Here we will take a closer look at the blooded fingerprints left on the Paul Stine taxicab in Presidio Heights on October 11th 1969, and see if they can reveal anything about the unfolding events that night. 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 blooded 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 blooded 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.

There is a possible explanation for the blooded prints shown on the left image, regarding a Washington and Maple murder, but here we shall stick with the widely held belief that the killing took place close to the intersection of Washington and Cherry.
The placement of the blooded print discovered on the front exterior passenger door handle effectively negates 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 exits the right rear passenger door with the gun still in his hand, or while putting it away, he would use his left hand to open it and close it, which is why no blooded prints were found on the right rear inner passenger door handle, or the exterior of the right rear passenger door. The Zodiac Killer was described by the three teenagers wiping down the front passenger door. It is likely he didn't thoroughly remove the blooded fingerprints, evident by their discovery.
The placement of the blooded print discovered on the front exterior passenger door handle effectively negates 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 exits the right rear passenger door with the gun still in his hand, or while putting it away, he would use his left hand to open it and close it, which is why no blooded prints were found on the right rear inner passenger door handle, or the exterior of the right rear passenger door. The Zodiac Killer was described by the three teenagers wiping down the front passenger door. It is likely he didn't thoroughly remove the blooded fingerprints, evident by their discovery.

The Robbins teenagers gave a more detailed account of the night's events in a later interview, one partially corroborated by Armond Pelissetti, who discovered the teenagers out in the street. They stated a crucial fact, that fits the evidence and it makes perfect sense: "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."
If 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. Had he then took 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), then left the scene, why should he have ever touched the panel between the driver side door and left rear passenger door with his blooded hands. This was the version in the police report, and simply doesn't explain why blooded prints were discovered on this dividing panel.
But the more expansive version given by the Robbins kids explains this anomaly perfectly.
If 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. Had he then took 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), then left the scene, why should he have ever touched the panel between the driver side door and left rear passenger door with his blooded hands. This was the version in the police report, and simply doesn't explain why blooded prints were discovered on this dividing panel.
But the more expansive version given by the Robbins kids explains this anomaly perfectly.

The teenagers stated that the killer twice attempted to reposition Paul Stine upright behind the steering wheel. The most logical reason for this, could be argued, that the killer unaware he had been observed by the teenagers, was buying time for his escape on foot. A taxicab driver sitting behind the steering wheel of his vehicle in fairly dim conditions at 10.00 pm at night, was unlikely to attract the attention of the casual pedestrian or passing motorist, with a fleeting glance, but a prostrate driver sprawled across the taxicab seat may have drawn attention to the crime, and resultant contacting of police. In the absence of many alternatives for this action, it may seem the most logical.
The teenagers clearly stated, that after he rounded the taxicab, he opened the driver side door, likely using his left hand (for reasons given above). But to pull Paul Stine back into an upright position he needs stability and leverage. This would be attained by bracing your right hand on the dividing panel between the driver side and rear door, to pull Paul Stine upright using your left hand. Once finished, the Zodiac Killer closed the driver side door and wiped the door handle. This handle may very well have received blood transfer from the killer's left hand when he initially opened it, after all he likely used it when tearing the shirt. Nevertheless, he either wiped it down thoroughly before he left the scene, or enough so that blooded fingerprints, if deposited, were not present. However he made a crucial mistake. By concentrating on the door handles, he overlooked the blooded fingerprints deposited by his right hand on the dividing panel. This was detailed in the Robert Graysmith book Zodiac: "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". He exited up 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 with his head coming to rest in the front passenger floorboard, where Armond Pelissetti would ultimately discover the stricken taxicab driver.
The teenagers clearly stated, that after he rounded the taxicab, he opened the driver side door, likely using his left hand (for reasons given above). But to pull Paul Stine back into an upright position he needs stability and leverage. This would be attained by bracing your right hand on the dividing panel between the driver side and rear door, to pull Paul Stine upright using your left hand. Once finished, the Zodiac Killer closed the driver side door and wiped the door handle. This handle may very well have received blood transfer from the killer's left hand when he initially opened it, after all he likely used it when tearing the shirt. Nevertheless, he either wiped it down thoroughly before he left the scene, or enough so that blooded fingerprints, if deposited, were not present. However he made a crucial mistake. By concentrating on the door handles, he overlooked the blooded fingerprints deposited by his right hand on the dividing panel. This was detailed in the Robert Graysmith book Zodiac: "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". He exited up 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 with his head coming to rest in the front passenger floorboard, where Armond Pelissetti would ultimately discover the stricken taxicab driver.