Seven bullet casings were found to the right side of the car (not marked on the police report). Two bullet casings were discovered on the rear floorboard of the Corvair, because the killer had leaned into the vehicle to take aim at Michael Mageau who had sought refuge there. When investigators arrived they found this:
There is a strong possibility she prepared the Corvair for departure, not fully confident that the man approaching the passenger side of her vehicle was law enforcement. She may have released the handbrake while in neutral, turned the engine on, depressed the clutch pedal and placed the Corvair into 1st gear as a precautionary measure, while having her hands readied on the steering wheel. The approaching Zodiac Killer, fearing the driver may have been preparing to drive away, opened fire the instant he reached the passenger side window of the vehicle. He would have targetted Darlene Ferrin first, as she was the person who could foil his successful attack. She is immediately struck by two bullets in the arms, causing four entry and four exit wounds. Her foot disengages from the clutch pedal and the vehicle stalls. Responding officers would find her Corvair with the handbrake released, ignition on and transmission in 1st gear.
There is every chance that Darlene Ferrin was spooked by the approach of a vehicle behind them in the Blue Rock Springs parking lot and made the neccessary steps for a quick exit from the scene. The notion that both Michael Mageau and Darlene Ferrin just sat passively in the Corvair readying their identification to display to the approaching man, is not backed up by the ballistics evidence or the condition her vehicle was found in by responding officers that morning. Darlene Ferrin's preparatory steps suggest she was within a whisker of driving away that night, and the Zodiac Killer was fully aware of that possibility. Had this not been the case, then the events of Blue Rock Springs may have unfolded exactly as they did at Lake Herman Road, only six-and-a--half months earlier.
The statement of George Bryant (caretaker's son), who lived only 800 feet from the parking lot, stated that he heard shots at about midnight. Jerry, Roger and Debbie likely arrived at the parking lot at approximately 12:04 am, with the Zodiac Killer having left the crime scene only a matter of minutes earlier. They would have departed the parking lot at 12:05 am for the four minute journey to 938 Castlewood Drive, so as to place the call to police about a minute later, at 12:10 am. This suggests that despite Darlene Ferrin having sustained nine entry wounds and seven exit wounds, which included four entry and exit wounds to her wrists and arms, she had the presence of mind to valiantly switch on her main lights and left blinker lights to attract attention to both her and Michael's desperate plight as Debbie's vehicle stopped on the road. This act may have encouraged Debbie to reposition her vehicle on the road and shine her main beams toward the Corvair, ultimately highlighting the hapless Michael Mageau in the darkness of the parking lot. It is without doubt the actions of Darlene Ferrin helped save the life of Michael Mageau, but unfortunately, actions that would come too late to save her.