Itaru Tachibana

USC PhD student Pedro Loureiro wrote that Tachibana's arrest by agents of the Federal Bureau of Investigation (FBI) "became the most publicized and sensational Japanese espionage case in the United States during 1941.

[6] Office of Naval Intelligence (ONI) employee Henry Claiborne, a lieutenant in the Navy, in early June of that year, gave notice to the Los Angeles office of the Federal Bureau of Investigation (FBI) that the ONI had begun monitoring Tachibana as the agency believed that he was acting as a foreign agent for Japan; the FBI chose not to open its own investigation while the ONI investigated.

[3] 11ND's district intelligence office also opened an investigation on Tachibana as it was suspecting he was trying to damage U.S. naval operations.

"[7] Initially the FBI was hesitant to pursue prosecution due to diplomatic issues as Tachibana was a known affiliate of the Japanese government.

[10] The files seized from Tachibana's hotel room also contained evidence implicating Charlie Chaplin's ex secretary Toraichi Kono, British War Hero Frederick Rutland, and other Japanese attachés such as Sadatomo Okada.

[13] He boarded the Nitta Maru on June 21 in San Francisco, which U.S. government officials forced him to do, and set sail for Japan.