One thing may help us uncover the order of events that night, that of the ballistics and Darlene Ferrin's autopsy report, which has some unusual details to untangle. Here is a section of that report, indicating that Darlene Ferrin had nine entry wounds and seven exit wounds. An extremely high number considering Michael Mageau was shot four times. Some bullets of course passed through both victims, but it still takes some explaining. The report describes two entry wounds on her right arm and two entry wounds on her left arm, with two bullets recovered internally.
On page 17 it states 'After both victims were taken to the Kaiser Hospital, writer checked the area for any spent bullets, upon checking the Corvair writer observed what appeared a bullet hole in the left door panel.'
Hardly surprising if multiple shots were fired through the right side window.
Then we have one bullet described as having been recovered from Michael Mageau's thigh. Michael was struck in the neck, hip, left thigh and shoulder.
This is important because it leaves only seven shots left to create nine entry wounds and seven exit wounds detailed in Darlene Ferrin's autopsy. Two bullets remained inside Darlene Ferrin, so didn't produce any exit wounds. Now we have only five bullets remaining to create seven exit wounds, two of which struck Michael Mageau in the front seat.
Darlene Ferrin it has been surmised was shot in the arms while gripping the steering wheel, 2 bullets that struck her right arm, exited her right arm and struck her left arm, which they exited also, producing 4 entry and 4 exit wounds.
The 2 bullets that struck Mageau on the front seat would have lost velocity, entering Darlene Ferrin but not exiting her body. These were the 2 bullets found internally at her autopsy. The other 3 bullets that struck Darlene Ferrin's torso directly produced 3 exit wounds (add this to the 4 exit wounds on her arms, gives us the total of 7 exit wounds).
She had 4 entry wounds in her arms from 2 bullets, she had 2 entry wounds via Michael Mageau (the lodged bullets at autopsy) in her torso and 3 entry wounds that struck her directly (one during the initial barrage and two when Zodiac returned).
In total giving us 9 entry wounds.
Michael Mageau was targeted directly 4 times, Darlene Ferrin was targeted directly 5 times (2 at her arms, 3 at her torso).
One bullet, the one discovered in the left panel of the driver side door, therefore was the only bullet that exited her torso, because the other 2 were retrieved internally at autopsy.
The strange thing about this scenario is the conception many believe of how the shooting unfolded. That Michael Mageau was targeted first, yet Darlene Ferrin was still likely gripping the steering wheel with both arms even by the time of the fourth shot, to facilitate the through and through wounds to both her arms (see foot of article). Bearing in mind the vehicle was in first gear, with the hand brake off, had she attempted to prepare the vehicle to drive away, valiantly gripping the steering wheel as Michael was being shot.
A letter was received by the San Francisco Examiner on July 4th 1969 in which Zodiac describes his attack "On the 4th of July I did not open the car door. The window was rolled down all ready. The boy was origionaly sitting in the front seat when I began fireing. When I fired the first shot at his head, he leaped backwards at the same time, thus spoiling my aim. He ended up on the back seat then the floor in back thashing out very violently with his legs; that's how I shot him in the knee. "
One possible order of events and by no means the only one, is that Zodiac targeted Darlene Ferrin first, striking both her arms with 2 shots, after all she was the driver and means of escape. He quickly turns the gun onto Michael Mageau, striking him in the neck and rear shoulder as he is turning away from the gun. He then fires a further shot into Darlene Ferrin's torso, as Michael hurls himself backwards into the rear seats. Five shots have now been fired. Zodiac walks away, then returns to shoot Michael in the rear seat twice (hip and thigh), then Darlene twice more into her torso, before leaving the scene.
Another plausible order of events derives from the words of Michael Mageau in the police report (see foot of article). Michael is searching for his ID as the assailant fires two shots at his neck and shoulder. Darlene Ferrin could have sensed danger early on, having prepared the vehicle for a quick exit, disengaging the hand brake and setting the transmission. Her hands could already be braced on the steering wheel or she could have placed them there when the assailant started shooting Michael Mageau. She may very well have reached for the ignition. But whatever the case, her arms were aligned to receive the injuries detailed at autopsy. Once she was struck in the arms, she then turned away in a defensive motion and was struck again in her right rear. Michael meanwhile has leapt into the back seat. The rest follows the same pattern as above- Zodiac leaves, returns, and delivers the final 4 shots.
This article explains the movements of the killer that night, his account in the 'Debut of Zodiac' letter, the nine shots fired and the nine entry wounds and seven exit wounds detailed in Darlene Ferrin's autopsy report.
What the autopsy does, is paint a picture of the sequence of events that night, and that Michael Mageau's version of catapulting himself backwards to the rear seats of the Corvair, to escape the initial barrage, is supported by all the ballistics evidence, but what the autopsy results won't reveal about the events that night, is why.
Department of Justice (DOJ) report.