CLARKSBURG, W.Va. (AP) A former Mafia hitman was sentenced to 25 years in prison Friday in the 2018 fatal prison bludgeoning of notorious Boston gangster James Whitey Bulger .

Federal prisoner Fotios Freddy Geas was sentenced in federal court in northern West Virginia after pleading guilty to voluntary manslaughter and assault resulting in serious bodily injury

Prosecutors said Geas used a lock attached to a belt to repeatedly hit the 89-year-old Bulger in the head hours after he arrived at the troubled U.S. Penitentiary, Hazelton, from another lockup in Florida in October 2018. Defense attorneys disputed that characterization, saying Geas hit Bulger with his fist.

Geas, 57, already was serving a life sentence for previous violent crimes. The Justice Department said last year that it would not seek the death penalty against him in Bulgers killing.

Bulger, who ran the largely Irish gang in Boston in the 1970s and 80s, also served as an FBI informant who ratted on his gangs main rival, according to the bureau. Bulger strongly denied ever being a government informant.

Bulger became one of the nations most wanted fugitives after fleeing Boston in 1994 thanks to a tip from his FBI handler that he was about to be indicted. He was captured at age 81 after more than 16 years on the run and convicted in 2013 in 11 killings and dozens of other gangland crimes.

Another Hazelton prisoner, Massachusetts gangster Paul J. DeCologero, was sentenced to more than four years in prison in August on an assault charge in Bulgers killing. Prosecutors said he acted as a lookout for Geas. A third inmate, Sean McKinnon, pleaded guilty in June to lying to FBI special agents. McKinnon was given no additional prison time and was returned to Florida to finish his supervised release. He had served a sentence for stealing guns from a firearms dealer.