From the US Dept of Justice : Organization, Mission & Functions Manual: Attorney General, Deputy and Associate
The position of Attorney General was created by the Judiciary Act of 1789. In June 1870 Congress enacted a law entitled “An Act to Establish the Department of Justice.” This Act established the Attorney General as head of the Department of Justice and gave the Attorney General direction and control of U.S. Attorneys and all other counsel employed on behalf of the United States. The Act also vested in the Attorney General supervisory power over the accounts of U.S. Attorneys and U.S. Marshals.
The mission of the Office of the Attorney General is to supervise and direct the administration and operation of the Department of Justice, including the Federal Bureau of Investigation, Drug Enforcement Administration, Bureau of Alcohol, Tobacco, Firearms and Explosives, Bureau of Prisons, Office of Justice Programs, and the U.S. Attorneys and U.S. Marshals Service, which are all within the Department of Justice.
The principal duties of the Attorney General are to: