The Federal Bureau of Investigation (FBI) is the investigative arm of the United States Department of Justice. Based in the sprawling J. Edgar Hoover Building on Pennsylvania Avenue in Washington DC, this huge organisation employs 11,500 special agents and consumes an annual budget of $4.3 billion.

While the CIA’s responsibility is to alert the US to foreign threats, the FBI’s main duty is to monitor intelligence on US soil. Their primary concerns are terrorism, organised crime, drug trafficking, cyber-crime and high-finance dodgy dealings known as white-collar crimes. The FBI also liaises with other overseas law enforcement agencies in an attempt to stem global crime.

The Fed's history dates back to 1908, when nine detectives and a handful of accountants were hired to investigate a spate of land fraud in during a period of rapid expansion in the US. Since then the FBI has investigated countless cases and their hall of infamy includes: Al Capone, Bonnie and Clyde, and brutal bank robber, John Dillinger.