Who was the most successful Soviet spy involved in the Manhattan Project ?
Elizabeth Bentley — American spy for Soviet Union from 1938 until 1945 ; in 1945 she defected from Soviet intelligence and became a key informer for the U.S. Whittaker Chambers — admitted Soviet spy in the Ware Group ; testified against Alger Hiss Morris Cohen — convicted Soviet spy , subject of Hugh Whitemore 's drama for stage and TV " Pack of Lies " ; instrumental in relaying atomic bomb secrets to the Kremlin in the 1940s , eventually settling in Moscow where for decades he helped train Soviet agents against the West William Malisoff — ( Ph.D. ) alleged Soviet spy , purportedly transferred advanced technology to the USSR Isaiah Oggins — ( B.A. )