In 1957 and 1958, Dark guest starred in two episodes of David Janssen's crime drama, Richard Diamond, Private Detective, as the lead in "The Mickey Farmer Case" and then as Rudi Trekhala in "Widow's Walk". About this time, he also guest starred on John Bromfield's crime drama, U.S. Marshal. In 1957, he played Sgt. Al Zavala in four episodes of the syndicated crime drama, Code 3, with Richard Travis in the lead role of assistant Sheriff Rodger Barnett.