The murders threw up many theories, but one centered on a motive of jealousy, that possibly two individuals may have been responsible for the slayings. One young man was brought into the suspect list after he and two accomplices were found to have raided and vandalized a local residence five months earlier and may have become jealous, upon hearing of the relationship between Betty Lou Jensen and David Faraday and the early reports that two sets of ballistics had been found at the crime scene, from .38 and .22 weaponry. Friends of the couple were interviewed, to search for a motive, in a 'shake the branches' and see what falls out technique, but alibis held strong and no credible suspects landed at their feet.
Sgt Jack Mulanax, in charge after the Blue Rock Springs attack some 6 months later, believed all four attacks to be the work of the Zodiac Killer, a view not held by Sgt John Lynch who also investigated the Zodiac murders, concluding that the Lake Herman Road murders were separate to Blue Rock Springs, Lake Berryessa and Presidio Heights. The Lake Herman Road murders were belatedly attributed to the Zodiac Killer after the arrival of three letters to the Vallejo Times, San Francisco Examiner and San Francisco Chronicle on July 31st 1969, along with his 'Debut of Zodiac' letter on August 4th, with the immortal phrase 'This is the Zodiac speaking'.
The Zodiac Killer laid claim to the Blue Rock Springs attack on Darlene Ferrin and Michael Mageau and the earlier murders in a phone call 40 minutes after the attack and by letter just 27 days after that fateful night. It is only then he corroborates us of his involvement in the Lake Herman Road murders seven months earlier. Taking into consideration these may have been his first murders, namely under the Zodiac banner, it seems unusual that a man gripped by the spotlight of attention would choose to wait more than half a year before announcing himself to the world, subsequently unleashing a barrage of communication right up to the Pines Card mailed on March 22nd 1971.
In the last article on this site, the small town of Benicia was earmarked as the likely residence of the Zodiac Killer, taking into consideration the timeline and movements of the killer, particularly after the first two attacks at Lake Herman Road and Blue Rock Springs. Again we will explore this possibility, based on the mailing dates of his letters. Previously we stated that a serial killer will often begin his murders in a place of familiarity, close to home, but not too close, to facilitate an escape route with minimal risk and speedy return to the safety of home, known in geographic profiling terms as a 'buffer zone'. What we noticed that his early crimes, based on a home residence in Benicia, began at Lake Herman Road, only 5 miles from southern Benicia, extending to 9 miles to Blue Rock Springs, 50 miles to Lake Berryessa and finally 40 miles to Presidio Heights, slightly shorter than Lake Berryessa, but nevertheless his crimes were becoming more spread, as he ventured outwards.
As his radius of murders widened, his immediate correspondence after each crime shortened. His first contact on July 31st 1969 was just over 7 months after the Lake Herman Road murders, but only 27 days after Blue Rock Springs, his murder of Paul Stine was the next furthest at 40 miles and he corresponded only 2 days later, when he mailed a swatch of Paul Stine's shirt to the San Francisco Chronicle on October 13th 1969, and finally with the Lake Berryessa attack, 50 miles and furthest from Benicia, he wasted no time declaring himself the killer, writing on the car door of Bryan Hartnell's Karmann Ghia minutes after the attack. In other words the further he was away from his home residence, the greater his compunction to mail, or in the case of Lake Berryessa to write, what is in effect useable evidence, to authorities sooner. He felt the risk was greatly reduced in police centering the investigation to letters and crimes with an increased 'buffer zone'. The need for a significant delay between the Lake Herman Road murders and the August 31st 1969 letters, was inherent of a man who knew he was just too close for comfort and the heat had to dissipate. To wittingly pull the investigation of the Lake Herman Road double murder away from the desired route it had taken, may have veered the focus elsewhere, indeed, somewhere closer to home and something the Zodiac Killer was keen to avoid.