herman Road, an unlit, quiet and secluded road - a road he knows well and one that he previously visited during the commission of his first crime, or head along Springs Road. Based on the previous testimony of Stella Borges, if the killer had turned left onto Lake Herman Road, the murderer would be now traveling in exactly the same easterly direction as he was after the brutal murder of David Faraday and Betty Lou Jensen some six months earlier.

If we believe these were his first two serious crimes, involving murder, then his first instinct after each crime must surely be to head straight home to reduce the burden of carrying the 'smoking gun', and remove any incriminating evidence, particularly after the close contact murder of David Faraday in the Lake Herman Road turnout. Of course, other options exist. After the Blue Rock Springs attack he may have traveled westwards towards Vallejo, but this presents a problem and possibly a conflict of interests. Why would the killer, realizing that shots may have been reported in the location of Blue Rock Springs, head into a region where there is a greater likelihood that responding officers would have been approaching from, including Ed Rust, who was patrolling in downtown Vallejo? The safer option would surely be to head down a quiet, dark road on the eastern fringes of Vallejo and Benicia in relative anonymity, and again, in the same direction he headed after the December 20th 1968 double murder. Had the killer lived in the Vallejo region, then of course he may have turned right, headed home, disposed of the 'smoking gun' and returned back to the payphone, accounting for the 40 minutes of time between the attack and payphone call.. But if this were the case, why didn't the killer head towards this region after the Lake Herman Road attack, rather than away from it, further from home. If the time delay of Stella Medeiros and James Owen passing the Lake Herman Road turnout was greater than the one widely touted, then this assumption may be weakened, allowing the Zodiac to head toward Vallejo without having to pass Stella Medeiros en route.   

The Zodiac Killer in his correspondence mentions Vallejo several times, including the July 31st letters, the 'Debut of Zodiac' letter (three times), 'Bus Bomb' letter and disputed 'Fairfield' letter, but despite the first murders being committed in Benicia, he seemed reluctant to ever mention this area, instead, forcing home the Vallejo connection. If he mailed his letters away from his doorstep in San Francisco, why the over emphasis on Vallejo, along with placing a phone call using a Vallejo payphone? Was this designed to center the focus towards the Vallejo area, and in particular the region around the payphone?  
This topic has been covered before in 'East to Benicia' and 'Springs and Tuolumne', but this time we try to narrow down the Zodiac Killer's exact route after the Blue Rock Springs attack with a little more detail. 

After the Zodiac Killer reached the end of Lake Herman Road, he turns right through the industrial area of Benicia and heads towards the Carquinez Strait Bridge. He now could head over the bridge to the area of Martinez (but not much further if we are to stick to the 40 minute window we have available) or he could join Interstate 780, before turning into the red circled region of Benicia shown on the map. The only reason for believing this to be a more likely home location than the Martinez area, is that the timeline is far tighter from beyond the Carquinez Strait, and this region is closer to Lake Herman Road and Blue Rock Springs, bearing in mind his apparent knowledge of the area. It is equally possible that the Zodiac Killer took Old Lake Herman Road and East 2nd Street into Benicia. Either way, it affords the killer approximately 10-15 minutes at his residence to conceal his weapon, possibly change his attire and ready himself for the journey to place the phone call he desperately wanted to make.

The easiest and quickest way to the intersection of Springs Road and Tuolumne, would be to join Intestate 80, before exiting somewhere by Solano Avenue. The Zodiac Killer then only had to spend as little as four minutes on the minor roads of Vallejo (not including the placement of the phone call), thereby reducing the risk of detection and giving him as little as two minutes immediate access to a main highway to make good his escape back to Benicia. 

The phone call from Vallejo and the dialogue in his letters, such as: "In answer to your asking for more details about the good times I have had in Vallejo',.... 'I did not leave the cene of the killing with squealing tires + raceing engine as described in the Vallejo paper'.....'I was in this phone booth having some fun with the Vallejo cop' and "Ask the Vallejo cop about my electric gun sight which I used to start my collecting of slaves", may have all been designed to point us in this direction, when in actual fact, he lived in Benicia all along.

The killer of taxicab driver Paul Stine claimed in his October 13th 1969 letter "I am the murderer of the taxi driver over by Washington St and Maple St last night, to prove this here is a blood stained piece of his shirt." 
In a previous article, available by clicking the photographic link on the right, we showed an order of events that seemed to suggest that Paul Stine was actually murdered one block earlier, at the intersection of Washington and Maple Streets, which appeared to concur with the Zodiac Killer's claims in the October 13th 1969 letter.

The Zodiac Killer may have shot Paul Stine as he was performing a run-through stop (as this was believed to be an unscheduled fare), en route to a dispatched call at 500 9th Avenue. The bloodstains on Paul Stine's shirt and the fingerprints on the driver side door panel, as well as other points of interest, seemed to suggest that after Paul Stine was shot the taxicab motioned forward out of control. The Zodiac Killer, determined to secure a trophy for his master plan, quickly exited the rear of the taxicab, accessed the driver side door, and after stepping over Paul Stine, leaned against the body to gain some form of limited control and coast the taxicab to the Washington and Cherry Street intersection, where he secured his 'trophy'. For a more detailed account of this sequence of events, along with blood pattern analysis, click the image.

It is a 'most dangerous game' trying to apply logic to the most illogical of  killer's, but some things the Zodiac Killer did were logical. His attempt to remove fingerprints from the inside of taxicab, including the compartment area, along with both exterior doors, were born out of logic, because he did not want to get caught. So is it possible that the removal of the wallet and keys were taken from the scene for the exact same reason, they harbored his fingerprints. We know that the three teenagers from across the street thought they saw the murderer searching through the victim's pockets, and this in all likelihood is correct, as Paul Stine's wallet had been taken. 

If you were the killer of Paul Stine on October 11th 1969 and you were determined to secure a trophy to prove you were inside the taxicab that night, what is easier, searching the victim's pockets for a personal photograph, a driver's license or some other form of ID card, or carefully tearing a rectangular section from the victim's shirt, which would certainly take far more time, and ultimately increase the risk of detection, or at worst capture. The killer wanted proof and he wanted it fast. If he had found Paul Stine's driving license, it seems bizarre he would then start searching for further trophies. This would seem to suggest he found Paul Stine's wallet, but it did not contain the proof he needed, so proceeded to remove the shirt piece. The removal of the shirt piece enabled the Zodiac Killer mail off numerous sections to the newspapers, which did in three of his next four communications on October 13th, November 9th and December 20th of 1969. This would place the letter writer and the murderer of Paul Stine under one banner - the Zodiac Killer.

​The Zodiac Killer never took any trophies from his first three attacks at Lake Herman Road, Blue Rock Springs Park and Lake Berryessa, however, he was determined to convince us he was the killer, by stating facts supposedly only known to him and the police when he mailed the first four letters to the Bay Area newspapers. He was determined to convince us even more when he placed two phone calls after the second and third crimes, and furthermore by writing on the car door at Lake Berryessa. Had he killed taxicab driver Paul Stine on October 11th 1969 without mailing a section of Paul Stine's shirt on October 13th 1969, after an altogether different crime, there would be little to suggest this murder as the work of the Zodiac Killer. He needed something more to ultimately link him to the crime, and what better way than taking the crime scene into his correspondence. He never sent parcels or packages as far as we know, but stuck rigidly to letters and postcards, that afforded him ultimate anonymity. The choice of mailing a shirt piece was ideal in this respect. 

The police report stated: "Suspect should have many bloodstains on his person and clothing, suspect may also be in possession of the keys to the Yellow Cab, possibly his wallet belonging to the victim." But why did he take these items? They were never mailed to the newspapers or police by the Zodiac Killer, and would have been too bulky to have been received via the standard letter route. Despite numerous letters subsequent to this murder, the keys and wallet were never mailed. It may not be conclusive, but in all probability he took the keys and wallet for a totally different reason. A reason that had nothing to do with securing further trophies, and was nothing more than simple common sense to evade capture.          

The Zodiac Killer was observed wiping down various sections of the taxicab, presumably to remove fingerprints. If he had handled the wallet, it too would have contained fingerprints, possibly on its front, rear and inside, as holding and searching the wallet would have necessitated the use of both hands. The crucial difference between the taxicab and the wallet, is that he couldn't realistically take the taxicab home with him, so fingerprint removal had to be done immediately. It is not easy to hold a wallet and wipe down all its surfaces without depositing further prints, so the simplest solution is to take the wallet with you, which is ultimately what the Zodiac Killer did. But why take the keys? If not for the procurement of a trophy, then in all probability because he touched the keys also. The items he touched that were not actually bolted down to the taxicab were easier and quicker to remove, than spending extra valuable seconds wiping them down. The only question left to ask, is why did he touch the keys in the first place? The answer may lie one block east.

We have considered that after killing Paul Stine at the Washington and Maple Street intersection, not everything went to plan and with the taxicab motioning forward out of control, the Zodiac Killer had seconds to react, by accessing the front section of the vehicle and setting the taxicab back on track. It is here things may have unfolded slightly differently to the previous analysis, albeit not much. It was to be the very reason he took both the wallet and the keys one block later. Although this is sheer conjecture , it again fits with the known facts. When the Zodiac Killer attempted to regain control of the errant taxicab at the Washington and Maple Street intersection, the car may have stalled, and he was forced to restart the engine. His fingerprints were now in evidence and the rest is history.

Richard Gaikowski was a civil rights activist, newspaper journalist and filmmaker born in Watertown, Codington County, South Dakota on March 14th 1936, but received further unwelcome attribution after his death in 2004 from an anonymous source, only known to the world under the pseudonym of 'Goldcatcher', a man catapulted into Zodiac Killer folklore by Tom Voigt from the hugely successful website Zodiackiller.com. Off the back of this informant, Richard Gaikowski has posthumously been propelled to one of several high profile suspects in the notorious Zodiac killings from December 20th 1968 to October 11th 1969 - but how fair is this new found attention. Well, if you take on board the credibility of the informant and the anonymity that surrounds him, it may tell you all you need to know. Anybody can throw stones from the shadows, and the evidence linking Richard Gaikowski to the Zodiac Killer is as weak as it gets, culminating in Nancy Slover, the police dispatcher who took the phone call from the Zodiac Killer on July 5th 1969, being played a recording of Richard Gaikowski's voice nearly 40 years after the Blue Rock Springs attack, and being utterly convinced the voice was the same one she heard just 40 minutes after the deadly double shooting.

The circumstantial evidence lined up against Richard Gaikowski, as it is with many suspects, is a simple case of choosing the facts that fit and blatantly disregarding anything that casts doubt on the suspect's perceived guilt by not presenting it for public consumption. The questionable movements of Richard Gaikowski from the latter part of 1968 to the early months of 1969 has come under widespread scrutiny, on whether he was even present in Northern California, or for that matter the USA during the Zodiac Killer's first confirmed attack on December 20th 1968, resulting in the double murder of David Faraday (17) and Betty Lou Jensen (16) in a remote Lake Herman Road turnout. Surely, before you project a suspect into notoriety, it must be imperative you know without doubt that your charge was even in the same country during each or any of the confirmed murders. This is, at the very least, the first thing you should do. Not being 100% sure is simply not enough.   

In 1966 Richard Gaikowski worked for the Albany, New York, Knickerbocker News publication, immersing himself in the political issues of the day. At the same time the civil rights group The Brothers, an African/American collective of around twenty members, were actively involved with some measure of success in improving social housing, public schools, police brutality issues and other projects in Albany's North and South End and Arbor Hill, gaining close attention when they highlighted the alleged Albany Democratic vote buying scandal in November 1968. Members included Leon Van Dyke, Gordon Van Ness and Clarence Williams - and their paths crossed with Richard Gaikowski as he was a frequent visitor to their Albany headquarters. The group followed the Martin Luther King policy of non-violent protest, something that courted admiration from Richard Gaikowski, who himself detailed the struggles of black minorities against the backdrop of racial injustice that permeated the American society of the day. The Brothers ran the Albany Liberator newspaper from 1967 to 1971. But things were about to change during the turbulent year of 1968. The assassination of Martin Luther King on April 4th 1968 in Memphis, Tennessee, followed by Robert Kennedy's assassination on June 6th 1968 in Los Angeles, California, would in two brief months change the political landscape dramatically. Richard Gaikowski, disillusioned by the year's events, meant his stay in Albany and the Knickerbocker News was on borrowed time, as was the lifespan of The Brothers, which dissolved at the beginning of the 1970s.

In late September 1968, Richard Gaikowski, in his own words, left for Europe. At approximately the same time the political organisation People's Democracy was being formed for Northern Ireland's Catholic minority at Queen's University Belfast on October 9th 1968. The struggle of minorities once more must have pricked the attention of roving journalist Richard Gaikowski, who found himself at a loose end. Shortly he would travel to Northern Ireland to cover the unfolding events, where he witnessed the Belfast to Derry march violence on Queen's University students as they traveled as part of the People's Democracy. SEE HERE.

Two notable dates were firstly, the beginning of the troubles on Saturday October 5th 1968, when members of the Derry Housing Action Committee and the Northern Ireland Civil Rights Action Association were prevented from marching by the Royal Ulster Constabulary, when they baton charged the crowd in Derry.

The second important date was the four day Belfast to Derry January 1st 1969 march, by approximately forty members of the People's Democracy. Interestingly, this march was styled on the 54-mile Martin Luther King Selma to Montgomery march of 1965, that prided itself in peaceful protest. However, like the first Selma to Montgomery gathering on March 7th 1965, the Belfast to Derry march on January 1st 1969 erupted into violence when they were attacked many times by loyalist crowds along the route - the worst of which took place on January 4th 1969. Richard Gaikowski, in part a civil rights journalist, in all likelihood drew parallels with the struggles in America, the connection of a Martin Luther King style march and, as had occurred many times previously, feared violence would yet again rear its ugly head. He felt compelled to cover it.

In the newspaper clipping above, dated Friday January 31st 1969, it states "Special Report from Belfast : The bricks are flying in Northern Ireland. The Catholics are singing "We shall overcome" and a vociferous Protestant group rallies against "popery". The situation is explosive. Richard Gaikowski, former reporter for The Knickerbocker News, has been on the scene of the protests and rioting. He tells about them in an article that will appear tomorrow on the editorial page of The Knickerbocker News'". It is clear from the article, it mentions Richard Gaikowski has been on the scene of the protests. The question being, was he present in Northern Ireland for the entire month of January 1969? - it appears a distinct possibility. He left for Europe in late September 1968, the troubles in Northern Ireland began on October 5th 1968, and the four day march between Belfast and Derry, indicated in 'My Albany Sojourn', took place on January 1st 1969.
If he remained in Europe and Northern Ireland for this period, then Richard Gaikowski could not be responsible for the Lake Herman Road murders on December 20th 1968 and all but ruled out as the Zodiac Killer. 

If he was the Zodiac Killer, we would have to assume, that after murdering and depriving two teenagers the freedom to enjoy the rest of their lives just before Christmas, he then boarded a flight to Northern Ireland to cover a freedom march for a better tomorrow. It certainly makes for a good cover story. Possibly his newspaper articles were forged and he was never in Northern Ireland. Enter the conspiracy theorists.    

The Zodiac Killer began his series of crimes with the double murder of David Faraday and Betty Lou Jensen on December 20th 1968, followed by the Blue Rock Springs attack on July 4th 1969, killing Darlene Ferrin and seriously injuring Michael Mageau. The killer confirmed these murders with details provided in three letters he sent to the San Francisco Chronicle, San Francisco Examiner and Vallejo Times Herald on July 31st 1969. His next attack would be in the remote region of Lake Berryessa on Bryan Hartnell and Cecelia Shepard and although there appeared to be no reference to this crime in any of his subsequent correspondence, he wasted no time laying claim to the lakeside attack, writing on Bryan Hartnell's car door within minutes of the crime. His final confirmed murder was that of Paul Stine at Presidio Heights on October 11th 1969, only fourteen days after the Lake Berryessa attack and one cannot help thinking his focus had turned quickly after his third attack, straight into the planning phase of the Presidio Heights murder, after all his dramatic costume driven attack and the recollection of surviving witness Bryan Hartnell, had given him all the publicity he could have wished for. Again, after the Presidio Heights murder he wasted no time in contacting the newspapers, writing to the San Francisco Chronicle only two days later. In other words, his first letter immediate of three of the crimes, laid claim to each one of them, with the exception of Lake Berryessa, however he still laid claim to it, in the form of written communication on the car door. Therefore, although questioned as a Zodiac crime, it made perfect sense to analyze his immediate correspondence after the Modesto abduction of Kathleen Johns and see if this cryptic letter in any way suggested a link to it.
This letter contained the 13 Symbol Cipher, mailed to the San Francisco Chronicle on April 20th 1970, just one month after the Kathleen Johns incident on March 22nd 1970.  

Technically a full moon is really only full for an instant in time. As we approach a full moon it is said to be waxing and as it diminishes it is said to be waning. A Waxing Gibbous denotes 95% illumination approaching a full moon and a Waning Gibbous denotes 95% illumination as we leave the full moon, everything in between can be regarded as varying degrees of a full moon. 
Therefore in the calendar above there is one full moon phase in Aries, before the Zodiac sign of Taurus takes over on April 20th, 21st and 22nd. This may explain the 3 to 1 configuration present on the 13 Symbol Cipher. We now have seven dates of relevance, March 22nd 1970, April 19th, 20th, 21st and 22nd, July 24th 1970 and March 22nd 1971, but whether any significance can be attributed, remains questionable. 
The March 22nd 1971 Pines Card may also have strong ties to the Zodiac horoscope signs, in its very wording and ultimately provide us with a further link back to the 13 Symbol Cipher and its three circled symbols once again. SEE HERE.

It has often been speculated upon, that four of the symbols in this cipher may be interpreted as three circled Taurus symbols (shown in red) and one inverted Aries symbol (shown in blue). But how could these four symbols in any way connect to the Kathleen Johns abduction.
The following observation will not claim a solution, just a line of thought to be considered for discussion.
In this letter the Zodiac Killer claimed to have 'killed ten people to date'. Had he murdered Kathleen Johns and her infant daughter Jennifer, this total would have read 12.
Kathleen Johns was abducted on March 22nd 1970 and on the following anniversary of this crime, March 22nd 1971, the Pines Card was received at the San Francisco Chronicle, claiming to have 'Sought victim 12'.
There are four crucial dates at play here. March 22nd, detailed twice above, April 20th 1970, the mailing date of the 13 Symbol Cipher and July 24th 1970, the date of the correspondence the Zodiac Killer mailed, claiming responsibility for the abduction of Kathleen Johns. Bearing in mind the Zodiac horoscope signs, possibly present on the 13 Symbol Cipher, were the dates on the Zodiac calendar in any way relevant to these events.
Firstly April 20th, the 13 Symbol Cipher date is the beginning of Taurus on the Zodiac calendar. The abduction of Kathleen Johns on March 22nd 1970 is one day after the beginning of Aries on the Zodiac calendar. The Kathleen Johns letter on July 24th 1970 is one day after the beginning of Leo on the Zodiac calendar. Three horoscope dates, all within one day of the Zodiac Killer timeline. Four, if you include the Pines Card anniversary.       
The 13 Symbol Cipher was sent in the April of 1970 to the San Francisco Chronicle, so let us look at at the Moon phases and lunar calendar of San Francisco from the relevant time period. But before we do, it is important to note that the Zodiac Killer circled his three Taurus symbols and the symbol for a full moon, is basically a white circle. 

We are fast approaching the 45th anniversary of the date the 340 Cipher was mailed to the San Francisco Chronicle on November 8th 1969 and so far there has been no viable solutions uncovered, by either man or machine. Many claim to have discovered its secrets, but invariably it does not take long to see through the flaws, which often involve the claimant entering the 340 Cipher with preconceived ideas and forcibly extracting the result that suits their purpose the best. One such example was the Earl Van Best Jr case, when it was claimed by Gary Stewart that his fathers name was present in each of the 13, 340 and 408 Ciphers, on first glance it appears promising, but when you scratch just beneath the surface, you realize it means absolutely nothing. The human brain searches for patterns and invariably you can find them if you look hard enough for long enough. Dave Oranchak, from the Zodiac Killer Ciphers website, is probably one of the first port of calls you should make when it comes to deciphering techniques and has posted many interesting articles on this very subject, including the Earl Van Best Jr topic and outlines the faults of seeking patterns, along with the use of anagrams to decode the various ciphers.
To visit Zodiac Killer Ciphers CLICK HERE or read the standalone article 'The Most Pattern Seeking Animal of All' to understand this concept.

If a claim is made that a particular cipher has been solved, then almost without fail you know it hasn't. This overused term has to be treated with the utmost scepticism, as the claimant is invariably wearing very narrow blinkers and will defend their claim to the death, even when confronted with the unpalatable truth, that they have very little to nothing in the way of a solution. The article 'The Most Pattern Seeking Animal of All' by Dave Oranchak sums up perfectly the flaws in the techniques used, when pinning at least five murders firmly at the doorstep of Earl Van Best Jr, partly based on bad science. However, when the first books start rolling off the shelves, none of this really matters does it, sensationalism sells, the cold harsh reality of nothing is far less appealing.
Nevertheless, questions remain on whether the 340 Cipher is indeed a complete cipher or has any links to any of the other Zodiac correspondence he sent us, subsequent to November 8th 1969.
There was the Jos Kirps theory pointing out the Halloween Card, Paradice and Slaves connection here. We took this one stage further, to place By Knife, By Gun, By Fire and By Rope in the four Zodiac quadrants of the 340 Cipher here. Albeit several of the letters fall on the intersecting lines. Did the Zodiac himself intend the 340 Cipher to be dissected into four quadrants, after all he placed at the very heart of the cipher an addition or cross point, where the intersecting lines of the crosshair would have to pass through and on the very same tenth line, on each side, he gives us the outer edges of the crosshair, in the form of two hyphens. The foot of the crosshair, runs over the Zodiac symbol on the 20th line, in the 10th position. Are these deliberate actions on behalf of our killer or a simple case seeing of things that were never intended.
Sticking with the Halloween Card, an emphasis is placed on the number 14, the word 'BOO' is present and many crescent moon eyes are spread across the card. The 14th line of the 340 Cipher can be perceived to have the word BOO in reverse, comprised of half moons or half circles. Again, was this intended or just a vivid imagination and the search for patterns or correlations.
There is an Exorcist Letter connection on the sixth line of the 340 Cipher and the possible reason behind his upside down and elevated K on the January 29th 1974 letter. It married closely to this seemingly inadvertent correction on the sixth line.    

Simply dragging the two extreme Exorcist Letter symbols across the X axis and rotating the extreme right symbol 90 degrees clockwise, there appears a distinct similarity to the corrected portion of the 340 Cipher. Every visible symbol on the 340 Cipher has a close likeness to the Exorcist Letter configuration. Of course like we said above, this is not a reason to claim that anything has been solved. At best we may have made a possible link or at worst it may be a meaningless observation, that was never the intention of the Zodiac Killer, either way, the paralleling of many postcards and letters back to the 340 Cipher, remains a possibility, albeit a precarious house of cards, we should not reside in, for too long. 
The easy part, is the insatiable desire to search for patterns, the hard part is being able to stand back from your theory and view it with impartiality, something that is in all likelihood impossible to attain.
We are the 'Most Pattern Seeking Animal of All', but up to now the big picture has eluded us and it seems as distant now, as the day the Zodiac Killer crafted his masterpiece of evil, some 45 years ago. That is, unless you are one of the few that has declared 'The 340 Cipher solved'.

Many Zodiac researchers, amateur or otherwise, have developed their own favorite suspects over the last four decades, but invariably their belief is founded upon circumstantial evidence - and despite the fact many 'coincidences' seem to conspire together to push their suspect into the Zodiac Killer spotlight - it remains just a belief on the part of the researcher and has no basis in fact. Arthur Leigh Allen was a case in point, where multiple evidence lines seemed to suggest he was a strong candidate for the Zodiac murders, however, he was cleared after fingerprints and palm prints, along with DNA failed to match known samples retrieved from the Zodiac Killer letters. But despite this, there still remains lingering doubt on whether or not the samples held in evidence storage are actually that of the Zodiac Killer. Although, if multiple envelope seals and stamps were tested and one single partial DNA profile was unable to be excluded on each occasion, then unless a third party was the donor of saliva, either unwittingly or by consent, the profile of the killer would be close at hand.      

Touch DNA requires just a tiny number of cells to be retrieved, although it is a method fraught with contamination issues and the risk of false positives. When dealing with very small samples, the risk of compromising the evidence is greater, with polymerase chain reaction (PCR) often employed to amplify the DNA to create a larger sample for use by investigators.

In the case of the Zodiac Killer, any DNA he deposited on the letters, Lake Berryessa bindings or Paul Stine's taxicab, would today have provided enough DNA for analysis in CODIS (Combined DNA Index System), where the crime scene forensics could be entered into the database to search for a match to an offender already contained within it. However, this technique is totally dependent on the murderer having a previous conviction - otherwise a direct match could never be made. The use of a familial DNA profile has led to the closure of many cold cases, where a close relative has been found on the database and been linked to the current DNA being analyzed through family lines, resulting indirectly to the capture or identification of a criminal, sometimes decades after their crime was committed. 

Recent developments have revealed a tantalizing glimpse into the future, offering the possibility to deliver the Zodiac Killer's identity right into the palms of our hands. This has been covered previously, but it will be expanded here in a little more detail. This new technique removes the need for the Zodiac Killer's, or indeed any blood relative to have committed any previous or subsequent crimes - and effectively render the necessity of comparison tools such as CODIS redundant in this instance. It all comes down to the Y chromosome, passed from one generation to another, along the male lineage, in exactly the same manner as ones surname is also passed along. This would providie a correlation  between the Y marker and a man's surname, and thereby provide an alternative crime fighting tool - one that could provide us with the exact surname of the Zodiac Killer. This may not deliver the murderer of five people in Northern California on a platter, however, it would at the very least remove all but one of the high profile suspects, and most likely all of them from our Zodiac researchers lists. But how does it work in practice and what are its limitations?          

When a surname is carried down family lines for generations, an undeniable link exists between the surname and the Y chromosome, so when samples of DNA are retrieved from a current crime scene or from cold cases, they would have the Y chromosome isolated - and bearing in mind its close connection to family lineage - used to reveal a surname. This of course would require a database similar to CODIS, but this time when the Y marker is entered, the possible surname is availed to the observer. The police investigators would then use this to narrow down the field of view, regarding potential suspects and by the same note, remove suspicion from some entirely, thereby reducing man hours and wasted blind avenues.

Research has shown the rarer the surname, the greater the chance a common ancestor is shared. There are nevertheless drawbacks to any technique - in this case adoption and illegitimacy are two such examples - so caution needs to be applied.
The bottom line, is that the confirmed Y marker of the Zodiac Killer may just provide us with the name, that his ciphers promised, but always failed to deliver. 
     
http://www.sciencedaily.com/releases/2008/10/081007192526.htm
http://www.exploreforensics.co.uk/connecting-dna-your-surname.html