AdvertisementThe History Of The FBI's Secret 'Enemies' ListFebruary 14, 2012facebookEmailJ. Edgar Hoover was the first director of the FBI. He introduced fingerprinting and forensic techniques to the crime-fighting agency, and pushed for stronger federal laws to punish criminals who strayed across state lines. He also kept secret files on more than 20,000 Americans he deemed "subversive." (Library of Congress)