Alaska State Troopers say a man who killed himself after confessing to multiple murders across the country died in his Anchorage jail cell after cutting a wrist and using bedding material to strangle himself.

Troopers say the state medical examiner hasn't determined what injury was the primary cause of Israel Keyes' death.

Keyes was found dead in his cell Sunday morning. Blood-soaked papers that appeared to have writing on them also were found, and have been turned over to the FBI.

Keyes was awaiting a March trial in the death of 18-year-old Samantha Koenig. Authorities say he abducted Koenig in February from the Anchorage coffee stand where she worked.

Investigators say Keyes sexually assaulted Koenig and strangled her, then left her body in a shed while he went on a cruise. They say he dismembered the body when he returned two weeks later.