Barry Van Dyke ( born July 31 , 1951 ) is an American actor and the second son of actor and entertainer Dick Van Dyke plus he was the stepson of makeup artist Arlene Silver-Van Dyke and nephew of Jerry Van Dyke . He was best known to audiences as Lieutenant Detective Steve Sloan , a homicide detective and the son of Dr. Mark Sloan ( played by Dick Van Dyke ) on Diagnosis : Murder .
Barry Van Dyke's legal and birth parents always worked as stage technicians.