Chuck appears to be going the way of one of the detectives, Brian Rafe, on The Sentinel. He was originally the body double of Richard Burgi (Jim Ellison to you), started appearing onscreen whenever they needed a spare body in the background doing something, and then became regular, then with lines, and they couldn't be arsed to think up a new name for him since he was in all the production notes as 'Rafe'. Chuck Campbell is well on his way to having his onscreen name be 'Sgt Chuck Campbell'. It's how everyone refers to him, including the directors.