Dierkop married Joan Addis in 1958. They had a daughter and a son.
He was cast in two George Roy Hill films, and played an outlaw both times — as "Flat Nose Curry" in Butch Cassidy and the Sundance Kid (1969), he played a member of the Hole in the Wall Gang, and as "Floyd" in The Sting (1973), he acted as a bodyguard to Robert Shaw's New York gangster/griftee, Doyle Lonnegan. He is best known for playing Detective Pete Royster on the television series Police Woman between 1974 and 1978.
