Federal Bureau of Investigation (FBI), division of the U.S. Dept. of Justice charged with investigating all violations of federal laws except those assigned to some other federal agency. The FBI has jurisdiction over some 185 investigative matters, among them espionage, sabotage, and other subversive activities; kidnapping; extortion; bank robbery; interstate transportation of stolen property; civil-rights matters; interstate gambling violations; and fraud against the government. Created (1908) as the Bureau of Investigation, it originally conducted investigations only for the Justice Dept. After J. Edgar Hoover became (1924) director of the Bureau of Investigation, Congress gradually added one duty after another to the jurisdiction of the bureau and reorganized (1933) it with wider powers as the Division of Investigation in the Dept. of Justice. Under Hoover's direction, it battled against such roving outlaws as John Dillinger and "Pretty Boy" Floyd as well as against the organized crime of the prohibition era. In 1935 it was designated the Federal Bureau of Investigation. The FBI played an important role in raising the standards of local police units through its FBI Academy.

During Hoover's final years as director (he served until his death in 1972), the bureau became highly controversial and was the frequent target of attack from a wide variety of liberal groups. During the Watergate affair it was revealed that the FBI had yielded to pressure from top White House officials, acting on behalf of President Richard M. Nixon, to halt their investigation of the Watergate break-in. The FBI subsequently cooperated with the White House "inquiry" into the break-in, which was actually attempting a cover-up, and FBI Acting Director L. Patrick Gray destroyed files belonging to one of the convicted Watergate conspirators, E. Howard Hunt. Gray resigned (Apr., 1973) after his role became public. In June, 1973, Clarence M. Kelley was named director. He was followed by William H. Webster (1978-87), William S. Sessions (1987-93), Louis J. Freeh (1993-2001), and Robert S. Mueller 3d (2001-).