WASHINGTON — The inmates charged in the 2018 prison killing of notorious Boston gangster James “Whitey” Bulger have reached plea deals with prosecutors.

Plea deals for Fotios “Freddy” Geas, Paul J. DeCologero and Sean McKinnon were announced Monday, six years after the 89-year old was bludgeoned with a padlock on the end of a belt.

Geas, a former Mafia hitman, and DeCologero, a Massachusetts gangster, were accused of repeatedly hitting Bulger in the head while McKinnon served as a lookout.

Documents said DeCologero told another inmate witness that Bulger was a “snitch” and would be killed as soon as he arrived at the unit.

Prosecutors in West Virginia federal court have asked the court to schedule hearings for the men to change their not-guilty pleas and to be sentenced, but details about the agreements for the three have not been disclosed.

Geas and DeCologero, were originally charged with murder and conspiracy to commit first degree murder. McKinnon was originally charged with conspiracy to commit first-degree murder and making false statements to a federal agent.

In 2013, Bulger was convicted in a string of 11 killings and dozens of other crimes over decades in the mob, some of the crimes allegedly committed while he was an informant for the FBI.

Bulger was killed within hours after being transferred from a Florida lockup to USP Hazelton and placed in the general population. The move to put Bulger in the general population was criticized by experts and guards at the facility who had been complaining about violence and understaffing.

A Justice Department investigation in 2022 determined many management failures, widespread incompetence and flawed policies at the Bureau of Prisons set the stage for the killing. No malicious intent was cited in the report.

DeCologero, who was in an organized crime gang led by his uncle in Massachusetts, was convicted of buying heroin that was used to try to kill a teenage girl his uncle wanted dead because he feared she would betray the crew to police. The heroin didn’t kill her, so another man broke her neck, dismembered her and buried her remains in the woods, court records say.

Geas was an enforcer for the mob, but because of his Greek heritage was welcomed as a full fledged member of the Italian organization. He and his brother were sentenced to life in prison in 2011 for their participation in several gang-related violent crimes.

McKinnon had been on federal supervised release after serving prison time for stealing guns from a firearms dealer when he was arrested on charges in Bulger’s killing.