Donald Nivan Wheeler was employed by the Office of Strategic Services from 1941 to 1946. Wheeler was a member of Elizabeth Bentley’s Perlo group of spies and appeared in Venona as a Soviet source under the cover name "Izra". The Office of Strategic Services was a United States intelligence agency formed during World War II. It was the wartime (but not direct) precursor to the Central Intelligence Agency. ... According to Douglas Linder [1], Elizabeth Terrill Bentley, one of the most interesting witnesses to take the stand in the trial of Julius and Ethel Rosenberg, the so-called Red Spy Queen. ... Victor Perlo was a member of the Ware group, and later headed a Washington DC cell of Soviet operatives. ... The VENONA project was a long-running and highly secret collaboration between the United States intelligence agencies and the United Kingdoms MI5 that involved the cryptanalysis of Soviet messages. ...
Source
Harvey Klehr, John Earl Haynes, and Fridrikh Igorevich Firsov, The Secret World of American Communism (New Haven: Yale University Press, 1995)
Allen Weinstein and Alexander Vassiliev, The Haunted Wood: Soviet Espionage in America--the Stalin Era (New York: Random House, 1999)