Within the U.S. the CIC , in collaboration with the Provost Marshal General and the Federal Bureau of Investigation ( FBI ) , carried out background checks on military personnel having access to classified material , investigations of possible sabotage and subversion , and allegations of disloyalty , especially those directed against Americans of Japanese , Italian or German ancestry . Despite the prohibitions in the delimitation agreement with the FBI , the CIC ended up devoting considerable effort to civilian investigations . As Volume 7 of '' The History of the Counter Intelligence Corps '' explains : " Espionage and sabotage , being enemy directed , involved more than one person . Usually there were a number in the chain extending from the agent in the United States back through cutouts and couriers to the enemy country . This inevitably involved civilians with military suspects and the case became connected with the FBI . The military aspect became minor , and major investigative effort was in the civilian community to locate the higher-ups who presumably were controlling more than one agent . " However the use of informants within the Army become politically controversial , and CIC was forced to curtail its activities . In particular , the CIC was ordered to cease its domestic investigations , to destroy its investigative records , and to ship its agents out to overseas theaters . The reason for this sudden and unprecedented expulsion has never been clarified . One leading theory was expressed in the official history of the Corps , “ the speed of these events left little doubt that someone — possibly Communists who still held key positions in government — was determined to halt CIC investigative activities in the United States . ” Another possible explanation is that the CIC mistakenly bugged the hotel room of Eleanor Roosevelt and incurred the President ’s wrath . In any event , the CIC protected the investigative records it had so painstakingly accumulated . According to Sayer and Botting ( p. 47 ) “ When the command was given to cease any investigations of known or suspected Communists and destroy all files on such persons immediately , eight of the nine Corps Area Commanders took the remarkable step of disobeying this order . ” According to the official history of the Corps , this information proved highly valuable in controlling communism : “ the information acquired by CIC from May 1941 to September 1945 regarding communism and its adherents played a major part in keeping communism under control in the United States ever since . ” CIC units were also involved in providing security for the Manhattan Project , including duty as couriers of fissionable bomb materials from Los Alamos , New Mexico to Tinian . They also operated in 1945 at the United Nations Organizing Conference in San Francisco , over which Alger Hiss presided as secretary-general . Three years later , when Alger Hiss was accused of being a Communist and filed a libel suit against his accuser , his lawyers unwittingly hired an undercover CIC Special Agent as their Chief Investigator to help prepare his libel suit
United Nations Organizing Conference
United Nations Conference on International Organization
Counterintelligence Corps