Born on April 18 1947, and raised in Santa Cruz, California, Mullin had a relatively normal childhood. His father, a World War II veteran, was stern but not abusive. He frequently discussed his heroic war activities and showed his son how to use a gun at an early age. Mullin had numerous friends at school and was voted "Most Likely to Succeed" by his classmates. However, shortly after graduating from high school, one of Mullin's best friends was killed in a car accident, and Mullin was devastated. He built a shrine to his deceased friend in his bedroom and later expressed fears that he was gay, even though he had a long-term girlfriend at the time.
As he entered adulthood, Mullin's behaviour became increasingly unstable. He broke off his relationship with his girlfriend for no apparent reason, started obsessing over impending earthquakes and began asking his sister to have sex with him. He claimed a desire to go to India to study religion, although he never did so.
In 1969, at the age of 21, Mullin allowed his family to commit him to a mental hospital. Over the next few years, he would enter various institutions, but would discharge himself after only a short stay. He burned cigarettes out on his own skin, talked to himself, attempted to enter the priesthood, and got evicted from an apartment after he repeatedly pounded on the floor, shouting at people who were not there.
By 1972, Mullin was 25 and had moved back in with his parents in Santa Cruz. By now he was hearing voices in his head that told him an earthquake was imminent, and that only through murder could he save California (Mullin's birthday, April 18, was the anniversary of the 1906 San Francisco earthquake, which he thought very significant).
On October 13, 1972, Mullin went out and battered a homeless man to death with a baseball bat. He was to claim that the victim was Jonah from the Bible, and that he had sent Mullin a telepathic message saying, "Pick me up and throw me over the boat. Kill me so that others will be saved."
The next victim was Mary Guilfoyle, 24, whom Mullin picked up hitch-hiking. He stabbed her to death, sliced open her stomach and dumped her corpse at the side of the road. He then strung her intestines along the tree branches to examine them of "pollution". When Guilfoyle's body was found, it was mistakenly thought to be a victim of Edmund Kemper, another serial killer operating in the area at the time.
In November, Mullin claimed his third victim when he went to confess his sins but ended up stabbing the priest, Father Henri Tomei, to death. After that, Mullin decided to join the U.S. Marines and actually managed to pass the physical and psychiatric tests. However, he was refused entry when it was found out that he had a number of minor arrests for his bizarre and disruptive behaviour in the past. This rejection fueled Mullin's paranoid delusions of conspiracies, behind which he believed was a powerful group of hippies.
Having purchased several guns, Mullin decided to kill Jim Gianera, a high school friend who had sold him cannabis. However, when Mullin went to Gianera's house on January 25, 1973, he found that his old friend had moved away. The house was now occupied by Kathy Francis, and she gave him Gianera's new address. There, Mullin slaughtered both Gianera and his wife with shots to the head, then stabbed their bodies repeatedly. Mullin then went back to Francis' house, where he shot her and her two sons, aged 9 and 6, dead. Because Francis' husband, who was away at the time, was a drug dealer, the five murders were thought to be motivated by drug trafficking. (It would later be pointed out by prosecutors that the murder of Kathy Francis eliminated Mullin's claims of not guilty by reason of insanit] because he killed her to remove a witness who could link him to the Gianera murders.)
On February 10, Mullin was wandering around Henry Cowell Redwoods State Park where he saw four teenaged boys out camping. He walked over to them, engaged in a brief conversation and claimed to be a park ranger, then, without provocation, pulled out a gun and shot all of them to death.
The final murder took place three days later on February 13. Mullin was driving alone when he pulled over and shot dead an elderly man who was mowing his lawn. Then he got back into his car and drove off. It was broad daylight and there were a number of witnesses, and Mullin was quickly arrested. In the space of four months he had killed 13 people.
Trial and imprisonment
In custody, Mullin confessed to his crimes, and said that he had been told by voices in his head to kill people in order to prevent an earthquake (and he claimed the fact that there had not been an earthquake recently was due to his handiwork).
Mullin was eventually charged with 10 murders (he was not charged with the first three), and his trial opened up on July 30, 1973. Mullin had admitted to all the crimes and therefore the trial focused on whether he was sane and culpable of his actions. The fact that he had covered his tracks and shown premeditation in some of his crimes was put forth by the prosecution, while the defense argued that the defendant had a history of mental illness. On August 19, the verdict was delivered. Mullin was declared guilty of first-degree murder in the cases of Jim Gianera and Kathy Francis, because they were premeditated, while for the other eight murders Mullin was found guilty of second-degree murder because they were more impulsive.
He was sentenced to life imprisonment and will be eligible for parole in 2025, when he will be 77.