The death of an inmate at the Iowa State Penitentiary in Fort Madison has been ruled a suicide. Staff at the prison say 23-year-old Jeffrey Wittler was found unresponsive, completely covered by a blanket, in his cell Saturday morning.

A guard removed the blanket and discovered a plastic bag over Wittler’s head. The State Medical Examiner has determined the cause of death to be asphyxia due to suffocation.

Wittler started serving a 15 year sentence from Dickinson County in May of this year. He was initially charged with attempted murder after Spirit Lake Police said he assaulted his mother with a knife. Wittler was convicted of lesser charges.