Federal Bureau of Investigation

The Federal Bureau of Investigation, or F.B.I., is a governmental agency belonging to the United States Department of Justice serving as both federal criminal investigative body and an internal intelligence agency.

Plot
Throughout the series, there are various F.B.I. members shown, each playing varying roles. The most notable first role they played was when twelve F.B.I. agents were sent to Japan to investigate the Kira murders, including F.B.I. agent Raye Penber, who was investigating Light Yagami, a prime suspect in the case.

Light ends up tricking Penber into showing him his F.B.I. identification card, revealing his name. With this information, Light later contacts Penber via phone, telling him that he is Kira and proving this by killing someone. He then threatens Penber, ordering him to get onto a train and pick up an envelope waiting for him there. Penber is instructed to write down the names of all the FBI agents in Japan, and he does so, unaware that he is actually writing their names on a piece of paper from the Death Note, killing them all.

Having had all their agents in Japan die, Steve Mason of the F.B.I. states that his organization refuses to cooperate with L any further on the Kira investigation, instead backing out.

Later on, after the timeskip, Steve Mason decides to work on the case again, working with Near to create an organization known as the Special Provision of Kira, which consisted of members of the F.B.I. The majority of the S.P.K. members were later killed by the Death Note.