High Quality Content by WIKIPEDIA articles! Theodore Alvin Hall (October 20, 1925 – November 1, 1999) was an American physicist and an atomic spy for the Soviet Union, who, during his work on US efforts to develop the first atomic bomb during World War II (the Manhattan Project), gave a detailed description of the "Fat Man" plutonium bomb, and of processes for purifying plutonium, to Soviet intelligence. His brother, Edward Hall was a leading rocket scientist who worked on ICBMs.