In total, thirty latent fingerprints, three palm prints and one partial of value were retrieved from the taxicab. The latent prints that exhibited traces of blood were believed to have been deposited by the killer. The two key areas where bloody fingerprints were retrieved, were the exterior front passenger side door handle and the dividing panel between the driver side door and the left rear passenger door, just above half way. The FBI report only stated that the murderer was the likely donor of both bloodied latent prints, probably because they likely contained different digit impressions, or one was lacking detail. There is very good reason to believe both impressions were from the killer, which we will explain later. In the photographs on various sites these two prints are circled with a red pen.
The placement of the bloody print discovered on the front exterior passenger door handle challenges the premise of a passenger who rode in the front seat of Paul Stine's taxicab. Had this been the case, after removing the piece of shirt and exiting the front passenger side door, there would be no need to shut the door using the exterior door handle, but there would be every reason to wipe it down, as observed by the three teenagers. This is because the natural way to open the front passenger door after exiting the right rear of the taxicab would be to use your right hand. When opening a right-sided door it is more natural to use your right hand. Standing by a right-sided door and using your left hand would bring the door into your midriff.
When the killer shot Paul Stine he likely received a fine mist of back spatter to his right hand. If he then exited the right rear passenger door with the gun still in his hand, or while putting it away, he would have used his left hand to open it and close it. This may explain why no bloody prints were found on the right rear inner or outer passenger door handle. The Zodiac Killer was described by the three teenagers to be wiping down the front passenger door. It is likely he didn't thoroughly remove the bloody fingerprints, evident by their discovery.
They recounted their observations that night - observations that marry perfectly with evidence retrieved from the taxicab:
"At this time, Lindsey went downstairs to get a better look at what was happening, while one of the kids upstairs called the police. Downstairs, the lights were off, so Lindsey knew he could not be seen from the outside. He got close to the window and watched his actions. He was shortly joined by Rebecca. They both watched and observed in silence as Zodiac pushed the driver to an upright position behind the steering wheel, exited the car and walked around the rear of the car and opened the driver's door. Stine had fallen over onto the seat and Zodiac pulled him back up into the seated position and had some difficulty keeping him upright. Once upright, he was seen to have a rag, or something like a handkerchief and began to wipe down the door area and leaning over the driver, part of the dashboard. When he was finished, Zodiac calmly walked to Cherry St. and walked north."
The Zodiac Killer had entered the taxicab at the theater district, shot Paul Stine at the intersection of Washington and Cherry, exited the right rear passenger door and entered the front passenger door. He then removed the shirt piece, exited the taxicab and proceeded around to the exterior driver side door to wipe it down, presumably with his dominant right hand (or not). He then left the scene via Cherry Street. Where in this sequence of events should he had ever touched the panel between the driver side door and left rear passenger door with his bloody hands? This was the version in the police report, and fails to account for the bloody fingerprints discovered on the dividing panel of the taxicab.
But the more expansive version given by the Robbins kids explains this anomaly perfectly.
The teenagers clearly stated, that after he rounded the taxicab, the subject then opened the driver side door, likely using his left hand (for reasons given above). He then attempted to pull the stricken taxicab driver back into an upright position. But to perform this action he needed stability and leverage. This would be achieved by bracing your right hand on the dividing panel between the driver side and left rear door in order to pull Paul Stine upright using your left hand. Once finished, the Zodiac Killer closed the driver side door and wiped down the door handle.
However, he made a crucial mistake. By concentrating on the door handles, he may have inadvertently overlooked the bloody fingerprints deposited by his right hand on the dividing panel. This was detailed in 'Zodiac' by Robert Graysmith : "At one point he opened up the driver's door and leaned forward to wipe off the area of the dashboard again. To steady himself, he leaned his right hand on the rail separating the front and rear windows. The fragment of cloth was still in his left hand. Then he closed the door and walked away".
The Zodiac Killer then exited north along Cherry Street and into the night. Paul Stine's body at some point, aided by the camber of the road, fell back across the front passenger seat - his head coming to rest on the front passenger floorboard, where Armond Pelissetti would ultimately discover the stricken taxicab driver just a few minutes later.