All the Money in the World” comes to the screen on Christmas Day carrying a wild backstory, as Kevin Spacey was replaced just weeks before the film’s debut.

But the film — which details the 1973 kidnapping of Paul Getty III — has dodged a more long-standing controversy, namely whether Getty was in any way complicit in the crime. The film takes the position that he was not. But now, a relative of the kidnappers has come forward to allege that the film gets it wrong.

Michael Mammoliti is an actor and a nephew of Saro Mammoliti, one of the main kidnappers. He grew up hearing his family’s version of the story, and for years has been attempting to produce his own film about the incident. He says that he and his family are incensed that “All the Money in the World” will now become the accepted version.

In recent weeks, he has hired a lawyer and is now threatening to sue the production company, Imperative Entertainment. The film takes some liberties with the truth, and Mammoliti contends that it slanders his family. Barry Rothman, Mammoliti’s attorney, cited several such departures from reality in a letter to Imperative. For example, in the film Getty manages to escape temporarily after setting a fire in the Calabrian hills.

“This never happened,” the attorney wrote. “It’s false, and if you are accusing our clients’ family of being criminals and showing them in that light, then you shouldn’t show them in a light of being ‘unsuccessful/stupid’ criminals that can’t keep a 16-year-old boy in check. They were great criminals.”

Saro Mammoliti is also depicted as owning a warehouse that manufactures counterfeit Fendi handbags. Mammoliti says this never happened. Mammoliti also takes issue with a scene in which one of the kidnappers betrays his mafia cohorts. Mammoliti contends that they would never do that.

The biggest factual problem, according to Mammoliti, is that “All the Money in the World” portrays Paul Getty purely as a victim of the kidnappers. The drama turns on his mother’s efforts to free him and the refusal of his grandfather, oil baron J. Paul Getty, to pay the ransom. Paul Getty ended up losing an ear in the ordeal. He was finally released after five months in captivity and the payment of $3 million.

According to Mammoliti, the true story is more complicated than what the film portrays.

“The kid planned his own kidnapping,” Mammoliti tells Variety. “It started off with great intentions. It was a quick way to make a buck on both sides. It turned into a mess because of the grandpa not wanting to pay.”

The film, he argues, “is a Wikipedia version of a movie. There’s no truth about it. It’s false. It’s a lie.”

The film is based on John Pearson’s 1995 book, “Painfully Rich,” which chronicles the ill fortunes of the Getty heirs. The chapter about the kidnapping is told largely from the point of view of Gail Getty, Paul’s mother.

Another book, “Uncommon Youth” by Charles Fox, was published in 2013. It is based on interviews with several people, including Paul Getty. In an epilogue, Fox relates an interview with Martine Zacher, Paul’s ex-wife, in which she contends that Paul came up with the kidnapping plot as a means to fund their filmmaking projects, but later changed his mind. Both the author and Paul Getty died prior to the book’s publication.

Mammoliti has been attempting to produce his own version of the film since 2013, when he earned $60,000 by appearing in a Samsung commercial. He hired a screenwriter, Robin Shushan, who interviewed several members of his family and delivered a draft. Mammoliti says that he has since tried to cobble together financing for the film, but his backers lost interest once “All the Money in the World” went into production.

In Rothman’s correspondence to Imperative, the attorney alleges that “All the Money in the World” borrows elements from the Shushan screenplay.

“You have taken facts and information from parts of the screenplay and have incorporated them into your own screenplay, and clearly the release and distribution of your motion picture will render our clients’ screenplay useless,” Rothman wrote.

Mammoliti tells Variety that his uncles are “furious” about the Imperative film.

Imperative declined to comment to Variety, saying the company does not discuss pending litigation. However, in a letter responding to Rothman, Imperative’s attorney Kelli Sager wrote that the Mammoliti family’s claims are “baseless.” In essence, she contends that it is difficult to defame people who have confessed to kidnapping and various other crimes.

“The items identified in your letter range from the innocuous to the absurd,” she wrote, citing in particular the Mammolitis’ boast of being “great criminals.” “None of these things conceivably gives rise to a claim for reputational harm.”

Sager also wrote that Imperative had acquired rights to an earlier adaptation of “Painfully Rich” authored by Shushan, which was originally developed for Universal about a decade ago.

“Any subsequent version of the screenplay she prepared would violate our clients’ rights, not the other way around,” Sager wrote.

David Scarpa wrote the screenplay for “All the Money in the World.” In an interview, Shushan says she had reviewed his script and determined that it did not borrow from the two versions she wrote.

“Not a word of it was used,” she says.

Shushan says she believes the account of the kidnapping in “Uncommon Youth,” and finds the “Painfully Rich” version to be “boring.”

“It’s just a wealthy family that gets targeted by the mean, bad, one-dimensional mafia,” she says. The truth, she says, is far more interesting. “It’s such a fascinating story. It should be a 10-part miniseries.”

Shushan says she likes Michael Mammoliti, but found him to be “naive about the way this works.”

“It’s a complicated thing,” she says. “You can’t just walk into Hollywood and make a movie because you have a good story.”

Instead of pursuing litigation, she suggests that he “make the version he thinks represents the real story. Make that movie. Just do it.”

But Mammoliti says his chance to tell his family’s side of the story has been ruined.

“They’re going to believe the bigger guy, even if mine is 100% true,” he says. “I took a shot as an artist. Somebody bigger than me that’s more powerful can come and fictionalize anything they want and destroy my project.”