He also appeared in the 1988 pilot episode of Law & Order, "Everybody's Favorite Bagman", as District Attorney Alfred Wentworth. By the time the show was picked up in 1990, however, Thinnes was contractually obligated to another TV series, and so his character was replaced with D.A. Adam Schiff, played by Steven Hill. Thinnes made two appearances in The X-Files as Jeremiah Smith, an alien rebel with healing and shape-shifting abilities.