ANCHORAGE, Alaska (AP) — An Alaska man convicted of murder and serving a 60-year sentence has died.

The Department of Corrections says 38-year-old Antonio Roberson was pronounced dead shortly before 10 p.m. Monday at Providence Seward Medical Center.

Roberson was serving time at Spring Creek Correctional Center in Seward.

The department says a correctional officer discovered Roberson unresponsive in his cell during a routine security check at 8:50 p.m.

Responders attempted life-saving measures and Roberson was transported to the hospital, where he was pronounced dead.

Roberson had been imprisoned since 2002. He pleaded no contest that year to second-degree murder in the Anchorage stabbing death of Ronald Stevens.

The department says every prisoner death is investigated by its professional conduct unit, Alaska State Troopers and the state medical examiner's office.