Frank Gasser, Robert Connelly and the Your's never reported passing this vehicle on their way to Benicia, after leaving the Marshall Ranch that night. The only way they could avoid passing this car (if James Owen passed the turnout at 11.14 pm), is if Frank Gasser, Robert Connelly and the Your's had left the Marshall Ranch at approximately 11.05 pm at the earliest, to avoid passing this vehicle as it entered Lake Herman Road at 11.07 pm. This vehicle would have reached the Marshall Ranch approximately 1 minute and 30 seconds after entering Lake Herman Road, putting it passing the Marshall Ranch at 11.08 pm and 30 seconds.
This tells us that Frank Gasser, Robert Connelly and the Your's must have left the Marshall Ranch sometime around 11.09 pm to avoid passing it on the road. Therefore, they all had to leave the Marshall Ranch at 11.05 pm or earlier, or 11.09 pm or after. None of the eyewitnesses, apart from James Owen, ever mentioned seeing another unidentified vehicle on the Lake Herman Road that night (ie: the mystery vehicle driving by the entrance to the Marshall Ranch at just past 11.08 pm). This indicates that nobody present at the Marshall Ranch that night saw a vehicle passing by (yellow circle on map). If this is correct (and using the estimated times given by these eyewitnesses in the police report), Frank Gasser, Robert Connelly and the Your's must have left the Marshall Ranch at 11.05 pm or earlier, to avoid ever passing this unknown vehicle on Lake Herman Road.
The raccoon hunters, Robert Connelly and Frank Gasser, drove out in their red Ford pick-up to the Marshall Ranch, located just beyond gate #10 of the Lake Herman pumping station. The pair spent most of the evening near the pump house, approximately 25 feet into the ranch land. The Your's drove to the Marshall Ranch gate, before turning around and heading back to Benicia. Neither party ever mentioned this vehicle.
We know from Captain Daniel Pitta's police report that Stella Borges, who discovered the victims in the turnout, flagged him down at about 11.25 pm in Benicia (time given in his police report), so he calculated the five minute journey back to the crime scene, indicating that she must have passed the turnout at approximately 11.20 pm. Since James Owen claimed in his statement he saw two cars side by side in the turnout and no bodies, common sense tells us, he must have passed the turnout slightly earlier, or at the very least, several minutes earlier, to allow enough time for the Zodiac Killer to have committed the double murder and escaped unnoticed before the arrival of Stella Borges. This window of opportunity was calculated at six minutes or less. More importantly, it would rule out the mystery car and driver as our killer - or would it?
Peggy Your stated "As they were driving west on Lake Herman Road at the turn off to the Benicia Water Pumping Station, she observed a Rambler station wagon parked with front end heading east, there were two Caucasians in the front seat, male and female, when the lights from the car came upon the station wagon, the male sat up in the seat. Mrs Your said it was a cold night and she noticed no frost on the station wagon".
She also stated "the girl was resting her head against his shoulder. When the lights of the car flashed on the Rambler, the subject in the car put his hands on the wheel".
However, despite James Owen describing the murder victims car as a "1955 or 1956 station wagon, boxy type, neutral color", he could not describe the other car at all, not even the color, despite claiming it was only 3-4 feet away in his second statement. What if these were not the only things James Owen failed to notice? In his revised statement, he told the police "He definitely saw two cars, a station wagon and another vehicle", but "he did not see anyone in the cars or around them.". But how definite was he? If he was mistaken, he may very well have already passed the Zodiac Killer by the Borges Ranch, as the murderer headed towards Vallejo.
The unknown driver of this car never came forward as a material witness to the crime - one has to ask why?
Lake Herman Road turnout to Borges Ranch on Google Maps.