J. Edgar Hoover (1895-1972), American criminologist and government official and director of the Federal Bureau of Investigation (FBI) for 48 years.

Hoover was born in Washington, D.C., on January 1, 1895, and studied law at George Washington University. In 1917 he was admitted to the bar, and in the same year he joined the staff of the U.S. Department of Justice. Two years later he was appointed a special assistant to the U.S. attorney general. In 1924 he was named head of the Bureau of Investigation of the Justice Department. In 1935, when the division became the Federal Bureau of Investigation, Hoover was made its director. He served under every president from Calvin Coolidge to Richard Nixon.

Hoover instituted many of the techniques and procedures that made the FBI famous for its efficient apprehension of criminals. During the 1930s he supervised the investigations that led to the capture of many criminals, including the bank robber John Dillinger. In World War II the counterespionage and antisabotage operations conducted by the FBI were successful in preventing interference by German and Japanese agents with the U.S. war effort. After the war, he led the bureau in an exhaustive series of investigations designed to curb subversive activities both within the federal government and in private industries and institutions.

Hoover was a controversial figure for many years. Critics accused him of abusing his power and exceeding the jurisdiction of the FBI. His contributions to the advancement of police technology, however, are undeniable. Hoover died May 1, 1972, in Washington, D.C. His writings include Persons in Hiding (1938), Masters of Deceit (1958), A Study of Communism (1962), and Crime in the United States (1965).