A man convicted of battery against three Douglas County corrections workers died in his cell at the El Dorado Correctional Facility, the Kansas Department of Corrections said in a news release Saturday morning.

Joshua Matthews, 38, was found unresponsive in his cell on Friday. Staff began life-saving measures immediately and continued after emergency services arrived, but were unsuccessful, the release states. The cause of death is pending an independent autopsy as the Kansas Bureau of Investigation and KDOC investigates.

Matthews was serving a 245-month sentence, or just over 20 years, for his convictions against the Douglas County workers.