Just before midnight on July 4, 1969, Darlene Ferrin and Michael Mageau drove into the Blue Rock Springs Park in Vallejo, four miles from the Lake Herman Road murder site, and parked. While the couple sat in Ferrin's car, a second car drove into the lot and parked alongside them but almost immediately drove away. Returning about 10 minutes later, this second car parked behind them. The driver of the second car then exited the vehicle, approaching the passenger side door of Ferrin's car, carrying a flashlight and a 9 mm Luger. The killer directed the flashlight into Mageau's and Ferrin's eyes before shooting at them, firing five times. Both victims were hit, and several bullets had passed through Mageau and into Ferrin. The killer walked away from the car but upon hearing Mageau's moaning, returned and shot each victim twice more before driving off.

On July 5, 1969, at 12:40 a.m., a man phoned the Vallejo Police Department to report and claim responsibility for the attack. The caller also took credit for the murders of Jensen and Faraday six-and-a-half months earlier. The police traced the call to a phone booth at a gas station at Springs Road and Tuolumne, about three-tenths of a mile from Ferrin's home and only a few blocks from the Vallejo Police Department.

Ferrin was pronounced dead at the hospital. Mageau survived the attack despite being shot in the face, neck and chest. Mageau described his attacker as a 26–30 years old, 195–200 lbs or possibly even more, 5'8" white male with short, light brown curly hair.