Texas detectives looking into the death of a teenager, Ashley Nicole Wilson, in January had wrongly concluded she hanged herself after they found a suicide note.
But after sitting through the powerful two-hour film, Ms Wilson’s boyfriend, Dan Leach, felt the need to confess and turned himself in to Fort Bend County police.
He admitted staging the murder of his pregnant lover to look like a suicide after picking up the idea from a US crime show, but he was so moved by the film he could no longer keep the secret.
"He wanted redemption," said Detective Mike Kubricht of the Fort Bend sheriff’s office. "The Passion of the Christ moved him spiritually and he felt compelled to come forward with this."
According to Det Kubricht, Leach’s confession was preceded by a bizarre address to members of the Avenue N Church of Christ in Rosenberg, Texas.
"He told them that he was about to go on a journey that was going to take him away for a long time, and that he wanted the congregation to support him in prayers," he said.
Later that day, Leach, 21, told his family he had killed Ashley, and wanted the minister of the church to come to his house to hear his confession.
The minister and three church elders persuaded Leach to turn himself in, and accompanied him to the police station.
"We asked him why he came forward now, and he said that he had seen The Passion of the Christ, and that moved him," Det Kubricht told the Houston Chronicle.
"His motive for killing her was because she was pregnant and he was embarrassed of it and he wanted her totally out of his life. He expressed no remorse."
Ms Wilson’s parents, Dan and Renee Wilson, had became worried about their daughter in January after not hearing from her for several days and found her hanging in her flat by the cord of her high school graduation gown, with the purported suicide note next to the body.
Until Leach’s confession, police, and the medical examiner who performed the autopsy, said Ashley’s death was a suicide. Leach apparently wore gloves and left no traces of DNA at the scene, Det Kubricht said.
"He was very, very meticulous. It was very well planned and well executed," Det Kubricht said. Leach has been charged with the murder.
It turned out that Leach, an avid fan of the TV show CSI, Crime Scene Investigations, had re-enacted a scene in which a murder victim was persuaded to indulge in psychotherapy by writing a letter detailing everything that was wrong in her life, with the letter then used as a suicide note in an effort to throw detectives off the scent.
The film, which opened in the UK yesterday, has attracted a maelstrom of controversy for its violence and brutality.
Gibson, who gambled $25 million (14 million) of his own money to make it, has been rewarded with more than $250 million in box office takings, but has had to defend himself against a tide of criticism accusing him of being antisemitic.
Leach’s confession, meanwhile, is not the first from a cinemagoer stricken by conscience after watching the film.
This month James Anderson, 53, walked into a police station in Palm Beach County, Florida, and owned up to a 2001 bank robbery that netted him $25,000.
According to a spokesman, Anderson told detectives: "I saw The Passion and that made my decision," he said. Miller added: "He sort of urged the detectives to see the movie too."