This was shown by the sorry saga of the OSI's attempt to prove that a car factory worker originally from Ukraine, John Demianiuk, was "Ivan the Terrible", a particularly brutal guard at the Treblinka extermination camp. Based on testimony from a number of survivors, Demianiuk was deported in 1986 and sent to stand trial in Israel; the case collapsed. It was not until 2011 that Demianiuk was finally convicted in Germany as a guard, not at Treblinka but at Sobibor. By then he was over 90 years old; he died the following year.

The desire to obtain victories in court sometimes created perverse incentives. The OSI could find itself concentrating on bringing charges against relatively minor figures because there was documentary evidence. As if these barriers were not enough, it could find itself facing pressure to abandon its inquiries from politically influential ethnic lobbies or prominent figures such as Pat Buchanan.

Created in 1979, the OSI operated within the US Department of Justice until 2010 when it was merged into a Human Rights and Special Prosecutions Section. The Nazis Next Door gives a vivid picture of the frustrations and victories of successive heads of the OSI, especially Neal Sher and Eli Rosenbaum.

Lichtblau took leave from the New York Times in 2013 to take a fellowship at the US Holocaust Memorial Museum in Washington to review the documentary evidence and to conduct extensive interviews.

Rosenbaum is probably the most important and most successful of all Nazi-hunters but is far less known than Simon Wiesenthal and others who have enjoyed the limelight. After stellar academic performances at the University of Pennsylvania and Harvard, he has spent nearly all of his 35-year working life in the OSI and its successor body.

Rather than give a comprehensive list of inquiries, prosecutions and other actions, Lichtblau provides the inside story of a number of key cases, most of them sensational at the time but subsequently almost forgotten.

An exceptionally well-known example, whose background the book describes, is the exposure of former UN Secretary General Kurt Waldheim and his resulting ban on entry to the US.

Two other riveting accounts typify the book. One concerns the investigation which led in 1983 to a plea bargain with Arthur Rudolph, Wernher von Braun's former deputy in the production of the V2 missile. In lieu of prosecution for his role in the administration of slave labour in the underground missile factory at Dora-Mittelbau, Rudolph agreed to give up his US citizenship and return to Germany.

As a third-year law student at Harvard, Rosenbaum had chanced to see a photograph in a local bookshop. Supplied by von Braun for an admiring book about US rocketry, it showed Russian prisoners of war "contributing to the manufacture" of Nazi rockets. A passage in the book, The Rocket Team, recounted how Rudolph, as operations chief at Dora, had been obliged to leave a New Year's Eve party to sort out an unexpected engineering glitch. On the basis of this account, Rosenbaum was able to obtain an admission from Rudolph of his participation in the use of slave labour at Dora-Mittelbau.

The second account relates the long search for evidence sufficient to strip Alexandras Lileikis of his US citizenship in 1996. A former security police chief in Vilnius during the Holocaust, Lileikis returned to face trial in his native Lithuania. He died four years later after his trial was adjourned on health grounds.