Leslie Van Houten was born on August 23, 1949, in Altadena, California, to a middle-class family. Her parents, Paul Van Houten and Jane Edwards, divorced when she was 14, a turning point that marked the beginning of her rebellion. By age 15, she had begun using LSD and marijuana. At 17, she ran away with her boyfriend but returned to graduate from Monrovia High School in 1967. Soon after, she became involved in counterculture movements, embracing yoga and communal living. A traumatic experience during this period, when her mother allegedly forced her to abort a pregnancy and bury the fetus, caused deep emotional scars and severed her emotional ties with her family.

Van Houten’s search for meaning and belonging led her to a commune in Northern California, where she met Catherine Share and Bobby Beausoleil. When Share joined Charles Manson’s group, Van Houten soon followed, joining the Manson Family at the age of 19. She completely cut ties with her past, informing her mother she would no longer be in contact. Life with the Family was deeply controlled by Manson, who orchestrated group sex, drug trips, and spiritual manipulation. Van Houten, under the influence of constant LSD use, later claimed she lost touch with reality and her moral compass.

At Spahn Ranch, Manson’s cult-like control grew. Women were encouraged to surrender their identities and individuality, and Van Houten was assigned to another Family member, Bobby, as if she were his property. According to her own accounts, she became fully immersed in Manson’s ideology and structure, viewing herself as an instrument of his will. She was described by some witnesses as a "leader" within the Family and reportedly helped reinforce Manson’s dogma among other members.

On the night of August 10, 1969, the day after the Tate murders, Charles Manson orchestrated another brutal home invasion—this time targeting the Los Feliz home of Leno and Rosemary LaBianca. While Manson initially entered the house with Tex Watson, he later left and instructed his followers to finish the job. Van Houten, along with Patricia Krenwinkel and Tex Watson, entered the LaBianca residence where Leno was bound and murdered. Rosemary was then assaulted, stabbed, and mutilated.

Tex Watson stabbed Leno LaBianca multiple times before directing the women to kill Rosemary. Van Houten testified during her 1971 trial that she held Rosemary down, then took a knife from Watson and stabbed her more than a dozen times—at least 14 wounds were inflicted by Van Houten alone. She later admitted to stabbing Rosemary postmortem but has also acknowledged over time that Rosemary may have still been alive during the assault. During the trial, Van Houten declared in open court, “We started stabbing and cutting up the lady.”

She was convicted in 1971 of first-degree murder and sentenced to death. However, her sentence was automatically commuted to life in prison in 1972 when the California Supreme Court overturned the death penalty. She became eligible for parole after seven years but was repeatedly denied. A retrial in 1977 ended in a hung jury, but in 1978, she was reconvicted and sentenced to life in prison with the possibility of parole.

In the decades following her conviction, Van Houten publicly denounced Charles Manson and expressed remorse for her crimes. She actively participated in therapy and prison programs, edited a prison newspaper, and was mentored by feminist scholars and activists. Despite multiple parole recommendations by the California Parole Board in the 2010s and early 2020s, her release was blocked several times by Governors Jerry Brown and Gavin Newsom.

On May 30, 2023, the California Court of Appeal ruled that Governor Newsom's continued parole denials lacked sufficient evidence that she posed a danger to society. On July 7, 2023, Newsom announced he would not appeal the decision, clearing the way for her release. Van Houten was officially paroled on July 11, 2023, after serving over 52 years in prison—the longest of any female inmate convicted in connection with the Manson murders.