The First U.S. Trial Claiming Demonic Possession: How the Real Case Compares to the Film

Spoiler warning: This article reveals major plot points from The Conjuring: The Devil Made Me Do It (2021) and explains the real case behind the movie.

Can someone blame a murder on demonic possession in an American courtroom? In 1981, a Connecticut murder case brought that disturbing question into the spotlight.

The Conjuring: The Devil Made Me Do It turns the case of Arne Cheyenne Johnson into a supernatural thriller, with Ed and Lorraine Warren racing to uncover a deadly curse. But the real trial was very different from the movie—and the judge never allowed the demon defense to reach the jury.

1. The Real Case Behind the Movie

On February 16, 1981, Arne Cheyenne Johnson fatally stabbed his landlord, Alan Bono, in Brookfield, Connecticut. Johnson was 19 years old, and the killing became known as the “Devil Made Me Do It” case.

Johnson’s defense team wanted to argue that he had been possessed by a demon and therefore wasn’t responsible for his actions. This unusual claim attracted national attention.

The movie keeps the real case at its center, but adds a much larger supernatural mystery around it.

2. How Did David Glatzel Connect to the Case?

Before the killing, Johnson was dating Debbie Glatzel, whose younger brother David reportedly experienced frightening episodes that his family believed were signs of demonic possession.

The Glatzel family sought help, and paranormal investigators Ed and Lorraine Warren became involved. According to the family’s account, Johnson challenged the demon to leave David and enter him instead.

The film shows this moment as a dramatic transfer of possession. However, the supernatural explanation was disputed in real life, and it was never scientifically established.

3. Did the Warrens Really Investigate Arne Johnson?

Yes. The real Ed and Lorraine Warren were involved with the Glatzel family and the claims surrounding Johnson.

But the movie gives them a far more active role in solving the murder. On screen, they follow clues, investigate strange deaths, and uncover a hidden occult plot.

The real case did not produce verified evidence of such a conspiracy. The Warrens’ interpretation of events was one account among competing views.

4. The Occultist Was a Movie Invention

One of the film’s biggest twists is the discovery of Isla, a mysterious occultist who curses victims through dark rituals.

There was no established real-life figure matching this villain in the Johnson case. The curse, the ritual objects, and the occultist’s plan were created for the movie.

These additions give the story a clear enemy and let the Warrens investigate like supernatural detectives. The actual trial, however, focused on criminal responsibility—not a hunt for a hidden spellcaster.

5. Did the Judge Allow the Demon Defense?

No. This is one of the most important differences between the real case and the film.

Johnson’s attorney, Martin Minnella, intended to argue that demonic possession explained the killing and planned to call religious experts as witnesses. On October 28, 1981, Judge Robert J. Callahan rejected the defense, ruling that evidence of possession was not relevant to the trial.

The movie gives the impression that the supernatural claim remains a major part of the courtroom drama. In reality, the jury was not permitted to decide Johnson’s guilt based on demonic possession.

6. What Defense Did Johnson Use Instead?

After the judge rejected the possession argument, the defense shifted toward a claim of self-defense.

That meant the case had to be considered through evidence and legal arguments about the killing, rather than whether a demon had controlled Johnson.

The change matters because it shows how different the real courtroom proceedings were from the film’s supernatural investigation.

7. What Was the Verdict?

On November 24, 1981, Johnson was convicted of first-degree manslaughter. On December 18, he was sentenced to 10 to 20 years in prison. He ultimately served about five years.

The outcome did not establish that possession was real or that a demon caused the murder. It was a criminal conviction after the court rejected the proposed demon defense.

8. Why Is the Case Still Famous?

The case became famous because it pushed an extraordinary claim into a serious criminal trial: could a defendant argue that a supernatural force controlled his actions?

The case is often described as the first U.S. murder trial in which demonic possession was attempted as a defense. That does not mean the court accepted the claim—it specifically ruled it out.

The case remains controversial because the people involved gave different accounts of the alleged possession, and no accepted scientific evidence proved a supernatural cause.

Final Verdict: Real Trial, Fictional Horror

The Conjuring: The Devil Made Me Do It draws on a real murder, real people, and a genuine attempt to use demonic possession as a defense. But the occultist, the curse, and the Warrens’ dramatic battle against supernatural forces are fictional additions.

The biggest real-life twist is that the demon defense never reached the jury. Johnson was convicted of manslaughter, and the case became famous not because a court proved possession existed, but because a judge refused to let it serve as a legal explanation.