and  When the killer opened fire on Darlene Ferrin, Michael Mageau turned away, lowering his body from the barrel of the gun. After the initial two shots, the killer then turned the gun on Michael. He was struck twice, once in the neck (facial area) and once in the shoulder, before propelling himself to the rear of the vehicle in an attempt to escape the barrage. Both of these bullets exited his body, striking Darlene Ferrin in the torso. The two bullets lost momentum after passing through Mageau and had reduced velocity when they entered Darlene Ferrin, thereby remaining in her body. #1 was removed from the right second rib. #2 was removed from the seventh and eighth rib left. These were the only two bullets recovered from Darlene Ferrin at autopsy.
A letter was received by the San Francisco Examiner on July 4th 1969 in which Zodiac described 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". Michael described these two shots in the police report: "He heard a muffled sound and felt a pain in his back and his neck area. He states he heard some more muffled sounds, sounding like a gun with a silencer on it, and felt pains in his body, his back and around his neck. States he tried to climb over the back seat to get away from the shooting". The killer had now fired 4 shots. Michael Mageau had been struck twice, and Darlene Ferrin had received 6 entry wounds and 4 exit wounds.
 and  The Zodiac Killer returned to the passenger side window and leaned into the vehicle, and extended his arm over the front seats to fire 2 more shots at Michael Mageau, striking him in the thigh and hip. These two expended casings fell onto the rear floorboard. The Zodiac described this as "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".
 and  The killer then turned back to Darlene Ferrin, firing off the final 2 shots. Both of these bullets struck her torso and exited on through. She had now received a devastating 9 entry wounds and 7 exit wounds, as described in the autopsy. Two of the final four shots were likely aimed at Michael Mageau first, as he explained to officers that he "could not tell if he meant to yell at the subject or if he just yelled from pain, but he let out some type of yell. At this time, the subject apparently hearing him, came back to the car and shot Michael two more times, once in the back and once in the left leg. States the subject then turned the gun on Dea and shot her twice more". Michael Mageau had actually been struck in the thigh and hip. The killer then retreated into the night. Just under 40 minutes later, the Zodiac would announce himself to the world in a chilling phone call to police dispatcher Nancy Slover.
The first shot traveled as shown, creating 2 entry and exit wounds. The second shot is more difficult to explain.
In order to make any sense of this wound pattern, imagine that we need to make these four circles approximately line up.
The white arrow would depict how Darlene Ferrin's arm came across her body, placing it at extremely acute angle to the shooter (the act of turning away). The four circles are now lined up, producing 2 entry and exit wounds. The bullet entered 5 1/2 inches above the right elbow and exited 1 1/4 inches distal to the right elbow. It then entered 3 1/4 inches above the left elbow and exited the opposite side.
The first shot didn't necessarily strike Darlene Ferrin while she was holding the steering wheel, but it is a strong possibility. The right forearm was struck 3 1/2 inches above the wrist, entering the left forearm 2 inches above the wrist.
This however, is only one possible explanation. If you have any comments regarding this analysis, please let me know.