Al Capone Mabel Walker Willebrandt recognized that mob figures publicly led lavish lifestyles yet never filed tax returns, and thus could be convicted of tax evasion without requiring hard evidence to get testimony about their other crimes. She tested this approach by prosecuting a South Carolina bootlegger. In 1927, the Supreme Court ruled in "United States v. Sullivan" that illegally earned income was subject to income tax; Justice Oliver Wendell Holmes Jr. rejected the argument that the Fifth Amendment protected criminals from reporting illegal income. The IRS special investigation unit chose Frank J. Wilson to investigate Capone, with the focus on his
Al Capone marked Capone's rule. Organized crime in the city had a lower profile once Prohibition was repealed, already wary of attention after seeing Capone's notoriety bring him down, to the extent that there is a lack of consensus among writers about who was actually in control and who was a figurehead "front boss". Prostitution, labor union racketeering, and gambling became moneymakers for organized crime in the city without incurring serious investigation. In the late 1950s, FBI agents discovered an organization led by Capone's former lieutenants reigning supreme over the Chicago underworld. After Capone was released from prison, he was referred to