Federal Bureau of Investigation

The Federal Bureau of Investigation was a pre-War intelligence and security service of the United States principally for federal law enforcement under the Department of Justice.

Background
Besides federal law enforcement, the FBI before the war also had secret projects in developing military refrigerators and confiscating and marking seditious books and magazines for burning.

Appearances
The Federal Bureau of Investigation is mentioned in Fallout, Fallout: New Vegas and in the Fallout 76 Wastelanders update.