Martin Scorseses The Irishman is set to make a bloody splash. Based on the book I Heard You Paint Houses, the 2004 work by prosecutor Charles Brandt, the film is based on the true stories of supposed mafia hitman Frank "The Irishman" Sheeran and his confessed killing of Jimmy Hoffa.

Scorsese frames his film using old, wheelchair-bound Sheeran (Robert De Niro). Sheeran recounts his rise from meat-packing WWII vet to confidant and hitman of the Bufalino crime family, an Italian-American crime syndicate active in parts of Pennsylvania. Sheerans ascent then takes center stage, and we watch as he meets union leader Jimmy Hoffa (Al Pacino), becomes his protection, and then later, apparently, murders Hoffa. The end.

While Scorseses adaptation seems to follow these real-life events closelyor, at least, these real confessionsthere are also a spattering of narrative liberties.

Heres what's true and what's not in The Irishman.

In July 1975, Jimmy Hoffa, former president of the Teamsters union, disappeared. Hoffa had by then served out a prison sentence for jury tampering. He maintained dubious financial connections with the Bufalino crime family and had been charged with fraud after using union pension funds as loans to organized crime members. Hoffas prison sentence had been commuted, however, and he was released in 1971. Back on the street, Hoffa tried to regain control over the union, angering organized crime families. And then he disappeared.

Which was about as much as anyone knew. That is, until a man considered just another low-bit mobster, Sheeran, took credit for the killing in 2003. He also took credit for other killings. Because, hey, why not.

Sheeran's confession may be where The Irishman is spinning yarns. Many people, including former Irish mob leaders, FBI agents, and persecutors, doubt Sheeran was capable of killing anyone . And after Sheeran confessed to the crimes, not even the police bothered to charge or arrest him.

Sheeran continues to be held as nothing more than a union thug, someone who, at worst, ordered the killings of union rivals. Still, Sheerans confession offered both a nice explanation for Hoffas disappearance, as well as an exciting story to go along with it.

In dramatizing Sheerans words, Scorsese likely isnt conceding to his account, and viewers are encouraged to take his testimony with a lot of proverbial salt. Part of what will make the film interesting is how well De Niro (as Sheeran) sells his tale. But be warned: nothing he says has been verified.

A common telling of Hoffa's murder goes something like this: After his release from prison, Hoffa started pissing off the mob, particularly Anthony Provenzano, who had taken over for Hoffa as head of the Teamsters union in Union City, New Jersey. Provenzano then arranged the killing with the help of the Detroit mob. Provenzanos man, Salvatore Briguglio pulled the trigger. Sheeran merely rode with Hoffa in a car to calm his nerves.

Sheeran, however, claimed that the Bufalino family organized the killing, and that it was he himself who carried it out, shooting Hoffa in an abandoned house.

But again, many journalists, investigators, and FBI agents, reject Sheerans claims . They also reject his other supposed confessions, including the killing of Joe Gallo. In a recent interview with Slate, Nicholas Gage, a New York Times reporter at the time of the killing, said I havent read the script of The Irishman, but the book on which it is based is the most fabricated mafia tale since the fake autobiography of Lucky Luciano.

Which is to say the source material for The Irishman could be just a bunch of malarkey. And maybe that's Scorsese's point.