One of the top legal scholars in the nation who held one of the highest positions in the U.S. Department of Justice and oversaw the legality of the actions of the FBI is now taking the bureau to task about the way it handled the investigation of Jimmy Hoffa.

"The main reason I say that they have been wrong is because that they now acknowledge to me -- many of them on the record in my book -- that they made a mistake about Chuckie forty years ago," Jack Goldsmith said about longtime Hoffa case suspect Chuckie O'Brien, his stepfather.

Goldsmith, who appeared on "America's News HQ" on Sunday, used his legal background and access to voluminous government files while writing "In Hoffa's Shadow, A Stepfather, a Disappearance in Detroit, and my Search for the Truth," his book about the case. He is the Henry L. Shattuck professor of law at Harvard University Law school, and served in the administration of President George W. Bush as an assistant United States attorney general.

Goldsmith headed the Department of Justice Office of Legal Counsel, the department that advises the president and executive agencies about the legality of governmental policies, and the FBI came under his purview.

The FBI has long believed O'Brien was driving the car that picked up Hoffa from the parking lot at the Machus Red Fox in Bloomfield Hills, Mich., on July 30, 1975, the day he disappeared. O'Brien has denied any involvement, despite the suspicions of Hoffa's family.

O'Brien was called the "foster son" of Jimmy Hoffa and grew up with Hoffa's daughter Barbara and son James P. Hoffa, the current International Brotherhood of Teamsters president.

The exclusive investigation into Hoffa's disappearance is part of our second series of "Riddle: The Search for James R. Hoffa," which is now available on the streaming service, Fox Nation. The series has uncovered new evidence and has raised new questions about once held beliefs regarding Hoffa's fate.

"The reasons that they think they were wrong is that they concluded that it was practically impossible for him to have actually been at the Machus Red Fox to pick up Hoffa at the time he was alleged to have done so, that a lot of the circumstantial evidence which seemed so probative at the time now seems to be the opposite," Goldsmith said. "A lot of the circumstantial case fell apart, they found reasons to think that he couldn't have been there, and they developed a different theory of the case and different evidence that pointed in a different direction...Chuckie was not there that day."

Goldsmith also took issue with the current Martin Scorsese - Robert De Niro film "The Irishman," which recounts the story of mobster Frank "The Irishman" Sheeran, who claims that he shot Hoffa. Goldsmith said that the story is false.

Sheeran claimed that he was in the passenger seat of the car that picked up Hoffa to take him to his death and that O'Brien was behind the wheel.

"There is absolutely zero evidence of that," argued Goldsmith, who called the claim "preposterous."

DeNiro has said that he believes Sheeran and has defended the film, but Goldsmith called Sheeran's story a "fictional confession."

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"The bottom line is that there is no evidence to support it, there are a lot of reasons to think Sheeran couldn’t have been involved and of all of the many of the FBI investigators who over the decades covered the case that I spoke to, agreed that he couldn’t have been involved."

As for his stepfather, Goldsmith said being considered a Hoffa suspect has loomed over him unfairly far too long.

"It's been terrible for him, it ruined his life basically, to have been accused from the beginning and to be accepted in the public mind," he said. "It's been devastating to him and terribly dishonorable. It ruined his reputation."

He said the FBI backed off sending him a letter that would exonerate O'Brien.

Goldsmith said he hopes the government will "clarify what they think about the Sheeran movie and the Sheeran book. They have a lot of information that's never been made public that could bring a lot of clarity to this case and I hope that they reveal it."

Fox Nation has called for the government to release the parts of the FBI's Hoffa files that remain secret to this day. Department of Justice documents seen by Fox Nation name Hoffa's killer as New Jersey Genovese crime family hitman Salvatore "Sally Bugs" Briguglio. However. much of the information in the files is redacted and is still being withheld from the public. Goldsmith is also calling on the government to release the files.

"The FBI knows a lot more than they have reported," he contended.

The Hoffa family also supports releasing the files so that they can finally learn the truth.

"I feel terrible for the Hoffa family. They've had to deal with this case and the circus around this case and the accusations about the case for 44 years," Goldsmith said. "It's been brutally difficult for them, I'm sure. And I'm sorry that they still have to go through it."

Fox Nation requested comment from the FBI about Goldsmith’s claims but has yet to hear back.

To watch all of “Riddle: The Search for James R. Hoffa,” go to Fox Nation and sign up today.

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