Appreciated for his role as John Shaunessy in the 1979 Dustin Hoffman feature Kramer vs. Kramer as well as for his portrayal of Johnny Tracy in the 1953 sports activities movie Roar from the Group, Duff appeared in various other films from the 1940s, ’50s, ’60s, and ’70s. After graduating from senior high school in Seattle, Washington, he offered in World Battle II being a radio serviceman with america Army Atmosphere Corps. He made an appearance in his debut film, Brute Power, in 1947. His tv appearances include visitor star roles for the Golden Women, The Rockford Data files, and Murder, She Wrote. Carrying out a romantic relationship with film superstar Ava Gardner, Duff wedded the British-born celebrity and filmmaker Ida Lupino. He and Lupino welcomed a girl called Bridget in 1952 and separated in the middle-1960s; after his divorce from Lupino was finalized in 1984, Duff wedded Judy Jenkinson. Through the past due 1940s and early 1950s, he starred within a radio crisis series predicated on the detective books of Dashiell Hammett.