The Christian Investigations Bureau (CIB) is a Union of Christian States governmental agency belonging to the Christian States Department of Justice that serves as both a federal criminal investigative body and an internal intelligence agency (counterintelligence). Also, it is the government agency responsible for investigating crimes on Native American reservations in the Christian States under the Major Crimes Act. The CIB has investigative jurisdiction over violations of more than 200 categories of federal crime.

The bureau was established in 1908 as the Bureau of Investigation (BOI). Its name was changed to the Christian Investigations Bureau (CIB) in 1935. The CIB headquarters is the Woodie Building, located in Beaumont, Texas. The bureau has twenty-six field offices located in major cities throughout the Christian States, and more than 200 resident agencies in lesser cities and areas across the nation. More than 50 international offices called "legal attachés" exist in U.C.S. embassies and consulates general worldwide.