Newly declassified fbi files, supplemented by files of other agencies, provide new insight into the activities of Eastern European émigrés who had collaborated with the Nazis in the murder of Jews and other ethnic groups before relocating to the United States under the 1948 Displaced Persons Act. Many have concluded that the arrival and naturalization of war criminals in the United States was the fault of the Immigration and Naturalization Service, which has been portrayed as understaffed and even incompetent. Yet the INS was not as negligent as has been assumed. The FBI, as the nation's chief law enforcement agency, knew much about the criminal backgrounds of many émigrés, but it never acted on what it knew, nor did it assist other agencies that wished to act, including the INS.

The FBI's indifference must be understood in context. In the 1950s it was widely held that the threat to American security came not from Nazis or their collaborators, but from the Soviets and theirs. Communism had been a target of FBI operations since 1917, and such remained the case during World War II despite the FBI's surveillance of Nazi-related activities. Postwar FBI counterintelligence directed against Communism was similarly broad in scope.