Complex sentence: He also served in Austria (1952-53), and in Washington, D.C. (1953-57) and in 1954, he testified in the Dr. Robert Oppenheimer security investigation.
Split into simpler sentences: He also served in Austria (1952-53), and in Washington, D.C. (1953-57). In 1954, he testified in the Dr. J. Robert Oppenheimer security investigation.