John Edgar Hoover was the first Director of the Federal Bureau of Investigation of the United States. Appointed director of the Bureau of Investigation—predecessor to the FBI—in 1924, he was instrumental in founding the FBI in 1935, where he remained director until his death in 1972 at age 77. Hoover is credited with building the FBI into a large and efficient crime-fighting agency, and with instituting a number of modernizations to police technology, such as a centralized fingerprint file and forensic laboratories.
Late in life and after his death Hoover became a controversial figure, as evidence of his secretive actions became known. His critics have accused him of exceeding the jurisdiction of the FBI. He used the FBI to harass political dissenters and activists, to amass secret files on political leaders, and to collect evidence using illegal methods. Hoover consequently amassed a great deal of power and was in a position to intimidate and threaten sitting Presidents. According to President Harry S Truman, Hoover transformed the FBI into his private secret police force; Truman stated that "we want no Gestapo or secret police. FBI is tending in that direction. They are dabbling in sex-life scandals and plain blackmail... J. Edgar Hoover would give his right eye to take over, and all congressmen and senators are afraid of him".
Above all, I would teach him to tell the truth ... Truth-telling, I have found, is the key to responsible citizenship. The thousands of criminals I have seen in 40 years of law enforcement have had one thing in common: Every single one was a liar.