Picture a courtroom where a defendant insists that another person living inside his mind committed the murders. That scenario played out in several high-profile cases involving serial killers and violent offenders who pointed to dissociative identity disorder as the reason for their actions.

This article takes a close look at five such cases. It covers the backgrounds of the men involved, the details of their crimes, the specific claims they made about multiple personalities, how those claims were tested in court, and what the outcomes reveal about mental health defenses. The focus stays on verified facts while respecting the victims and their families at every turn.

1. Kenneth Bianchi: The Hillside Strangler’s “Steve Walker”

Kenneth Bianchi, one half of the infamous Hillside Strangler duo, terrorized Los Angeles in the late 1970s. Born in 1951 in Rochester, New York, Bianchi endured a troubled childhood marked by headaches, bed-wetting, and petty crimes. He moved to California in 1976, linking up with his cousin Angelo Buono, a misogynistic dressmaker. Together, they abducted, raped, tortured, and strangled at least 10 young women, dumping their bodies on hillsides in Glendale and Eagle Rock.

Victims included Dolores Cepeda, 12, and Sonja Johnson, 14, lured with job promises; Kristina Weckler, 20, asphyxiated with gas; and Jane King, 28, among others. The brutality shocked the city, with autopsies revealing ligature marks, sexual assault, and posed bodies. Bianchi fled to Bellingham, Washington, in 1979, where he killed two more students, Karen Mandic and Diane Wilder, under similar circumstances.

Those Washington murders became the turning point. Police quickly connected the crimes to the Los Angeles pattern, and the evidence against both men grew overwhelming. Bianchi’s attempt to shift blame onto an alter ego named Steve Walker only deepened the scrutiny once experts began comparing his story to known facts about the killings.

The Multiple Personality Defense

Arrested and facing overwhelming evidence, Bianchi underwent psychiatric evaluation. Under hypnosis, he revealed an alter named “Steve Walker,” a drifter who supposedly committed the Washington murders while the “real” Bianchi was passive. Therapists described Steve as aggressive and detached. However, experts like Dr. Martin Orne later exposed the fraud: Bianchi had studied DID from books and mimicked symptoms flawlessly, even fooling initial examiners.

Prosecutors linked him inextricably to Buono via witness testimony, tire tracks, and fibers. Bianchi pleaded guilty to avoid execution, testifying against Buono. Sentenced to life without parole in 1984, he remains at Walla Walla State Prison. His case popularized skepticism toward DID claims in court, influencing future evaluations.

That skepticism proved useful in later trials because it encouraged courts to demand stronger proof beyond hypnosis alone. Bianchi’s story showed how easily someone could learn symptoms from popular books and repeat them during sessions, which forced psychologists to develop tighter testing methods.

2. Bobby Joe Long: Duality of Rage in Florida

Bobby Joe Long’s killing spree unfolded in Tampa Bay, Florida, during 1984. Born in 1953, Long suffered severe head trauma at age five from a car wreck, followed by blackouts, migraines, and hypersexuality possibly tied to Klinefelter syndrome. His early life included abuse allegations and failed marriages. By his 30s, he was burglarizing homes and escalating to violence.

Long raped at least 10 women after binding them in their residences, then murdered nine confirmed victims, including Virginia Johnson, 26, beaten and strangled; Artis Wick, 20; and Michelle Simms, 22, shot and posed. He used gloves, knives, and nylon stockings, often revisiting crime scenes. A survivor, Lisa McVey, provided crucial details leading to his capture.

McVey’s survival mattered because she remembered enough details about the car and the route to help police narrow their search quickly. Her account turned what could have been another unsolved case into an arrest that stopped the spree.

Diagnosis and Trial

Evaluated pre-trial, Long received a DID diagnosis from Dr. Robert Sadoff, identifying alters like “Billy” (benign) and violent ones triggered by rage. Long described switches during blackouts. Yet, psychologists debated authenticity, noting his high-functioning manipulation and lack of amnesia for crimes.

The jury rejected the insanity plea in 1985, convicting him on 17 counts including nine murders. Sentenced to death, Long exhausted appeals and was executed by lethal injection on May 23, 2019. His case highlighted DID’s diagnostic challenges, with some experts attributing violence to antisocial personality disorder amplified by trauma.

Long’s execution closed a chapter that had stretched across decades of appeals. It also underscored how juries weigh documented brain injury against claims of sudden personality switches when the defendant shows clear planning in other parts of his life.

3. William Heirens: Chicago’s Lipstick Killer

In post-World War II Chicago, William Heirens became the “Lipstick Killer” through three 1945-1946 murders. Born in 1928 to strict parents, Heirens was a brilliant student with a burglary habit starting at 13. He attended University of Chicago at 16 but lived a double life, writing taunting messages like “For heaven’s sake catch me before I kill more. I cannot control myself.”

Victims were Josephine Ross, 43, slashed in her apartment; Frances Brown, 32, shot with “look out” scrawled in lipstick; and suffocated child Suzanne Degnan, 6, whose dismembered body parts were found in sewers. Heirens left fingerprints and bloody clothing linking him.

The lipstick messages on the wall became one of the most memorable details because they suggested the killer wanted attention. At the same time, the presence of clear physical evidence like fingerprints made it harder for any later defense to argue complete separation from the crimes.

Three Personalities Emerge

Heirens confessed under sodium pentothal (“truth serum”) and hypnosis, claiming three alters: himself (law-abiding student), “George Murman” (burglar), and “William Daniel Gerard” (killer). He alleged blackouts and internal voices commanding violence. Psychiatrists confirmed DID, but critics pointed to coerced confessions and no independent alter verification.

Pleading guilty to avoid the electric chair, he received three life terms in 1946. Paroled considerations failed due to public outcry; he died in prison in 2012 at 83, maintaining innocence to the end. His saga fueled debates on juvenile brain development and suggestibility in interrogations.

Heirens was only 17 when the crimes occurred, which later researchers used to examine how young defendants can be influenced by intense questioning. The case still serves as a reference point when courts consider whether certain interrogation techniques risk producing unreliable statements.

4. Arthur Shawcross: The Genesee River Killer’s Blackouts

Arthur Shawcross preyed on Rochester, New York, prostitutes in 1988-1989, earning the moniker Genesee River Killer. Born in 1945, he claimed childhood abuse and Vietnam War atrocities (unsubstantiated). Convicted in 1972 for murdering two children, 10-year-old Karen Ann Hill and 8-year-old Sheila Feegan, he served minimal time before release in 1987.

Post-release, he killed 12 women, including Dorothy “Dotsie” Blackburn, 27; June Stott, 30; and Felicia Stephens, 19. Bodies surfaced strangled or beaten along the Genesee, some cannibalized per his confessions. He targeted vulnerable sex workers, posing as a client.

The early release after the 1972 murders later drew heavy criticism because it showed gaps in how parole boards assessed ongoing risk. Shawcross had already demonstrated violence against children, yet he was returned to the community with limited supervision.

Alters or Fabrication?

Captured via saliva on a victim, Shawcross underwent testing revealing low IQ and organic brain damage. He described blackouts and an alter “Mitch,” a cruel persona from Vietnam, responsible for kills. Polygraphs and hypnosis sessions supported switches, but forensic psychologist Dr. Alexander L. Thomas deemed it malingering.

Convicted in 1990 on 10 murders, he received 250 years. Shawcross died in prison in 2008 from a heart attack. His case underscored parole system failures and DID’s unreliability as a mitigator when prior violence existed.

Brain damage findings added another layer because they raised questions about impulse control without proving that separate personalities existed. Courts had to weigh medical evidence against the practical reality that Shawcross had hidden bodies and chosen specific locations, actions that suggested awareness and planning.

5. Billy Milligan: The Man with 24 Alters

While not a strangler or shooter, Billy Milligan’s case epitomizes DID in violent crime, with multiple assaults qualifying him in broader serial offender discussions. Born in 1955 in Miami Beach, Milligan endured horrific abuse: stepfather beatings, mother’s instability, and suicide attempts. By 1977, at 22, he had 24 diagnosed alters, including “Ragan” (escape artist) and violent “Adalana” (female rapist).

In Columbus, Ohio, alters committed three rapes, two kidnappings, and a robbery targeting female students. Victims survived, aiding identification via composites matching Milligan.

Milligan’s case stood out because the victims lived to describe what happened. Their accounts helped build a clearer picture of how different behaviors appeared during the attacks, which therapists later used when mapping the alters.

Acquittal and Legacy

Psychiatrist Dr. David Caul confirmed DID via interviews, with alters emerging in therapy. Milligan had no memory of crimes, committed by “the Teacher” collective. In a landmark 1978 trial, he was found not guilty by insanity—the first such U.S. case for DID. Committed to a facility, he underwent fusion therapy and was released in 1988.

Milligan died in 2014. His story, chronicled in The Minds of Billy Milligan, advanced DID awareness but drew criticism for leniency, sparking “Son of Sam” laws limiting insanity defenses.

As explored further on Dyerbolical at https://dyerbolical.com/about-us/, Milligan’s acquittal changed how some states handled mental health pleas. It also prompted new laws that restricted profits from crime stories, showing how one case can ripple into broader legal reforms.

Bibliography

Daniel Keyes, The Minds of Billy Milligan (1981)

Official court transcripts from the Kenneth Bianchi and Angelo Buono trials, Los Angeles Superior Court

Contemporary news coverage from the Tampa Tribune on the Bobby Joe Long case and 2019 execution

Chicago Police Department records and Heirens confession documents, 1946

Forensic psychology reports on Arthur Shawcross by Dr. Alexander L. Thomas

DSM-5 criteria and subsequent studies on dissociative identity disorder in legal contexts

Parole board documents and victim advocacy reports regarding Shawcross release in 1987

Interviews and evaluations published in psychiatric journals covering the Milligan trial outcome

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