Patrick Wayne Kearney was born on September 24, 1939, in East Los Angeles, California. He was the oldest of three sons in a middle-class family that appeared reasonably stable. However, Kearney faced challenges early in his life. He was thin and sickly, which made him a target for bullies at school. They often beat him up and called him names, labeling him as "queer" although he had interests in girls.

As Kearney entered his teenage years, he became increasingly withdrawn. He began to have dark thoughts and developed fantasies about killing those he perceived as enemies. These thoughts sometimes included graphic fantasies of skinning them alive. Around this time, he also started to have sexual fantasies that revolved around domination. At the age of 13, Kearney began engaging in bestiality.

Patrick Kearney spent part of his childhood and early adulthood in Texas. After a brief marriage that ended in divorce, he returned to California. Kearney eventually found work as an engineer with Hughes Aircraft. During his time in California, he became skilled at attracting partners, particularly men. He often sought out partners in places like San Diego and Tijuana, Mexico. His fluency in Spanish and interest in Latin American culture helped him connect with potential partners.

In 1967, Kearney moved to Redondo Beach near Los Angeles. He was living there with a man named David Hill, who became his lover.

Patrick Wayne Kearney confessed to committing his first murder in the spring of 1962. The victim was a nineteen-year-old white male whom Kearney had convinced to ride with him to a remote area outside of Indio, California. There, Kearney shot him in the head and then sexually assaulted the body. It is unclear if the body was ever discovered. Kearney also claimed to have killed the victim's sixteen-year-old cousin, who had witnessed Kearney drive away with the first victim. Kearney's first known murder that he was convicted of took place around Christmas of 1968. This victim, referred to as "George," was lured to Kearney's home in Culver City, where he was shot in the head soon after entering. Kearney then dragged the body into his bathroom, sodomized it, and dismembered it in the bathtub.

Kearney refined his methods over the years. Starting in 1974, he began killing on a near-monthly basis. He would pick up young male hitchhikers or men from gay bars, typically shooting them in the temple with a Derringer handgun. Kearney would dispose of the victims' bodies in secluded areas, often mutilating and dismembering them first, and then putting the remains into trash bags. Many of his victims were simply left along highways or in the desert.

One of Kearney's younger victims was Ronald Dean Smith, who was just five years old when he disappeared in 1974. Kearney smothered him and later dumped his body in Riverside County. Another child victim was eight-year-old Merle "Hondo" Chance, who vanished in 1977 while riding his bicycle. Kearney claimed to have smothered him as well and disposed of his body in the Angeles National Forest.

Kearney's final confirmed victim was seventeen-year-old John Otis LaMay, whom he killed on March 13, 1977. LaMay had come to Kearney's home looking for David Hill, Kearney's partner. When Hill was not there, Kearney invited LaMay in. Without warning, Kearney shot him in the back of the head and later dismembered the body, dumping the remains in the desert.

Kearney and Hill were already under police scrutiny by this time. LaMay's remains were discovered, leading police to Kearney. After a short period on the run, Kearney turned himself in on July 1, 1977. He initially confessed to twenty-eight murders and later admitted to seven more. Kearney was charged with twenty-one counts of murder and eventually received multiple life sentences without the possibility of parole.