The most successful field offices gather information predicating full investigation through a solid intelligence base that includes public source information and official records, liaison with officials and agencies, and information from informants and cooperative witnesses. Public corruption investigations require teamwork between the FBI and the U.S. Attorney's Office. The manner and direction of investigation should correspond to a prosecutive plan. In general, the Federal grand jury is a key resource in corruption investigations. Other effective investigation techniques include the use of supervised cooperative witnesses and controlled payoffs and bribes to public officials. The majority of public corruption cases fall within the FBI's White-Collar Crimes Program, where a variety of legislative, municipal, and law enforcement corruption have been identified, primarily in major cities. Other corruption investigations have fallen under the aegis of the Organized Crime Program and the Drug Program.