Frank Oppenheimer(August 14, 1912 – February 3, 1985) was the brother of J. Robert Oppenheimer, and was a renown physicist who was the scientific director of the Manhattan project. He came under fire from McCarthy era paranoia, being labeled a communist. While he admitted to going to several meetings, he denied being a communist and defended his position as an American scientist and scholar.
Despite his claims, the label "communist" which followed him for the next 15 years prevented him from further study in physics, and he became a high school teacher in Colorado. Once the McCarthy furor died down, he moved to London, where he studied the History of Physics.