Montgomery County Coroner Rick Broaddus said Wednesday that 26-year-old Christopher G. Nichol hanged himself with a bedsheet at Graham Correctional Center in Hillsboro.
Broaddus says Nichol's cellmate found Nichol after returning from the prison gymnasium. He says Nichol tied the bedsheet around the metal frame of a bunk bed.
Attempts at resuscitation failed and Nichol was declared dead at 7:33 p.m.
An Illinois Department of Corrections spokeswoman said late Tuesday the matter is under investigation. She did not respond to a request for comment Wednesday.
State records show Nichol was eight months into a six-year term from Marion County for aggravated criminal sexual abuse of a victim older than five.