His best known films from the pre-McCarthy period of his career were Crossfire, for which he received a Best Director Oscar nomination, and Murder, My Sweet, the latter an adaptation of Raymond Chandler's Farewell My Lovely. Summoned to appear before the House Committee on Un-American Activities (HUAC), he refused to cooperate and was sent to jail. After spending several months behind bars, Dmytryk made the decision to testify again, and give the names of his fellow members in the American Communist Party as the HUAC had demanded. On April 25, 1951, Dmytryk appeared before HUAC for the second time, answering all questions. He spoke of his own Party past, a very brief membership in 1945, including the naming of twenty-six former members of left-wing groups. He explained how John Howard Lawson, Adrian Scott, Albert Maltz and others had pressured him to include communist propaganda in his films. His testimony damaged several court cases that others of the so-called "Hollywood 10" had filed.
For a time, Dmytryk moved to England, and Stanley Kramer hired him to direct a trio of low-budget films before handing Dmytryk The Caine Mutiny. He made films for major studios Columbia, 20th Century Fox, MGM and Paramount Pictures, including, among others, Raintree County, The Left Hand of God, The Young Lions, a remake of the Marlene Dietrich classic The Blue Angel, and The Carpetbaggers.
These films were made with expensive stars of the calibre of Humphrey Bogart, Clark Gable, Gene Tierney, Spencer Tracy, Elizabeth Taylor, Bette Davis, Montgomery Clift and Marlon Brando, but apart from the memorable Western Warlock (1959), which he also produced, his work had lost much of the emotional urgency and psychological thrust represented by his early film noir Crossfire.
After his film career tapered off in the 1970s, he entered academia and taught at the University of Texas at Austin, and at the University of Southern California. He wrote several books on the art of filmmaking (such as "On Film Editing") and lectured at various colleges and theaters, such as the Orson Welles Cinema. Dmytryk died in 1999, aged 90.