In 1939, Whittaker Chambers identified Adler to then-Assistant Secretary of State Adolf Berle as a member of an underground Communist group in Washington, DC, the Ware group. Chambers correctly identified Adler as serving in the General Counsel's Office at the Treasury Department, from which, Chambers said, Adler supplied weekly reports to the Communist Party of the United States. In 1945, Elizabeth Bentley identified Adler as a member of the Silvermaster group. A 1948 memo written by Anatoly Gorsky, a former NKVD "rezident" in Washington DC, identified Adler as a Soviet agent designated "Sax." That agent, transliterated "Sachs (Saks)" appears in the Venona decrypts supplying information about the Chinese Communists by both Gorsky and the head of the US Communist Party, Earl Browder.