In the Benicia Herald online this is confirmed "Bidou and his partner had served a warrant on a Lake Herman Road cabin Dec 20th 1968 and were on their way to deposit some marijuana in the police department's evidence locker when they were dispatched back to Lake Herman Road." http://beniciaheraldonline.com/citizens-police-academy-signs-of-the-zodiac/
In True Crime with Aphrodite Jones (2010) he states at 11:58 into the video "And you can see she is dead and the bloods still fresh, her heart was still pumping the blood out when we got here."
By all accounts it appeared Pierre Bidou responded pretty quickly to the crime scene and was one of earliest officers at the Lake Herman Road turnout. But there is one very big problem when we look at the timeline of Frank Gasser, Robert Connelly, Peggy and Homer Your, Stella Borges and James Owen.

Pierre Bidou stated he passed the turnout on the way to the Benicia Police Department, his headlights illuminating the turnout and nobody was observed. It takes approximately 8 minutes to arrive at the Benicia Police Department from this location traveling at 30 mph- at which point he receives the dispatcher's call of a possible murder. Pierre Bidou by all accounts had to have passed the scene before the murders, yet how can 8 minutes, or even 10 minutes later, a possible double murder have been reported. The timeline of the above eyewitnesses is 15-20 minutes. In other words, after Pierre Bidou had passed the turnout David Faraday and Betty Lou Jensen would have had to park up, been spotted by six eyewitnesses over a period of 15-20 minutes, before and after the murders, before Stella Borges raced off to notify Officer Daniel Pitta a further 3 to 4 minutes later. He was the first officer to have been informed of the crime. This means 18 to 23 minutes had elapsed from the first eyewitnesses spotting David Faraday's Rambler, to the reporting of the crime to Officer Daniel Pitta. So how could Pierre Bidou have been notified as he pulled into the Benicia Police Department just 8 to 10 minutes later after passing an empty turnout and stating "We had left and were heading back to the police department to put the marijuana into evidence and as we drove by we didn't see or observe anybody in that area." There is simply not enough time for all these eyewitnesses to have observed and done what they said they did, and for both David Faraday and Betty Lou Jensen to have been killed in approximately 8 minutes.
Furthermore, considering the slender timeline- if Pierre Bidou had passed the turnout and spotted nothing- then for the Zodiac to have entered the turnout shortly after David Faraday and Betty Lou Jensen had arrived, committed the crime and left without being seen, would suggest he not only arrived from the Vallejo area but had returned that way afterwards- any other scenario would have him passing Pierre Bidou as he was traveling towards Benicia and this was not mentioned by Pierre Bidou. However, had the Zodiac chosen to turn left and head towards Vallejo after the murders, he would have passed Stella Borges along Lake Herman Road, and she reported passing no other vehicles en route to Benicia. Again the timeline breaks down.

Who sent this 'crank call'- it certainly sounds from reading between the lines, that this wasn't an official police radio dispatch relayed from Officer Daniel Pitta. Could it have been an early Zodiac phone call? The only other two people to have known about the Lake Herman Road crime scene at approximately 11.18-11.23 pm was Stella Borges and Officer Daniel Pitta. However, if Officer Pitta had called in the crime, it would have been an official radio message, not a crank call- possibly indicating a third party was aware of the scene at Lake Herman Road. So either somebody else of innocent persuasion had also passed the scene near to the timeline of Stella Borges, or the Zodiac himself had called it in.
Finally, in the True Crime video with Aphrodite Jones (2010) https://youtu.be/TFp9s3cwkms?t=11m9s Pierre Bidou twice mentioned David Faraday being inside the car, at 11:17 and 11:45 into the video. He stated "The young man was still in the car" and "you see the male in the car still breathing." In the https://beniciaherald.wordpress.com/the-zodiac-case/ article it stated "Inside the car, the officers found a boy in the passenger’s seat who appeared as if “he was trying to get out” of the car. Bidou remembers seeing the shattered glass of the car window, pierced by a bullet. More poignantly, he also remembers that the boy was still breathing." Additionally, on the 'Richard Gaikowski-The Case of the Zodiac Killer' video, we get a further example at 13:22 where Pierre Bidou stated "The male was still halfway in the vehicle and he was showing signs of breathing." https://youtu.be/vdVJH1OVk-Q?t=13m22s. I suppose we will have to put these four examples down to a slip of the tongue.