The Federal Bureau of Investigation (FBI) was formed in 1908, and over the course of the 20th century it played a key role in investigating the most serious crimes committed in the United States.
With a reputation for working on some of the most complex and perplexing cases ever to cross the desks of law enforcement, in the 21st century the FBI continues to go about its important work.
Check out this gallery to learn about some of the biggest FBI cases of the 20th century.