In late July , Special Agent Melvin Purvis, the Director of Operations in the Chicago office, received a tip on Dillinger's whereabouts that paid off when Dillinger was located, ambushed, and killed by Bureau agents outside the Biograph Theater. Howard , a civil rights leader from Mound Bayou, Mississippi. Hoover immediately changed tack, and during the next five years, the FBI investigated organized crime heavily. Johnson seated, foreground confers with background L-R: During the s through mids, he seemed to ignore organized crime of the type that ran vice rackets such as drugs , prostitution , and extortion. Jackson's successor at the post of Attorney General, Francis Biddle , did turn down Hoover's requests on occasion. Hoover's practice of violating civil liberties for the sake of national security has been questioned in reference to recent national surveillance programs. American Mafia[ edit ] During the s Hoover persistently denied the existence of organized crime , even while there were numerous shootings as a result of Mafia control of and competition over the Prohibition -created black-market. On May 3, , Nixon appointed L. These included those of Machine Gun Kelly in , of Dillinger in , and of Alvin Karpis in , which led to the Bureau's powers being broadened. One whom he often commended for particular effectiveness was the conservative sheriff of Caddo Parish, Louisiana , J. After The Washington Post broke a story in January , Kelley searched and found them in his outer office. Jackson left it to Hoover to decide how and when to use wiretaps, as he found the "whole business" distasteful. Many of these criminals frequently made newspaper headlines across the United States, particularly John Dillinger , who became famous for leaping over bank cages, and repeatedly escaping from jails and police traps. Hoover's moves against people who maintained contacts with subversive elements, some of whom were members of the civil rights movement , also led to accusations of trying to undermine their reputations. Edgar Hoover's name on the FBI building is a stain on the building.