Many observers believe this could be Zodiac - but what is the likelihood?
The 6:30 pm time that Dr. Rayfield parked his vehicle can be argued. Had this 'mystery man' been Zodiac, then he would have had to return up the hill, get in his vehicle and drive 0.8 miles south to where Bryan Hartnell's Karmann Ghia was located. The time would now be approximately 6:33 pm. The walk from the Karmann Ghia to the crime scene location is a quarter of a mile. The average walking speed is 3.1 mph (1 mile taking approximately 20 minutes). Therefore, the journey down to the location where Bryan Hartnell and Cecelia Shepard were lying, considering the terrain, would likely be upwards of 5 minutes - but we will go with this figure. The time is now 6:38 pm. He hides behind a tree and prepares for his attack (6:39 pm). The Zodiac then entered into a fairly long dialogue with the couple, proceeded to secure them with bindings and then stabbed them multiple times. The minimum estimation is 10 minutes, taking us to 6:49 pm. Returning up the hill and writing on the car door, a minimum of 6 minutes, giving us a time of approximately 6:55 pm when he begins his journey to Napa. The journey time for the 27 mile trip to the 1231 Main St, Napa payphone is estimated on Google maps at about 45 minutes. This would place the Zodiac Killer at the payphone at 7:40 pm - the exact time of the call to police dispatcher Dave Slaight. This timeline, however, is very optimistic, and does not tally exactly with the time of the attack, written as 6:30 pm on the car door of Bryan Hartnell. Nevertheless, it is within 10 minutes.
Dr. Clifton Rayfield reported that he had parked his vehicle four-fifths of a mile further north at 6:30 pm, likely one hour after Bryan Hartnell had arrived. So, Detective Ken Narlow's assumption that Zodiac was probably "stalking any singular parked cars along the route", would be extremely unlikely, as the Zodiac Killer would certainly have stumbled across the Karmann Ghia first, not Dr. Rayfield's vehicle. This could lend credence to the idea that Dr. Rayfield and his son saw the killer after the stabbing of the couple, hence the observation of a man wearing a "long-sleeved dark shirt with red coloring", that may have been blood. This, however, has a massive stumbling block. If the Zodiac Killer had discovered the Karmann Ghia first and parked alongside it, why would he be wandering around a hillside 0.8 miles north. He would simply have entered his vehicle and driven south towards Napa.
This would mean Dr. Clifton Rayfield and his son saw the Zodiac Killer roughly 20 minutes after they parked their vehicle, rather than shortly after 6:30 pm. In other words, the actual time they arrived at the lake was nearer 6:50 pm. If this was the Zodiac Killer after the attack on Bryan Hartnell and Cecelia Shepard, it may explain the "red coloring" on the shirt.
Dr. Clifton Rayfield had driven from Cypress Way, Los Gatos, California - so he would have traveled northwards along Knoxville Road. Had Zodiac's vehicle been parked further north, just out of view, then this would explain why Dr. Rayfied and son claimed they "had not observed a vehicle parked in the area of their car". The 6:50 pm sighting would have put greater pressure on the already strained timeline, of Zodiac leaving this area and committing any subsequent attack on Bryan Hartnell and Cecelia Shepard south of this location. This coupled with the fact Zodiac wrote 6:30 pm on the Karmann Ghia, strengthens Dr. Rayfield's initial assumption, when he stated, "I didn’t realize 'Zodiac' came upon us just before he stabbed the young couple. I sort of assumed I saw him making his getaway".
If this was the Zodiac Killer, then he was most certainly making his getaway, thereby bolstering the argument that he had never parked alongside the Karmann Ghia of Bryan Hartnell that evening. If it wasn't the Zodiac Killer spotted by Dr. Rayfield & Son, then what you have just read is inconsequential.
LAKE BERRYESSA-NORTH OF THE CRIME SCENE [PT1]