A Tri-City inmate died after being found unresponsive in his cell at the Washington State Penitentiary last week.
The Walla Walla Union-Bulletin reports Keenan Michael Thomas, 27, was due to be released from prison in 2022.
Thomas began serving a five-year sentence in March after being convicted of violating domestic protection orders and two counts of assault in Benton and Franklin counties.
Prison staff and paramedics attempted lifesaving measures but he could not be revived.
A critical incident review and autopsy will be requested, the prison said.