The Stasi is known as having been one of the most effective and repressive intelligence agencies. However it was founded only five years after the fall of the Nazi regime and disillusion of the Gestapo.
How was it possible that the Stasi was so effective and seemingly staffed by those so dedicated to its aims, when only years before a different organisation had stood in its place, also highly effective and staffed by people seemingly dedicated instead to Nazi aims?
Presumably no Gestapo employees went on to join the Stasi? Due to the opposing political ideologies, and post Nazi purges? But then who were these capable new Stasi recruits? Where did their expertise come from? And what of their ideology? Were they ex-Nazis who’d had a drastic conversion? Or newly liberated closet-communists?
The leadership positions of the first generation of the Stasi mainly consisted of the old KPD members and Red Front-Fighters of the Weimar era, many of them were also veterans of the Spanish Civil War. However, the mass of recruits for the Ministry for State Security was largely taken from the youth. By 1952, about half of the Stasi staff were under their thirty. Youth recruitment was part of the Stasi’s intentional strategy to avoid recruiting moles. They were afraid that former NSDAP members would work in an alliance with Western intelligence agencies.
The Stasi sometimes used former Nazis as “unofficial informers” (Inoffizielle Mitarbeiter), keeping them out of the public limelight, in what has been called a “secret politics of the past.” They argue that many former Nazis in the West were working for what they saw as enemy circles, and that it was important for the GDR to have access to these groups. Examples of former Stasi informers who were ultimately brought to trial include Johannes Kinder; Franz Timm, alias Neumann; Georg Frentzle; and Karl Gorny. In the cases of others, such as Josef Settnik, who formerly worked in the Auschwitz political department, or Karl Mally, who had worked for the Gestapo, they claim there was simply not enough evidence to bring a compelling prosecution.
Source: Gieseke, Jens. The History of the Stasi: East Germany's Secret Police, 1945-1990, 2015.