The assassination of Malcolm X is getting reinvestigated by the Manhattan district attorney's office after he was murdered 55 years ago.

More than half a century ago, the civil rights activist got gunned down in Manhattan's Audubon Ballroom. A new Netflix mini-documentary called Who Killed Malcolm X? prompted the New York City district attorney's office to analyze those convictions and reinvestigate the person responsible for murdering Malcolm X.

The documentary examines conspiracy theories surrounding the death of Malcolm X, one of them being that X was set up by the FBI and the assassination was carried out by white nationalists, The Guardian reported. 

Thomas Hagen, Thomas Johnson and Norman Butler were the only members of the Nation of Islam to be convicted. 

"There's been considerable doubt about the guilt of two of the three men convicted in the assassination of Malcolm X," Phil Bertelsen and Rachel Dretzin, co-directors and producers of Who Killed Malcolm X?, said, ABC News reported.

"The primary reason is that the only assassin (Thomas Hagan) caught at the scene and carrying a weapon, said that the other two men — Thomas Johnson and Norman Butler — were innocent at the trial," Bertelsen and Dretzin said via email to ABC News. "Ten years later, when attorney William Kunstler attempted to reopen the case, Thomas Hagan maintained the innocence of Johnson and Butler, and named the men he said were the real accomplices in a sworn affidavit."

The streaming series focuses on the lack of evidence against Bulter and Johnson. The Innocence Project, a nonprofit organization that helps to exonerate wrongly convicted people, found out that there are obtained FBI documents in favor of Hagan's defense for Butler and Johnson that have never been used.

The documentary instead points to four Nation of Islam members from Newark, New Jersey, one of whom was William Bradley. Bradley, who changed his name to Al-Mustafa Shabazz, appeared in an ad for now-Sen. Cory Booker’s mayoral campaign. Booker told the New York Times that he knew Shabazz well but didn't know about his true identity. Shabazz died in 2018. 

Lawyers for Butler are hopeful that the Manhattan DA, Cyrus R. Vance Jr., will clear his name.

In response to the documentary, the DA's office said that it will review whether to reinvestigate the case.

Peter Casolaro, one of the prosecutors conducting the review, is responsible for dismissing the convictions of the five men wrongfully imprisoned in the Central Park Jogging Case in 1989.