CLARKSBURG, W.Va. (AP) — A federal inmate in West Virginia was found guilty in the fatal stabbing of another inmate on Friday.

Stephen C. Crawford, 44, was formerly housed at USP Hazelton. Crawford was convicted in U.S. District Court on charges of voluntary manslaughter, assault with a dangerous weapon and assault resulting in serious bodily harm, prosecutors said in a statement.

Crawford faces up to 15 additional years in federal prison on the manslaughter charge and up to 10 years for each assault charge.

Court records show Crawford used a prison-made weapon to stab inmate Arvel Crawford multiple times. The two are not related.

Stephen Crawford’s attorneys said he acted out of self-defense. But prosecutors said the victim was unarmed and posed no threat to the suspect.

USP Hazelton gained notoriety when Boston gangster James “Whitey” Bulger was killed just hours after he was transferred to the federal penitentiary in 2018 from another lockup in Florida and placed in the general population.