Described by the prosecutor at his first trial as "the most arch-evil person who ever existed",[5] he spent 14 years on death row before his execution by lethal injection at San Quentin State Prison in 1996.

[47] Stationed in Phu Loi Base Camp, he served five months of active duty in the 205th Assault Support Helicopter Unit as an aerial gunner, logging over 700 hours of combat and patrol time.

[63][62] On December 4, it was reported to the Torrance Police Department by 17-year-old Allen Pruitt that a man with medium-length dark hair and olive complexion had offered him a ride before deviating from the highway and handcuffing the boy, who was extensively sexually assaulted in the vehicle.

[68] In May, Bonin recounted to a probation officer his recent stressful separation, and admitted his guilt in molesting male youths, although he also expressed desire to start a family and become a pilot upon his release.

He pleaded guilty to molestation and forced oral copulation, and was sentenced to the Atascadero State Hospital in June 1969 as a mentally disordered sex offender considered amenable to treatment.

[71] Bonin pleaded guilty to both charges and on December 31, 1975, he was sentenced to serve between one and fifteen years' imprisonment at the California Men's Facility in San Luis Obispo.

[107] At the time of his initial acquaintance with Bonin, Butts had developed a local reputation as an eccentric figure[108] who had recently been fired from his employment as a magic store clerk due to his unkempt appearance and increasingly strange and unpredictable behavior.

[23] One attorney present for Bonin's eventual court case said the escalating levels of brutality he had exhibited toward his victims had been similar to that of a drug addict, requiring an ever-greater increase of dosage to maintain their euphoria.

[128] Bonin also likened his urges to addiction, emphasizing to neurologists his feelings of extreme restlessness and sexual frustration in the hours prior to his murders,[129] and that he had felt an intense sense of excitement as he drove in search of his victims.

[132][71] Dr. Albert Rosenstein, a forensic psychologist, predicted the killer was an intelligent sex offender in his late twenties or early thirties, had spent time in a psychiatric facility, and was abused as a child.

He gradually developed a reputation as a child molester among local residents, due to his habit of inviting young boys into his house, under the guise of providing alcohol and viewing pornography with them.

[96][93] Bonin angered his boss (who was unaware of his status as a sex offender) by picking up hitchikers in his presence on one occasion, and by taking long, unnecessary routes (which detectives later took interest in).

[225] On May 28, he overheard the details of the ongoing murders on a local radio broadcast, and confided to a counselor that he knew the perpetrator's modus operandi, which was described to him by Bonin two months prior.

[204][226][n 10] That same day, Bonin invited 18-year-old homeless drifter James Michael Munro — whom he had encountered while cruising for young male prostitutes[228]⁠— to move into his family's home in exchange for sex.

Although initially alleging his innocence in the murders, Bonin confessed his guilt to St. John after reading a letter from Sean King's mother, imploring him to reveal the location of her son's body.

[256] Bonin made sure to clarify, however, that it was not to ease the mother's pain,[255] but on the knowledge that, because King was buried in San Bernardino County, police would likely buy him a hamburger for lunch on the extensive trip.

The Los Angeles County Sheriff's Department told the press: "Bonin and Butts are believed to be responsible for the kidnapping, torture and murder of at least 21 young males between May 1979 and June 1980", 14 of which had been committed in their jurisdiction.

[265] He claimed that, upon their successfully luring a victim into the van, he would typically drive a short distance, before stopping the vehicle in order to assist Bonin in restraining and torturing their captive.

After police learned Pugh had willingly accompanied Bonin in Harry Todd Turner's murder, Wijnaendts' charges were dropped in January 1981,[273] with the county prosecutor citing insufficient evidence as the cause.

[117] He had attempted suicide at least four times prior to his arrest;[266] his attorney, Joe Ingber, theorized that his depressive state had been magnified by the impending release of transcripts of his client's testimony at the preliminary hearing, in which Butts had graphically described his victims' torture.

[192] The strategy of Charvet and Stewart was to challenge the credibility of the prosecution's witnesses, and to suggest that significant mitigating factors as to the causes of Bonin's behavior lay in the extensive physical, sexual, and emotional abuse he had endured throughout his early life.

[219] On November 24, prison inmate Lloyd Douglas testified that Bonin had bragged to him of his culpability in the Freeway Killer murders, while both were in Los Angeles County Jail in 1980.

[288][n 13] Against overruled objections from the defense, Fresno-based reporter David López waived his previously sought immunity under California's shield law, and agreed to testify on behalf of the prosecution as to the details of seven interviews Bonin had granted him (between December 1980 and April 1981).

This motion was refused by Judge Kenneth Lae, who ruled in November that there had only been minimal publicity surrounding Bonin's case in Orange County following his earlier convictions.

Bonin's attorney then renewed an earlier filed motion that the trial should be moved outside of Orange County due to pretrial publicity tainting the jury pool.

[314] He became close friends with convicted murderers Lawrence Bittaker, Randy Kraft (who shared the nickname "Freeway Killer"), Douglas Clark, and Jimmy Lee Smith.

Bonin was executed by lethal injection inside the gas chamber at San Quentin State Prison on February 23, 1996,[324] 14 years after his first death sentence had been imposed.

[325] In his final interview, given to a local radio station less than 24 hours before his death, Bonin said that he had "made peace" with the fact he was about to die, adding that his only major regret in life was that he had not pursued his teenage passion of bowling long enough to turn professional.

[332] In his final statement, given to the prison warden an hour before his scheduled execution at midnight, Bonin again expressed no remorse for his crimes; he left a note that stated: I feel the death penalty is not an answer to the problems at hand.

[335] Throughout Bonin's trials, and in the years of his subsequent incarceration on death row, experts devoted much speculation and debate as to whether the root cause of his crimes lay in his abusive and dysfunctional upbringing.