The three daughters of slain Civil Rights-era leader Malcolm X are calling for the investigation into his murder to be re-opened, citing a deathbed confession from a former undercover police officer who said the NYPD and FBI conspired to kill the Black activist in 1965.

Three Nation of Islam members were convicted in the murder of Malcolm X (born Malcolm Little), which took place at Washington Heights’ Audubon Ballroom on February 21, 1965—exactly 56 years ago this Sunday.

But a letter unveiled at a Saturday news conference purports to be from Ray Wood, an undercover New York police officer at the time of the murder. Wood’s deathbed confession accused his NYPD supervisors of pressuring him to arrest Malcolm X’s security detail just prior to the fatal shooting.

“Under the direction of my handlers, I was told to encourage leaders and members of the civil rights groups to commit felonious acts,” he wrote.

Wood’s letter said his coercive efforts entrapped Malcolm X’s bodyguards and ultimately guaranteed the activist would not have door security at the Audubon Ballroom.

The letter, written by Raymond Wood, was authorised for posthumous release by a cousin.

Malcolm X was killed onstage, where he was hit with a sawed-off shotgun blast and multiple semi-automatic handgun rounds. Three gunman from the National of Islam were ultimately convicted in the murder: Thomas 15X Johnson, Norman 3X Butler, and Talmadge Hayer, also known as Thomas Hagan

Ray Wood’s cousin, Reggie Wood, was alongside Malcolm X’s daughters at the news conference this weekend. Civil rights attorney Ben Crump was also at the event held on the site of where the Audubon Ballroom once stood off 165th Street and Broadway in New York City. Crump’s law office issued a statement describing the press conference as a platform to “deliver new evidence regarding the assassination of Malcolm X to his daughters & the Manhattan DA” following Wood’s deathbed declaration.

The FBI has repeatedly declined to comment on the matter, and the NYPD has issued several statements saying it has “provided all available records” to the Manhattan District Attorney’s office.

The NYPD reiterated that the department is “committed to assist with that review in any way.”

Manhattan District Attorney Cy Vance last year announced he would review the convictions made in the 1965 case, which Malcolm X’s daughters have long held in suspicion as part of a law enforcement cover-up. The Manhattan District Attorney is working with representatives from the Innocence Project to analyze the decades-old convictions in the murder case.

Attorney Ray Hamblin, counsel for Malcolm X’s late widow, Dr. Betty Shabazz, described the push to re-open the murder investigation as an ongoing pursuit of “restorative justice.”