DENVER -- A federal prison inmate convicted of killing a cellmate and using his intestines to taunt guards was spared execution when the jury said Friday it could not unanimously agree on the death penalty.

William Sablan, 42, faces life in prison without parole at his April 18 sentencing hearing, said Jeff Dorschner, a spokesman for the U.S. attorney.

Sablan was convicted of first-degree murder last month in the death of Joey Jesus Estrella, 33. He was also the first federal inmate to face a possible death sentence since Timothy McVeigh.

The jury that convicted Sablan had been deliberating his sentence for three weeks. Jurors were not asked in court Friday how many favored the death penalty for Sablan, but all agreed they could not reach a unanimous decision for execution.

"After reasonable efforts, we are unable to unanimously agree upon a sentence," the jury said.

Because the jury deadlocked, the court will sentence William Sablan to life imprisonment.

Sablan and his cousin, Rudy Sablan, 37, were accused of killing Estrella Oct. 10, 1999, after a night of drinking and fighting in the cell they shared at the federal penitentiary in Florence.

Guards videotaped Sablan and his cousin during the incident.

Defense attorneys argued that William Sablan had a history of mental illness, brain injuries and post-traumatic stress disorder that left him unable to control his impulses and deliberately kill Estrella.

Troy A. Eid, United States Attorney for the District of Colorado issued the following statement after the verdict was read:

"Justice is served because William Sablan will now spend the rest of his life behind bars. He is a menace to society, and I don't say that lightly. His conditions of confinement must mirror the extreme danger he will continue to pose to the people who live and work around him.

"This means that Mr. Sablan must be closely supervised so that he presents the least possible risk to the safety of correctional officers, staff and other inmates.

"I would like to thank Assistant United States Attorneys Brenda Taylor and Phil Brimmer, as well as the US Attorney's Office staff, the FBI agents, the Bureau of Prisons staff, and law enforcement officers in Saipan who worked on this case."

Rudy Sablan also faces a first-degree murder charge. His trial date has not been set.