At 2059 Central time the airplane received substantial damage on impact with terrain during a visual approach. Night visual conditions prevailed; the pilot was fatally injured. Earlier, the on-demand cargo flight departed from Peoria, Ill., but returned without incident after the pilot reported that the airplane door came open. The flight then departed at 2031. Subsequently, the pilot reported a rough right engine but, while diverting back to Peoria, the pilot diverted to Bloomington and crashed while maneuvering to land. The pilot did not declare an emergency.