Malcolm Joseph Robbins Jr. was born on July 7, 1960, in Rockland, Maine. He grew up in a big family with many siblings. It was said that his mother had him after being with her older brother, Donald, who was in jail when Malcolm was born. The family was very poor, and Malcolm's mother worked as a waitress and sometimes as a prostitute. They mostly lived on welfare benefits.

From an early age, Malcolm showed signs of mental problems. He couldn't walk until he was three years old and got kicked out of kindergarten for causing trouble. His relatives said that his mother’s housemates sexually abused him, which affected his mind. He was bullied at school and seen as a social outcast. Teachers often complained about his dirty appearance and his refusal to talk to others.

In 1970, a school psychologist visited Malcolm's home to tell his mother that his grades were getting worse, but she didn't seem to care. The psychologist wrote that the family's living conditions were terrible and not good for any child. A year later, Malcolm was kicked out of school and sent to a place for troubled kids. After a few days, he was moved to the Pineland Hospital and Training Center in New Gloucester for observation. He stayed there for nine months.

In 1973, Robbins was released from an institution but returned the following year after being caught abusing two boys. By the fall of 1974, his behavior and mental state worsened significantly, leading to frequent disciplinary actions and solitary confinement. He attempted suicide at least once. After undergoing psychiatric treatment, he was released to his mother's custody in April 1975, but was arrested again in September for another assault.

After a court evaluation, Robbins was declared insane and sent back to the institution for delinquent youths. He stayed there until August 1976 when his aunt gained custody of him. Living with his aunt and her husband, Robbins became interested in his stepfather's job as an auto mechanic, learning about various car models and tools.

In October 1976, Robbins faced child molestation charges, but they were dropped after the victim's parents forgave him on behalf of his aunt. Despite staying at his aunt's house, he was ordered to attend regular psychiatric treatment, which he disliked. Psychiatrists found him aggressive and obsessed with firearms. In June 1977, Robbins was arrested again for sexually abusing minors but only had to pay a small fine.

In early 1978, Robbins ran away and began relationships with gay men. By mid-year, he left Maine with one of these men and moved to California, living in Palm Springs with a 40-year-old lover. In late 1979, he moved to Los Angeles, befriended another man at a gay club, and they moved in together. In June, they relocated to Santa Barbara, where Robbins quickly began a new relationship.

Around this time, Robbins started drifting around the country, leaving California and visiting several states in a few months. Friends described him as a pathological liar and manipulator with poor impulse control. Back in Los Angeles, he claimed to be an undercover officer hunting the Freeway Killer, but no one believed him due to his history of lies.

On November 26, 1980, Robbins was arrested in Millville, New Jersey, for the murder of 9-year-old Evan Bailey. He led authorities to the dumping site, where Bailey's raped, beaten, and stabbed body was found. Robbins confessed and shocked investigators by admitting to similar murders in other states.

His first known victim was 7-year-old Steven Craig Little, killed on December 27, 1979, in Dallas, Texas. Robbins lured Little into his van, raped, strangled, and burned his body. Despite recanting his confession, he had detailed information known only to investigators.

Robbins' next victim was 17-year-old William Bryan Lepko, missing from Wheeling, West Virginia, on January 29, 1980. Lepko went to a party with Robbins, who later stabbed him during a fight. Lepko's body was found in February 1981. Another victim was 6-year-old Christopher Michael Finney, who went missing on June 15, 1980, from Isla Vista, California. Witnesses last saw Finney with a man on a red motorcycle. Robbins confessed to killing Finney, and police found Finney's T-shirt in Robbins' apartment.

Robbins claimed other murders, like an unidentified boy in Nevada in 1980, later identified as 15-year-old John Edward Powers. He was also suspected but ruled out in the murders of Teresa Lynn Flores and Martha Joanne Mezo in California and the Atlanta Child Murders.

Robbins' New Jersey trial for Evan Bailey's murder began in April 1981. He pleaded guilty and was sentenced to life imprisonment with a chance of parole after 30 years. In California, he made a plea bargain for Christopher Finney's murder, resulting in a death sentence in May 1983. Between 1983 and 1989, Robbins was convicted of Steven Little and William Bryan Lepko's murders in Texas and Maine. California requested his extradition for execution, which New Jersey granted after legal proceedings.

Robbins spent his remaining years on California's death row. In March 2019, Governor Gavin Newsom placed a moratorium on capital punishment, and Robbins was moved to Corcoran State Prison. His health declined, and he died from natural causes on January 27, 2023, at age 62, after spending 42 years awaiting execution.