The Mind of a Monster: Billy Milligan’s Bizarre Trial and the Insanity Plea That Shocked America
In October 1977, authorities arrested 22-year-old Billy Milligan and charged him with the kidnapping, robbery, and rape of three Ohio State University (OSU) students. What seemed like an open-and-shut case soon spiraled into one of the most shocking trials in American history. Milligan claimed he wasn’t responsible for the crimes—not because he was innocent, but because someone else inside him did it.
An OSU police officer who rode with Milligan to the Columbus, Ohio police headquarters later recalled in a 2007 interview with The Columbus Dispatch, “I couldn’t tell you what was going on, but it was like I was talking to different people at different times.”
The Man with 24 Personalities
During a psychiatric evaluation, Milligan made a mind-boggling claim: he wasn’t the one who had committed these crimes. Instead, two of his alternate identities—Ragen and Adalana—were responsible. Ragen was behind the robberies, while Adalana, a shy and timid female alter, was responsible for the sexual assaults. As experts dug deeper, they discovered that Milligan claimed to have a staggering 24 alternate personalities.
Then came the bombshell: On December 4, 1978, in a landmark ruling, Billy Milligan became the first defendant in U.S. history to be found not guilty by reason of insanity due to multiple personality disorder (now known as dissociative identity disorder, or DID). It was a verdict that stunned the legal world and sparked an intense debate that continues today.
A Diagnosis That Shaped the Trial
Milligan was diagnosed with what was then known as multiple personality disorder (MPD) by nine different mental health professionals. Among them was Cornelia Wilbur, the psychiatrist famous for diagnosing Sybil, the woman whose story popularized the controversial disorder. At the time, MPD was believed to be caused by extreme trauma, leading victims to mentally escape by creating different identities.
But not everyone was convinced. As the trial progressed, prosecutors and skeptics questioned whether Milligan was truly suffering from DID—or if he was an expert manipulator gaming the system to avoid prison.
The Evidence That Split the Courtroom
Milligan’s defense team leaned heavily on his mental illness to argue that he was incapable of understanding right from wrong. They presented evidence of his past hospitalizations for psychiatric issues, his history of dissociative tendencies, and his claim of severe childhood abuse at the hands of his stepfather (who denied the allegations and was never charged).
Adding to the intrigue, eyewitnesses provided conflicting descriptions of Milligan’s behavior. One of his victims described him as soft-spoken, while another recalled an accent that didn’t match. A police officer who interacted with him reported that it felt like he was speaking to different people.
Despite Milligan’s history of run-ins with the law, the jury accepted the insanity plea—something that rarely succeeds in court. The judge ruled him not guilty, and shockingly, the prosecution did not challenge the verdict.
Would Milligan Have Been Acquitted Today?
Forensic psychologist Joni Johnston, who has studied the case extensively, is doubtful. “Today, I do not think he would be found legally insane,” she explains. While mental illness can impact a defendant’s mindset, the law requires a direct link between the illness and the crime. “Most people who commit violent offenses are not mentally ill,” Johnston says. “If Milligan had DID, what in his mental illness made him commit rape? There needs to be some direct link between a person’s symptoms and the crime they committed.”
Legal experts argue that since DID is now understood differently, a defense like Milligan’s would face much greater scrutiny in today’s courts. Simply having a mental illness does not automatically excuse someone from criminal responsibility.
The Aftermath of a Controversial Verdict
Milligan’s case left an undeniable mark on the legal system, but it did not set a major precedent. The insanity defense remains one of the most difficult legal arguments to win. While his acquittal allowed him to avoid prison, Milligan spent years in mental institutions before his eventual release. His story was later chronicled in the book The Minds of Billy Milligan and inspired Netflix’s Monsters Inside: The 24 Faces of Billy Milligan.
But his case raises a chilling question that still haunts the legal world today: Can someone with dissociative identity disorder truly be held accountable for violent crimes? And if they can’t—where do we draw the line between illness and calculated deception?
