Herbert William Mullin (April 18, 1947[1] – August 18, 2022)[2] was an American serial killer who killed 13 people in California in the early 1970s.

In 1973, after a trial to determine whether he was legally insane or culpable, he was convicted of two murders in the first-degree and nine in the second-degree and sentenced to life imprisonment.

[3][4] Mullin and Edmund Kemper overlapped in their 1972 to 1973 murder sprees, adding confusion to the police investigations and ending with both being arrested within a few weeks of each other after the deaths of 21 people.

[16] He later claimed his victim looked like Jonah from the Bible and sent him telepathic messages: "Hey, man, pick me up and throw me over the boat.

"[15] Mullin soon set out to commit a second murder with the intent to both test his hypothesis that the environment was being rapidly polluted and to follow a command hallucination of his father's voice directing him to make another sacrifice.

[16] On October 24, 1972, Mullin encountered Mary Margaret Guilfoyle, a student from Cabrillo College who was running late for an appointment.

This uncertainty led Mullin to attend St. Mary's Catholic Church in Los Gatos on November 2, 1972, with the aim of confessing.

[19] Around January 1973, Mullin applied to join the United States Marine Corps in an attempt to legally conduct what he perceived as his mission but was barred entry when he refused to sign his criminal record.

[13] By the start of 1973, Mullin had stopped taking drugs completely and began blaming the faults in his life on his previous substance use.

[19][23] In early January 1973, Mullin drove to a remote area of Santa Cruz, recalling Gianera had lived there.

[26] About a month later, on February 10, 1973, Mullin was hiking in the state park in Santa Cruz,[27] where he encountered four teenage boys (Robert Spector, aged 18, Brian Scott Card, 19, David Oliker, 18, and Mark Dreibelbis, 15) camping illegally.

[26] He noticed his victim, a 72-year-old retired prizefighter and fishmonger named Fred Abbie Perez,[31] working in his garden in Santa Cruz.

[25] Mullin did a U-turn, came back down the street, stopped, put the rifle across the hood of his car, and shot Perez once in the heart.

[26] A few minutes after the description was broadcast on the police radio, a "docile" Mullin was ordered to pull over and was arrested by a patrolman.

[32] The police failed to recognize a pattern at the time of Mullin's murders due to several factors: firstly, the murders did not appear to be connected by a similar weapon or modus operandi; secondly, the victims differed from each other in terms of age, race, and sex; and finally, Edmund Kemper, who would kill the last of his own eight victims just a few weeks later, was operating in approximately the same area at the same time.

[35] The fact that he had covered his tracks and shown premeditation in some of his crimes was highlighted by prosecutor Chris Cottle,[36] while the defense (public defender Jim Jackson) argued that Mullin's delusions made him kill.