Mugshot of Alphonse Capone following his 1930 arrest on charges of tax evasion
Contempt of Court Opinion (February 1931)
Transcript of Capone's Interview with Revenue Agents (April 17, 1931)
Letter from Frank Wilson to Chief of Treasury Department's Intelligence Unit updating the Capone investigation(March 27, 1931)(pdf)
Guy T. Helvering, Narrative for Treasury Department Describing Operations from 1919 to 1936 (pdf)
Denial of Certorari (United States Supreme Court, May 2, 1932)
Guy T. Helvering, Narrative for Treasury Department Describing Operations from 1919 to 1936 (pdf)