When Dr. Spencer Truman is murdered, Rex, who ran into Michael at the hospital on the night of Spencer Truman's murder, believed Michael was the one who stabbed Spencer to prevent him from revealing the paternity of Tommy to Todd Manning (Spencer had kidnapped Tommy, who was really the child of Todd Manning and Margaret Cochran on the day of his birth); Michael believed Rex had committed the murder for the same reason.
Upon Dr. Spencer Truman's death, Rex, who met Michael at the hospital that night, thought Michael was the killer who silenced Spencer to prevent him from revealing Tommy's true parentage to Todd Manning (Spencer had taken Tommy, who was actually Todd and Margaret's son, on the day of his birth); Michael believed Rex had committed the murder for the same motive.