A man who says he was a member of Malcolm X's security detail the day the civil rights leader was assassinated in 1965 told reporters Tuesday he saw New York City police officers trying to prevent supporters from restraining a man thought to be involved in the killing.

Mustafa Hassan, who said he used to be a member of the Pan-Africanist organization that Malcolm X founded, made the claim at a news conference in New York.

The man being restrained, Hassan said, was Talmadge Hayer -- also known as Mujahid Abdul Halim -- who was later arrested and convicted in the killing.

Hassan told reporters Tuesday he believes there was a conspiracy between the New York City Police Department, the CIA and the FBI in Malcolm X's assassination.

CNN sought comment from the NYPD, the CIA and the FBI.

Hassan said he was never interviewed about what he witnessed.

The new allegation is a part of a multimillion-dollar federal action filed on behalf of Malcolm X's family by civil rights attorney Ben Crump in February. In his notice to the federal government, Crump accuses the FBI, the CIA and the NYPD of "fraudulent concealment of evidence surrounding Malcolm X's murder," according to a February news release.

Malcolm X, one of the most powerful voices in the fight against racism in the nation, was shot dead after he took the stage at the Audubon Ballroom in New York on February 21, 1965.

"The FBI had many informants in the Audubon Ballroom on that tragic day," Crump, who also represents Hassan, said at Tuesday's news conference. "We know that they withheld their information and would not let anybody know, sent a directive that nobody is to reveal our presence in the Audubon Ballroom where Malcolm X was assassinated."

"Not even the informants themselves were aware of who all was involved. That's why we are putting forth in our legal action that the government was involved in the conspiracy to kill Malcolm X," Crump said.

Hassan said he decided to come forward now after seeing online that the family of Malcolm X was seeking a financial settlement with governmental agencies for their alleged actions during the assassination.

In a signed affidavit read at Tuesday's news conference, Hassan said after Malcolm X was shot, he turned his attention "back to the man I had seen running away, knowing that he was in part responsible for what I witnessed."

"I would later see the same man outside as he was being beaten by Malcolm's followers while a group of policemen who suddenly showed up on the scene (were) asking is he with us while at the same time holding back Malcolm's followers from beating him," Hassan stated in the affidavit.

At Tuesday's news conference, Hassan and Crump shared a photo showing the moment Hassan reached out and grabbed Hayer's collar.

Hayer and two other men were convicted in 1966 for the killing and sentenced to life in prison. The two others -- Muhammad A. Aziz and Khalil Islam -- said they were innocent. Hayer acknowledged he took part in the assassination, but he maintained the innocence of the other two men.

In 2021, a judge vacated the convictions of Aziz and Islam. That came after a 22-month investigation by then-Manhattan District Attorney Cyrus Vance's office and lawyers for the men found that evidence of their innocence, including FBI documents, was withheld at trial.

Aziz was released from prison in 1985; Islam was released in 1987 but died in 2009 and received a posthumous exoneration.

Last year, New York City agreed to pay $26 million to settle lawsuits filed on behalf of Aziz and Islam.