
Earlier on in the day, three young women, students of Pacific Union College, parked their vehicle two miles north of the A & W Root Beer stand (5100 Knoxville Road). As they left their vehicle to go sunbathing, a white male, driving a silver or light blue Chevrolet 2-door sedan with California plates pulled up to the rear of their car, bumper to bumper, yet remained inside his vehicle. This man would seemingly remain in his vehicle for approximately 30 minutes before they spotted him again, observing them from about 40 to 50 feet away while they were sunbathing - and each time they looked at him he evaded eye contact thus drawing suspicion.
He was described as being between 28 and 40 years, 200-225 pounds, 6 feet tall, styled black hair, with rounded eyes and thin lips. He was good looking, with a muscular or stocky build, wearing dark blue or black pleated slacks and a dark pullover shirt. He remained observing them, by their accounts, for approximately 30 to 45 minutes. About two hours later, Bryan Hartnell described his attacker as having dark brown hair, 225-250 lbs in weight and 5'8'' to 5'10'' in height, but admitted he was a bad judge of height because he was so tall. He wore a dark blue windbreaker and dark blue or black pleated pants. Bryan Hartnell noted the assailant's greasy hair visible by the eyelets of the hood, suggesting a longer hairstyle, and not inconsistent with the drawing generated from the observations of the three women, with a swept back coiffured hairstyle.

In Zodiac Unmasked by Robert Graysmith, David Rayfield stated "I saw 'Zodiac' at a distance of about one hundred yards, so I wouldn’t be able to comment on his face. He was walking along the hillside about halfway between the road and the lake. But I remember him as being a stockier person. He wasn’t nimble when he was walking. And when he turned to walk away he wasn’t like a smooth, athletic person. To me he seemed a little overweight and on the clumsier side. Not having followed the story or ever having been re-interviewed by the police, 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. I’ll tell you one thing, he didn’t like the fact I was carrying a gun. He turns and looks at me and my gun (which with its scope was pretty intimidating) for probably five, six seconds, and then turned and went up the hill up in a southerly direction. I said to myself, ‘That was funny. This guy wasn’t carrying a fishing pole. There’s no camping equipment. There’s no gun. What’s he doing out here?"
Napa County Sheriff's Department detective Ken Narlow would add "The kid had a .22 rifle, and 'Zodiac' came down within one hundred yards of them across an inlet. The kid saw the guy over there and he was wearing the blue windbreaker jacket. But evidently this wasn’t what he was looking for because it was a father-and-son deal. So the killer went a quarter mile up this road, went back up to the road, and evidently came down the road this way and saw this single car parked here, and then pulled in behind it. Rayfield and his son both stated that they had not observed a vehicle parked in the area of their car, and had only noticed the subject at a distance of approximately one hundred yards. Rayfield did report that there was a man with two young boys in the area shooting BB guns, but didn’t know whether or not they saw the subject. “I think their time was off a little bit ’cause I think Rayfield actually saw the Zodiac killer just prior to him going south four-fifths of a mile to where Shephard and Hartnell had their car parked. It sure looks like he stumbled on them and had not followed them. I’m convinced that Zodiac was just stalking any singular parked cars along the route. And that’s why he stopped when he saw Rayfield’s car there. When he saw the father and son and they saw him, he decided to go back up to his car. Then he drove down the road a little ways and saw the white Karmann Ghia. Then he came down here and saw a boy and a girl laying on this blanket under this oak tree, and this is what his game was, to kill the boy and the girl. This is why he struck here and not further up the road".

The reason for believing this sighting could have been after the attack on Bryan Hartnell and Cecelia Shepard are threefold.
In Zodiac Unmasked, Detective Ken Narlow revealed "Dr. Clifton Rayfield, an ophthalmologist, and his son, David, had parked their car four-fifths of a mile further up the road from Hartnell’s Karmann Ghia. Rayfield reported to me that at approximately 6:30 P.M. he and his son had parked their vehicle north of Park Headquarters . . . in the general area of the crime scene and walked down toward the beach. While en route Rayfield observed a WMA described as five feet ten inches, heavy build, wearing dark trousers and a long-sleeved dark shirt with red coloring". Was this "red coloring" actually blood, with the Zodiac Killer heading back to his car parked nearby, likely just beyond the Rayfield vehicle. Had this been 6:50 to 6:55 pm, then the 45-50 minute journey time from Lake Berryessa to the 1231 Main Street, Napa payphone, would have placed him there at exactly 7:40 pm and the time of the call to police dispatcher David Slaight. Had the Zodiac Killer departed Lake Berryessa at 6:30 pm it would have left at least 20 minutes unaccounted for. The 20 minute walk to his vehicle from Bryan Hartnell's Karmann Ghia to his vehicle, just beyond the Rayfield sighting, fills in this time period. This period of walking may also account for the discrepancy in Zodiac's phone call, where he overestimated his distances by 1.3 miles: "I want to report a murder, no, a double murder. They are two miles north of Park Headquarters. They were in a white Volkswagen Karmann Ghia" and after a brief pause uttered the words "I'm the one that did it".
Earlier, the three women described the man wearing a "white belt around his back" or possibly "a white T-shirt hanging out". It has been considered that bearing in mind the man was a distance away, this could have been the white clothesline, described later by Bryan Hartnell. Then we have the "long-sleeved dark shirt with red coloring". But were the two sightings connected - effectively ruling out the idea Zodiac parked alongside Bryan Hartnell's vehicle before the attack - and suggest the Zodiac Killer was actually trolling the hillside on foot looking for single vehicles and vulnerable targets, and his vehicle was actually parked just over four-fifths of a mile north of the crime scene.
LAKE BERRYESSA-NORTH OF THE CRIME SCENE [PT2]
http://murders.ru/zodiac%20unmasked.pdf