Walter Walker, 41, is being held under tighter security after the incident at Limon Correctional Facility on Saturday.
Walker is serving a 140-year sentence for the 1997 killing of a bounty hunter in Denver.
Department of Corrections spokeswoman Katherine Sanguinetti said Walker stabbed two inmates in the dining hall during lunch.
One of those stabbed, Daniel Duran, 33, was pronounced dead after being airlifted to a Denver-area hospital.
Duran was serving life in prison without parole for a 2004 murder in Adams County.
A third inmate, 30-year-old Francisco Hernandez, suffered minor injuries and was transported to a Limon-area hospital.
Those three inmates were the only ones involved in the fight and guards used a pepper spray substance to control Walker, said Sanguinetti.
Sanguinetti would not identify the weapon used before consulting with investigators.
Walker is serving consecutive sentences for murder, robbery and kidnapping for events surrounding the killing of Melvin Gurule, a Louisville volunteer firefighter and part-time bounty hunter.
Gurule was shot in the back of the head as he attempted to apprehend Walker on Sept. 23, 1997.
The bounty hunter had been led to a crawl space in a home in the 1500 block of Lowell Boulevard by the mother of Walker's girlfriend.
Newspaper accounts at the time said that when Gurule's partner left to retrieve a flashlight, Walker began shooting at Gurule, who was unarmed.
Walker then carjacked a vehicle belonging to a family watching a soccer game and forced them to drive him to a home in Arvada, where he was found hiding under a bed.
A court date related to the recent killing has not been set, according to the Lincoln County Court.
Limon Correctional Facility is a level four security prison housing 963 inmates.
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