Federal Bureau of Investigation
An agency of the Department of Justice, the Federal Bureau of Investigation (FBI) is charged with criminal investigation of federal crimes and with internal security matters. Formed in 1908, the FBI now has over 35,000 employees and a budget of $7.9 billion. During World War II, the FBI investigated and arrested selected Japanese residents in the U.S. after the attack on Pearl Harbor and monitored and investigated Japanese Americans throughout the war, often at odds with the War Relocation Authority .
Founding and Early Years
The Bureau of Investigation was formed as a ten-member force in 1908 by Attorney General Charles Bonaparte in reaction to a spate of new federal laws—mostly involving changes in interstate business and transportation brought on by the industrial revolution—when entreaties for such a force were turned down by Congress. The bureau's influence and budget grew steadily in the following decades, first with greater calls for internal security during and immediately after World War I and later with the rise of notorious gangsters and the perception of a national crime wave in the 1930s. Between 1932 and 1939, the Federal Bureau of Investigation—its name was changed in 1935—saw its budget and personnel more than double. FBI director J. Edgar Hoover was appointed in 1925 and would hold that position for nearly five decades.
Intelligence Work and World War II
The impact of World War II saw a dramatic increase in the FBI's size and influence, with the agency going from 898 agents in 1940 to 4,886 in 1945.  Citing the threats from possible fifth column activity, Hoover began a secret custodial detention program in 1939 and also got presidential approval for secret wiretapping. He also battled other governmental entities to secure for the FBI the major role in domestic intelligence work, going so far as to monitor members of the Dies Committee —whom he viewed as rivals—and leak damaging information about them. He also used a presidential statement issued in 1939 to broker a deal with the Office of Naval Intelligence and the Military Intelligence Division giving the FBI the main responsibility for all investigations of "subversive movements" involving civilians. 
The FBI played a number of roles in the Japanese American story during World War II. The first involved prewar surveillance and apprehension of community leaders after the attack on Pearl Harbor. Through their custodial detention program , the FBI worked with the ONI and army to put together custodial detention/ABC lists of those to be detained in event of war. On December 7, Robert Shivers , the head of the FBI office in Honolulu, called Hoover during the attack with bombs still exploding in the background. Hoover authorized the FBI to arrest and detain all those on the ABC lists regardless of classification. The FBI also engaged in conducting warrantless random raids of Japanese American homes in the weeks after the attack on Pearl Harbor. The image of grim-faced FBI G-Men arresting Issei community leaders and ransacking Japanese American households is a frequently recalled by Japanese Americans remembering that time.  It was the FBI who arrested those few Japanese Americans who disobeyed evacuation orders on the West Coast. In Hawai'i, the FBI continued its surveillance and interrogations of Japanese Americans throughout the war, though Shivers eventually built close ties with Nisei leaders and is often credited with helping to prevent the mass removal of Japanese Americans in Hawai'i. Director Hoover famously opposed the mass removal of West Coast Japanese Americans, feeling that his agency had successfully identified and arrested those who posed any kind of threat.
After West Coast Japanese Americans had been removed to inland concentration camps, the FBI monitored activity in the camps. Hoover and the FBI feuded with Dillon Myer and the War Relocation Authority over their administration, feeling that the latter were lax on security and went easy on troublemakers. When Myer asked Hoover to conduct the loyalty investigations for the WRA, Hoover refused.  Meanwhile, FBI special agents entered the camps without permission of the WRA officials, cultivating a network of informants in the camps. The FBI was slow to approve leave clearance applications and, in at least one case, stopped a WRA sponsored resettlement of families in Texas only because the area was isolated making it "almost impossible to observe the activities of Japanese" in an area having "strategic importance to the war effort." 
When Japanese American returning to the West Coast were confronted by terroristic activity , the FBI was assigned to protect them.
For More Information
Commission on Wartime Relocation and Internment of Civilians. Personal Justice Denied: Report of the Commission on Wartime Relocation and Internment of Civilians . Foreword by Tetsuden Kashima. Seattle: University of Washington Press, 1997.
Drinnon, Richard. Keeper of Concentration Camps: Dillon S. Myer and American Racism . Berkeley: University of California Press, 1987.
Hayashi, Brian Masaru. Democratizing the Enemy: The Japanese American Internment . Princeton: Princeton University Press, 2004.
Muller, Eric L. American Inquisition: The Hunt for Japanese American Disloyalty in World War II . Chapel Hill: University of North Carolina Press, 2007.
The FBI: A Complete Reference Guide, edited by Athan G. Theoharis with Tony G. Poveda, Susan Rosenfeld, and Richard Gid Powers. Phoenix: Oryx Press, 1999.
The FBI's official history can be accessed at http://www.fbi.gov/about-us/history .
- Athan G. Theoharis and John Stuart Clark, The Boss: J. Edgar Hoover and the Great American Inquisition (Philadelphia: Temple University Press, 1988), 157.
- Theoharis and Clark, The Boss , 183.
- See for instance, Densho interviews with Eiichi Edward Sakauye (segment 17; densho id: denshovh-seiichi-01-0017) or Nelson Takeo Akagi (segment 10, densho id: denshovh-anelson-01-0010.)
- Richard Drinnon, Keeper of Concentration Camps: Dillon S. Myer and American Racism (Berkeley: University of California Press, 1987), 51.
- Brian Masaru Hayashi, Democratizing the Enemy: The Japanese American Internment (Princeton: Princeton University Press, 2004), 150.