Wheeler is alleged to have passed these reports as well as handwritten and typewritten material of cable reports from the State Department and the OSS to Soviet intelligence. Wheeler is alleged to have provided information on the organization and policies of British intelligence services and furnished memoranda prepared by the Foreign Nationalities Branch of OSS on material relating to the particular racial groups and activities within the United States. These allegations, launched during McCarthyism resulted in no charges ever being brought against Wheeler, who contended that the charges of espionage were a response to his outspoken criticism of the failings of the American economic and political system. Beginning in 1944, the entire range of OSS planning documents on the postwar occupation of Germany are alleged to have been supplied to KGB head Pavel Fitin through Wheeler. Some observers considered Wheeler the most active operative within the Perlo group, and his complicity was alleged to have been corroborated by information exhumed from the NKVD archives in the 1990s. Wheeler allegedly appears in Venona as a Soviet source under the cover name "Izra". Wheeler continued to pass documents to the Soviet Union after the war. In November 1945 he sent information on various issues. This included a report on the Italian domestic political situation on the eve of elections in that country; a copy of the confidential report written by the military governor in the U.S. occupation zone of the USSR; OSS reports about current political events in the USSR; OSS weekly reports on political events in Europe and a State Department intelligence report on the Middle East. In the 1950s, Wheeler became a dairy farmer in Washington state because he was unable to find teaching work. Wheeler was subpoenaed as a hostile witness before federal grand juries in Washington, D.C., and San Francisco; his pregnant wife and four children milk the cows. He was also summoned three times before the House Un-American Activities Committee. His sister, Margaret Jean Schuddakopf, said that his courage and steadfastness was her beacon as she fought her own battle for the right to teach. He had a long and distinguished teaching career, despite constant harassment and "blacklisting". He taught at Yale University, at Franconia College in Franconia, New Hampshire, and at Brandon University in Manitoba, Canada. In 1938, Wheeler married Mary Lukes Vause, a fellow graduate of Reed College, a new mother, and the widow of his best friend, Clare Vause. Donald Niven Wheeler died age 89 on November 8, 2002, in Seattle, Washington.