John Edgar Hoover served from 1924 to 1972 as the director of the Federal Bureau of Investigation (FBI). As its first director, Hoover molded the FBI into his image of a modern police force. He promoted scientific investigation of crime, the collection and analysis of fingerprints and the hiring and training of professional law enforcement agents. Though much of what Hoover accomplished during his long tenure was exemplary, his use of counterintelligence techniques went beyond the collection of criminal information to include building dossiers on prominent lawmakers and citizens. Over time his rigid morality and anti-Communism dominated the FBI, forcing agents to follow the Hoover line or be drummed out of the agency. By the 1960s Hoover's power was immense, yet the civil rights and antiwar movements would do much to discredit his tactics. Since his departure the FBI has sought to purge this part of his legacy from the...