Three men charged in the 2018 prison killing of notorious Boston gangster James “Whitey” Bulger have reached plea deals with prosecutors, according to court papers filed Monday.

The plea deals were disclosed nearly six years after the 89-year-old gangster, who spent almost two decades on the lam, was beaten to death in his cell at a troubled West Virginia prison.

Fotios “Freddy” Geas and Paul J. DeCologero were accused of repeatedly striking Bulger in the head while Sean McKinnon served as a lookout. An inmate witness told authorities that DeCologero said he and Geas used a belt with a lock attached to it to beat Bulger to death.

Prosecutors asked the court to schedule hearings for the men to change their not-guilty pleas and to be sentenced, though they didn’t provide further details about the plea agreements, which have not been filed in court.