Historian Henry Leide drew on Stasi files that have not been opened to the general public since the fall of communism in 1989 to trace the often well-paid careers of 35 of Hitler's men who found a reprieve in the secret police.
The case of SS officer Hans Sommer is not exceptional, according to the book titled "Nazi Criminals and the Secret Service: The German Democratic Republic's Secret Ways of Dealing With the Past."
Sommer was instrumental in the bombing of seven synagogues in Paris in October 1941. But after World War II, he spent years spying on right-wing politicians for the new regime in East Germany, and was later posted to Italy where he continued to do the same.
Officially, the German Democratic Republic (GDR) adopted a resolutely anti-fascist stance and in the years following World War II its courts condemned more than 8,000 former Nazis.
The Waldheim trial in Saxony in 1950, for example, saw 32 former Nazi operatives sentenced to death.
Nazis blackmailed into working for communists
But the book claims that high-profile convictions covered up a more cynical reality -- instead of serving sentences they were blackmailed into working for the ubiquitous Stasi, which had more operatives per member of the population than any other spy network in the communist bloc.
"The Stasi deliberately and systematically recruited Nazi criminals, sometimes those who orchestrated massacres, as informers and agents both in the east and the west," Leide said.
Josef Settnik, a Gestapo operative who was based at the infamous Auschwitz death camp, was awaiting a death sentence and had already said goodbye to his wife when he was recruited by the Stasi in 1964 as a church spy.
Another case in point is Willy Läritz who was a member of the Gestapo in the eastern city of Leipzig who took his spying skills over to the Stasi and gained a reputation for "heavy-handed" interrogation methods.
He was drafted into the secret police in 1961 "to support our fight for peace and socialism," according to an entry in his Stasi file.
Läritz was considered vital because he had compromising information about other Nazi operatives who were then blackmailed into joining the Stasi as well, Leide said.
Stasi recruitment a "second chance"
The former Nazis were told that they would be given a second chance in return for cooperating with the communist regime, which had quickly realized that in some areas they had skills that were hard to find elsewhere.
"The presence of some former National Socialists in the new state party, the Socialist Unity Party of Germany (SED), was really just the tip of the iceberg," Leide writes. "Where qualifications were needed and there was strong competition from the West, they could be found in high concentrations."
If the former Nazis showed that they had "adapted" and were loyal to the SED, they could moreover count on senior posts.
Secret police helped protect Nazis from prosecution
Leide, who is part of the committee that manages the Stasi archives today and enjoyed special access to its files, said that the secret police not only used the Nazis but also protected them from further prosecution, partly in a bid to preserve the image of the regime.
This was the case with Harald Heyns, who was convicted of war crimes in France and Britain but managed to hide in the GDR under a false name.
The authorities deliberately turned a blind eye for fear that if the truth were known, it could "harm the image of the GDR."
While the book reveals that large numbers of Nazis spied for the Stasi, their presence in other sectors of the communist has been well-documented.
"Even at the time we knew that people with a Nazi past were being drafted into the Volksarmee," the "people's army" of the GDR, said Richard Schröder, a philosophy professor at Berlin's Humboldt University.