A link to this article is available at the foot of the page, but here we will be examining a different possible home location of the Zodiac Killer based on his movements after each crime, the distance he traveled using the 'least effort principle' and the standard working week.
His four confirmed attacks were Lake Herman Road on 12.20.68, Blue Rock Springs 7.4.69, Lake Berryessa 9.27.69 and Presidio Heights 10.11.69. These four attacks were committed on a Friday, Friday, Saturday and Saturday respectively, all at the weekend, suggesting the killer may have had a standard 9-5 occupation from Monday to Friday, only committing his murders prior to a day of rest.
Serial Killers often begin their crimes close to home in what is termed a 'comfort zone'. In other words areas that are familiar to them, such as their leisure zones, their place of work, the location of friends and family and functional activities, such as shopping habits. But not too close to risk identification or draw attention to their home residence. Once a crime has been perpetrated the main objective of the criminal is to return home or to relative safety. Killers will venture further away as they gain confidence, but generally not too far, as the least time they are traveling with possible crime scene transfer on their person, the better.
On the right is a map of the four crime scene locations and the traveling times to each, from Benicia, as this area will now become the main focus of our attention as the likely residence of the Zodiac Killer.
If Benicia was his residence for a reasonable amount of time his first two attacks at Lake Herman Road and Blue Rock Springs would have been relatively close to home, but committed in isolated locations that served to protect his identity.
If he worked standard occupation hours and finished work on Friday at 5.00 pm, the 'least effort principle' would come into play.
Murder was on his mind, but having arrived home late afternoon or early evening he conceivably wanted to travel the least distance possible as safety would allow.
His Saturday crimes of Lake Berryessa and Presidio Heights were considerably further, and being a rest day for the Zodiac Killer, the 'least effort principle' had less of a bearing.
Now we will examine the possible movements of the Zodiac Killer after each crime to narrow down a location for his home residence.
Eyewitness testimony from the Lake Herman Road murders suggested a very small window of time that the Zodiac Killer had available to him, in order to escape detection, but one eyewitness, that of Stella Borges, was the most crucial of all. A second eyewitness James Owen passed the turnout at what was calculated to be 11.14 pm and he saw no victims lying on the turnout. Stella Borges however, in a revised timeline, passed the turnout at approximately 11.20 pm and saw both victims David Faraday and Betty Lou Jensen lying on the gravel turnout.
Based on this chain of events the earliest the Zodiac Killer could have murdered the young couple and started to leave the turnout would have been 11.15 pm. Stella Borges, it was estimated left her ranch at 11.15 pm heading towards Benicia. She reported passing no vehicles en route. Therefore the Zodiac Killer could not possibly have headed towards Vallejo along Lake Herman Road. The only possible scenario using these timelines is the Zodiac Killer headed in an easterly direction towards Benicia and towards the relative safety of home.
After committing two brutal murders, possibly covered in biological material from the close contact murder of David Faraday, the sound of at least nine shots on a still dark night and almost certainly still in possession of a .22 weapon, it would have been unimaginably stupid and furthermore made little sense for the killer to head in the opposite direction to his home residence, thereby risking a prolonged period of detection, and in all likelihood ruling out Vallejo as a location point for Northern California's most elusive serial killer.
The attack at Blue Rock Springs was approximated no later than 12.04 am on the 5th July 1969, however the call the Zodiac Killer made to police dispatcher Nancy Slover at the payphone on Springs Road and Tuolumne was logged at 12.40 am. This payphone was located only a 10 minute drive from Blue Rock Springs. So what had the killer done during this time period. It is highly unlikely he would have sat stationary in his car in the area or outside the payphone waiting for his moment. After gunning down two people only 3.7 miles away this would have constituted insanity, even for an insane person.
Earlier we suggested it was highly unlikely the Zodiac Killer was a resident of Vallejo, so why head in this direction. Well clearly he knew the location of this payphone and his intent all along after this crime was to phone police and taunt the police, owning up to the recent shooting at Blue
The Zodiac Killer without doubt had planned to make a phone call to police in advance of the crime; this was his agenda, however this carried greater risks. The payphone was chosen because it was known to the killer and it was likely not too close to where he lived. But by making this phone call he would have extended his journey time back to Benicia, and although the nature of this crime, shooting both Michael Mageau and Darlene Ferrin through the passenger side window of their vehicle was less likely to have led to blood transfer, he would have still been in possession of a 9mm Luger, so a random stop by police near the payphone or on his way home would have presented a problem.
If he lived in Benicia or somewhere in that region, as his movements suggested after the Lake Herman Road double murder, then knowing the phone call would place him at greater risk, it is conceivable to believe he discarded the weapon before making the phone call to Nancy Slover, in his mind, reducing the risk of being stopped carrying the 'smoking gun'.
So the next thing to do is examine his possible movements during this timeframe.
He was familiar with Lake Herman Road, and in near isolation, free from prying eyes, it would have been a perfect disposal site for his weapon, particularly bearing in mind Lake Herman was situated near to his first murders. A round trip from Blue Rock Springs to Lake Herman with time spent to exit his vehicle, possibly remove his gloves, wipe down the weapon and toss the evidence into Lake Herman, before returning to the payphone at Springs Road and Tuolumne, would have taken approximately 30 minutes and nearer the time of 12.40 am, the time the call was logged. Any stop by police now, would have held far less risk. He could have traveled straight home after the attack at Blue Rock Springs, but his intention all along was to place the phone call and he was not to be denied.
In the phone call to police dispatcher Nancy Slover, the killer stated '"I wish to report a double murder. If you will go one mile east on Columbus Parkway to a public park, you will find the kids in a brown car. They have been shot by a 9 mm Luger. I also killed those kids last year.... Good-bye ".
This statement suggested only a limited knowledge of the area he was dealing with, as his directions were incorrect. He could have simply said ' I wish to report a double murder. If you go to Blue Rock Springs Park, you will find the kids in a brown car. They have been shot by a 9 mm Luger. I also killed those kids last year.... Good-bye '. But he chose not to do so. However this may be an over reading of the situation.
After his third attack at Lake Berryessa he made a second phone call at 1231 Main St, Napa, heading in a southerly direction and a direct route back to the Vallejo and Benicia region, suggesting a return to the locale of his first two crimes. This was the first time the Zodiac Killer had traveled any great distance to perpetrate murder. Is it possible a connection between Lake Berryessa and Lake Herman could be forged from a standpoint of recreation. Was the Zodiac Killer a keen fisherman in his spare time, hence his choice of remote areas that seemed to punctuate his early crimes.
His final confirmed murder was that of Paul Stine at Presidio Heights on October 11th 1969. This was in stark contrast to his previous attacks, taking place in a built up area with high risk. To commit such a brazen attack in a heavily populated location compared to his previous attacks seemed on the face of it an unusual choice, which is suggestive that he was very confident in these surroundings.
The red triangle region, drawn on the first map diagram suggests a comfort zone, incorporating Presidio Heights, Lake Herman and Lake Herman Road, Lake Berryessa, Napa, Springs Road and Tuolumne, Blue Rock Springs Park and Benicia. His residence could in theory fall anywhere within this triangle if we take geographical profiling to its basics. However it still leads us back to his first murders at Lake Herman Road on that lonely gravel turnout on December 20th 1968, in that the Zodiac Killer apparently corroborated by the timelines, headed home in an easterly direction toward Benicia. Either that or the Zodiac Killer had taken misdirection to a whole new level.