A secret history of the United States government's Nazi-hunting operation concludes that American intelligence officials created a safe haven" in the United States for Nazis and their collaborators after World War II. The 600-page report, which the Justice Department has tried to keep secret for four years, provides new evidence about more than two dozen of the most notorious Nazi cases of the last three decades. It describes the government's ... pursuit of Dr. Josef Mengele, the so-called Angel of Death at Auschwitz. The report catalogs both the successes and failures of the band of lawyers, historians and investigators at the Justice Department's Office of Special Investigations, which was created in 1979 to deport Nazis. The report's most damning disclosures come in assessing the Central Intelligence Agency's involvement with Nazi emigres. Scholars and previous government reports had acknowledged the C.I.A.'s use of Nazis for postwar intelligence purposes. But this report goes further in documenting the level of American complicity and deception in such operations. The Justice Department has resisted making the report public since 2006. Under the threat of a lawsuit, it turned over a heavily redacted version last month to a private research group, the National Security Archive, but even then many ... portions were omitted. A complete version was obtained by The New York Times.