An inmate at a Kansas prison was found dead in his cell.

According to the Kansas Department of Corrections, Norton Correctional Facility resident Joshua Wilburn, 46, died unexpectedly on Tuesday. He was found unresponsive in his cell Tuesday afternoon. Staff began life-saving measures immediately and continued after emergency medical services arrived but were unsuccessful.

The cause of death is pending the results of an independent autopsy.

Per protocol, when a resident dies in the custody of the KDOC, the death is under investigation by the KDOC and the Kansas Bureau of Investigation. The investigation is ongoing.

Wilburn was serving an 18-month sentence for five counts of violating the Kansas Offender Registration Act stemming from convictions in Wisconsin.

The Norton Correctional Facility serves only adult males and has a capacity of 835 residents.