Chambers, May 1942
From notes taken by the FBI on a statement Whittaker Chambers made to them in May 1942. The highlighted portion of the FBI memo reads:
Mr. WHITTAKER CHAMBERS advised that he was a member of the Communist Party from 1924 until the Spring of 1937 at which time he ceased connections with the Party. He stated that during approximately four years prior to his exit from the Party he was a member of the Underground Movement of the Communist Party, U.S.A. stationed in Washington, D.C.