McCarthyism & Red Scare
Klaus Fuchs (1911-1988) was a German-born atomic physicist who worked on the Manhattan Project, helping to develop the atomic bomb during World War II. He was also a Communist and a Soviet agent.
During his time working on the Manhattan Project, Fuchs conveyed top-secret information on the American atomic program to the Soviet Union. It remains unclear whether information gleaned from Fuchs's spying helped to accelerate the Soviet bomb program, which successfully detonated a nuclear device in 1949. Fuchs was arrested by British intelligence in 1950. He spent nine years in jail before being deported to Communist East Germany, where he lived until 1988.