(Reuters) - Three men accused in the beating death of one of Boston's most notorious mobsters, James "Whitey" Bulger, have reached plea deals with federal prosecutors over their roles in the 2018 killing inside a federal prison, according to court papers.

Fotios "Freddy" Geas, Paul DeCologero and Sean McKinnon will change their pleas to guilty after coming to agreements with prosecutors, according to court documents filed in the Northern District of West Virginia on Monday. The men also asked the court to schedule a sentencing hearing.

Details of the plea agreements were not disclosed in the court documents.

Federal prosecutors along with Nathan Chambers, an attorney for Geas, declined to comment when reached by email by Reuters. Lawyers for the other men were not immediately available for comment.

All three men were indicted with conspiracy to commit murder in August 2022, four years after Bulger's bloodied body was discovered wrapped in a sheet in his prison cell in a high-security federal prison in West Virginia.

Geas and DeCologero, who were also indicted with murder, were accused of striking Bulger multiple times in the head with a padlock wrapped in a sock. McKinnon, who allegedly acted as a lookout during the Oct. 30, 2018, killing, was also charged with making false statements to a federal agent.

Bulger lived a double life as one of Boston's most notorious mobsters while also acting as a secret FBI informant. He went on the run for 16 years after he was tipped off by his FBI handler about a pending racketeering indictment against him.

Bulger was captured in California in 2011. Two years later he was convicted for 11 murders and other offenses and was sentenced to life in prison.

He was 89 years old and five years into his term when he was killed. The murder took place hours after he had been transferred from a prison in Florida.

Confined to a wheelchair, Bulger was beaten so badly that blood was found coming from his ears, prison staff said at the time. Two men were seen on surveillance footage entering his cell, according to those accounts.

At the time of Bulger's death, Geas was serving a life term for the 2003 murders of Genovese crime family boss Adolfo "Big Al" Bruno and associate Gary Westerman. DeCologero was serving a sentence of life plus 25 years for murder, racketeering and firearms offenses.

McKinnon was serving an eight-year sentence for stealing guns from a Vermont firearms store. For at least part of that time, he shared a cell with Geas.

(Reporting by Brendan O'Brien in Chicago and Rich McKay in Atlanta; Editing by Michael Erman)