WATCH MORE ON FOX NATION'S 'RIDDLE: THE SEARCH FOR JAMES R. HOFFA' "Suspects Outside of Michigan: Francis Joseph "Frank" Sheeran, age 43, president local 326, Wilmington, Delaware.

Sheeran claimed he was responsible for the murder of former Teamsters boss Jimmy Hoffa in 1975. Here, finally, was the true story behind one of the most infamously unsolved crimes in American history.

Mafia killer Frank Sheeran said he tried to alert union activist Jimmy Hoffa (pictured) that something was wrong before he fired two shots into the back of his dear friend's head.

Sheeran originally made this confession in Charles Brandt’s 2004 book “I Heard You Paint Houses: Frank ‘The Irishman’ Sheeran and Closing the Case on Jimmy Hoffa,” insisting he shot ...

Frank Sheeran’s Interesting History Pertaining To The Hoffa Hit. That chain of events, which comes from narrative “I Heard You Paint Houses” claims to be the truth, has been disputed by many ...

In 2004 he led the Fox News investigative team that uncovered new evidence in the murder of Jimmy Hoffa, based on the claims of hit-man Frank Sheeran. Click here for more information on Eric Shawn ...

"The Irishman" is based off the real life and true events of Frank Sheeran, played by Robert DeNiro. But not everyone buys his story of killing Jimmy Hoffa, played by Al Pacino, in 1975.

The big man came into view at the other side of the bar, a glass of red wine in his hand, a 6-foot-4 inch, 250-pound hulk. Frank Sheeran — known as “Big Irish,” the Teamsters honcho, the legend.

Sheeran allegedly shot his friend Hoffa in the head after luring him to a house in Detroit. Al Pacino as Jimmy Hoffa (left) and Robert DeNiro as Frank Sheeran in Martin Scorsese’s new film ...

The house where Frank Sheeran claimed to have shot Jimmy Hoffa, which was investigated by the FBI in 2005. Photo: Bill Pugliano/Getty Images. This is one explanation for Hoffa’s disappearance ...

Frank Sheeran, left, was a former president of Wilmington's Teamsters Local 326 who claimed to kill Jimmy Hoffa in a mob assassination in 1975. Robert De Niro, right, plays Sheeran in the movie ...