16 July 1943 memo. Francis Biddle, Attorney General to Hugh B. Cox, Assistant AG and J.E. Hoover, FBI, declaring custodial detention lists “inherently unreliable” and stating they should not be used. Download: 16 Jul 1943 ltr Biddle_Custod_detention list
4 Jun 1942, FBI memo, Edward Tamm to Hoover — reports on N. J. L. Pieper meetings with Ennis and DeWitt
2 Jun 1942, FBI memo, Pieper (San Francisco Special Agent in Charge) to Hoover — report on meetings with General John DeWitt of the Western Defense Command and Edward Ennis, Director, Alien Enemy Control, Department of State.
J. Edgar Hoover to Major General Edwin Watson, 10 Dec 1941; Archival Document package “FDR and World War II,” Franklin D. Roosevelt Presidential Library — FBI report on number of Japanese, German, and Italian aliens in custody as of 9 December, 1941.