Is there anyway to find a definitive answer nearly 50 years later, well the short answer is no, but by reading through the detail and listening to accounts of Armond Pelissetti, the first responding officer that night and Donald Fouke being interviewed on 'This is the Zodiac Speaking' (2007) and the 'Crimes of the Century' (1989) documentaries, we can say it is extremely likely a conversation between the police and the killer did occur. Of course memories get blurred over time and this can be understood, however there are definite red flags of such inconsistency, one finds it difficult to explain away
Donald Fouke on the other hand was at the same time (9.55 pm) making his approach to the crime scene, he had just passed Washington Street so his quickest and most direct route was north to Jackson Street, west along Jackson Street to Cherry Street and then south to the crime scene and this is exactly what he did. En route mind he noticed a white male on the north side of Jackson Street as he approached Maple Street, however believing he was looking for a black negro adult he slowed down as he passed the man but failed to stop or question him and then sped off up Jackson Street, before turning southbound into Cherry, where he stated in the 'This is the Zodiac Speaking' documentary he bumped into Armond Pelissetti who was cautiously scanning Cherry Street. It is then crucially that Donald Fouke said "He stopped us and said that he was looking for the white male that had just gone down the street. There was a little conversation about what the initial description was and he said no he was a white male, I then used a slang term and said oh that was the suspect." Clearly Donald Fouke was still under the impression he was on the lookout for a black male until he was corrected.
He stated "We proceeded on Jackson Street towards Arguello continuing our search, as we arrived at Arguello Street the description of the suspect was changed to a white male adult, believing this suspect was possibly the one involved in the shooting we entered the Presidio of San Francisco and conducted a search on West Pacific Avenue, the opposite side of the wall and the last direction we observed the suspect going, we did not find the suspect."
Clearly the two accounts differ markedly and from the standpoint of common sense turning southbound on Cherry seemed the correct course of action, after all he was responding to the crime scene at Washington and Cherry and Donald Fouke was unaware at this point in time that Armond Pelissetti has responded to the crime scene before him, so what was he doing as he claimed in the 'Crimes of the Century' documentary, heading towards Arguello Boulevard and West Pacific Avenue, away from the crime scene. Remember what the Zodiac claimed in the Bus Bomb Letter on November 9th "p.s. 2 cops pulled a goof abot 3 min after I left the cab. I was walking down the hill to the park when this cop car pulled up + one of them called me over + asked if I saw anyone acting suspicious or strange in the last 5 to 10 min + I said yes there was this man who was runnig by waveing a gun & the cops peeled rubber + went around the corner as I directed them."
In other words the only reason for Donald Fouke and Eric Zelms to have been heading towards Arguello Boulevard and around the corner into West Pacific Avenue, away from the crime scene, is if Zodiac directed them there and they were looking for a man 'running and waving a gun'.
So the question to ask is, what was Donald Fouke doing with this extra time, of which there could be at least two minutes.
If he claimed he turned straight into Cherry Street as he stated in 'This is the Zodiac Speaking' documentary, then he would have to have stopped and talked to the white male suspect in Jackson Street for possibly 2 minutes to allow for this and based on the dialogue given by Zodiac in the Bus Bomb Letter it was more likely a matter of seconds rather than minutes, so this scenario is unlikely. However if he had briefly talked to the Zodiac and had been directed to Arguello Boulevard and then had conducted a brief sweep of West Pacific Avenue, before returning to Cherry Street to meet Armond Pelissetti, this 2+ minutes are accounted for easily, meaning the 'Crimes of the Century' documentary is truer to the unfolding events of October 11th 1969 and not his later account in 'This is the Zodiac Speaking' which does not conform to the timeline, in fact it simply is not possible whichever way you twist it.
A big thanks to Alex Lewis for all his help on this subject.