THE SILENT MURDER AT PRESIDIO HEIGHTS

After the brutal execution of Paul Stine at Presidio Heights on October 11th 1969, the question has always remained, which route did the Zodiac Killer take after he was last seen walking away from the crime scene northbound along Cherry Street. This is where the facts cease and the speculation begins, so let us start with what we do know. The Zodiac Killer was spotted from the upstairs window of a house across the street, approximately 50-60 feet from the murder scene by three teenagers.
The killer appeared to be wiping down areas of the taxicab, from both inside and outside, but crucially the witnesses reported hearing no gunshot. The fare was logged for Washington and Maple Street but the taxicab had traveled one block further to the corner of Washington and Cherry Streets. 
More importantly, two days after the callous murder, the Zodiac Killer mailed a letter to the San Francisco Chronicle containing a cut section of Paul Stine's shirt, leaving law enforcement in no doubt that the murderer of four young people, had indeed brought his reign of terror to the midst of San Francisco - but that was not all.
The Zodiac Killer began his letter with the words "I am the murderer of the taxi driver over by Washington St + Maple St last night, to prove this here is a blood stained piece of his shirt. I am the same man who did in the people in the north bay area". The killer was even claiming to have committed the crime of murder, at Washington and Maple, not at Washington and Cherry where he was ultimately observed leaving the taxicab and heading north up Cherry Street. This would clearly explain the absence of any gunshot heard by the three teenagers - because there wasn't one. 

The reason for believing the actual murder of Paul Stine took place at Washington and Maple Street can be explained by tracing the killer's footsteps once he left the taxicab, headed along Cherry Street and what he did next.
It takes a matter of 60 seconds to travel up Cherry Street, before you head east onto Jackson Street. Why though, would the killer have to head east along Jackson Street? Because if his intention was to kill Paul Stine at the Washington and Maple intersection, then logically he would have left his getaway vehicle somewhere north along Maple Street. not too close to warrant identification, but not too far to risk being apprehended.
This would explain his actions of heading north from the area where the taxicab came to rest, up Cherry Street and backtracking east along Jackson Street, thereby 

heading back to his getaway vehicle, somewhere at the top of Maple Street. It may be the case his vehicle was parked somewhere along Jackson Street, West Pacific Avenue or by the eastern edge of Presidio Park, but ideally the least walking he could afford himself, the better.
When responding officers Donald Fouke and Eric Zelms steered their patrol car into Jackson Street, they noticed a white male, described later, as 35-45 years, 5'10" in height, 180-200 lbs, barrel chested, with light colored hair, who appeared to be in no hurry - in what Officer Donald Fouke described as a shuffling lope, bent forward with his head down. He also remembered the man entering the stairwell of a house, thought to be 3712 Jackson Street. But was this the Zodiac Killer. 

There may be a strong possibility, that indeed, this was our killer. But for one reason only. He was on the wrong side of the street.
Why was the killer walking on the north or right sidewalk, as viewed by the patrol car.
Any responding police vehicles in the vicinity, immediately after the call was received, would have been heading towards the crime scene at Washington and Cherry Street, not away. So why does the killer head up Cherry Street and cross over the road to the 

north sidewalk of Jackson Street, placing himself in closer proximity to approaching police vehicles and the glare of headlights. Any blood transfer on his person or clothing would be more likely to be spotted from a patrol car on this side of the road.
One reason the murderer of Paul Stine would have contemplated being present on this side of the street, would be if he had killed the taxicab driver at Washington and Maple, not Washington and Cherry. But why?
The absence of a gunshot being heard by the three teenagers has been speculated on before, and a great article can be found here at http://www.zodiackillerfacts.com/blog/mysteryquest-paul-holes-and-the-murder-of-paul-stine, explaining a possible alternative to the widely held view. The killer draws his gun just as Paul Stine is starting to pull over at Washington and Maple, and either a brief struggle ensued, or the taxicab driver is killed immediately with a single shot to the right side of his head. But either way, Paul Stine's foot slips off the brake pedal and the killer has to react immediately by entering over to the front passenger side of the taxicab, leaning or pushing Paul Stine's lifeless body over towards the driver side door, so he can gain some form of limited control over the foot pedals and steering wheel. He then coasts the taxicab away from Washington and Maple - and the sound of the gunshot -  to the next intersection at Washington and Cherry, where the taxicab is brought to its final resting place. There has also been speculation that the murderer traveled in the front passenger side of the taxicab during the journey, but either way, if Paul Stine had been murdered at Washington and Maple as the Zodiac Killer himself claimed, then for one entire block it was possible the killer was pushing left against Paul Stine's body as he tried to regain some form of control.
The blood loss exhibited at the scene would have meant the Zodiac Killer's left side would have received the majority of the blood transfer, as he leaned against Paul Stine in commandeering the vehicle. This would explain why the killer was wiping down various parts of the front side of the taxicab. If he had remained in the rear of the taxicab throughout, this would have been unnecessary.  

This now would explain his actions, after he left the scene and rounded the corner of Cherry Street. Being aware that his left side had received the majority of the blood transfer, he either immediately crossed to the left side of Cherry Street, or knowing that he possibly had 60 seconds of 'free' time, waited until he reached Jackson Street before crossing onto the north sidewalk. This would keep his left side facing away from the roadside and any passing vehicles. He could, at the very least, have angled himself to the left side as any cars or police vehicles approached, without drawing too much attention.
A killer turning away fully to the left may have raised suspicion  - unless entering the stairwell of 3712 Jackson Street is your next best option, to fully conceal the blood apparent on one side of your clothing.

Of course, if the killer had exited the crime scene and traveled on the left side of Cherry or Jackson Street, as viewed by the approaching patrol car, the left part of his body would have been exposed to the full glare of passing vehicles. Any motion to turn into a residence on that side of the street would again expose the blood on the left side of his attire. If he had turned to face into the street to conceal his left side, his face would be in full view, so any description passed out would once more draw too much unwanted attention.
This may explain the reason why the killer chose to walk on the north side of Jackson Street, in closer proximity to oncoming traffic and fly in the face of the rational choice - of staying on the south side of the street.
The killer claimed two days later in his letter the the San Francisco Chronicle, that he was hiding in the Presidio Park, but this proclamation has been widely discredited by some, due to the fact sniffer dogs were employed in the search, and anybody hiding in the park covered in blood, would have been apprehended fairly quickly. 
But one thing the Zodiac Killer did say, that was probably true, was "I am the murderer of the taxi driver over by Washington St + Maple St last night" - and the real reason, why he was, where he was, when Donald Fouke and Eric Zelms entered Jackson Street on that fateful October night back in 1969.