UMATILLA, Ore. (AP) — State prison officials say an inmate died unexpectedly early Saturday at Two Rivers Correctional Institution in Umatilla.

The Oregonian/OregonLive reports ( ) 61-year-old Richard Bradbury's death is under investigation by Oregon State Police.

Bradbury entered prison in 1994 and was serving a life sentence for aggravated murder and arson out of Marion County.

Oregon Department of Corrections officials say he was found unresponsive in his cell at 3:38 a.m. Saturday. Officials say he was pronounced dead less than an hour later after medical staff couldn't revive him.

Officials say state police investigation is standard in unexpected prison deaths.

Two Rivers houses about 1,800 men. This is the second unexpected death to occur at the facility this year.