An autopsy has determined what killed a Waterloo man. The Iowa State Medical Examiner’s office in Des Moines has ruled the death of Jason Gage a homicide. Preliminary results of the autopsy, conducted by Doctor Jeri McLemore on Tuesday, show the 29-year-old Gage died of severe injuries to the head. Police found Gage dead in his downtown apartment late Monday night. 23-year-old Joseph Lawrence of Cedar Falls was arrested Tuesday morning on a first-degree murder charge. Police say Lawrence confessed to the murder. Authorities have not revealed a possible motive. Lawrence remains in the Black Hawk County Jail on a one million dollar bond.