These trials heightened general public and international understanding of the extent of the crimes that had been perpetrated in occupied Poland some twenty years earlier by Nazi bureaucrats and persons acting as their executioners.

In these and subsequent years, separate trials prosecuted personnel of the Belzec (1963–65), Treblinka (1964–65), and Majdanek (1975–81) extermination camps, all of which had been located in Poland.

[3][4] Zeug asked authorities for help, and by spring 1960 had identified three dozen men directly involved in Action T4 (the killing of mentally and physically disabled persons in Germany) and in Operation Reinhard.

On 23 June 1960 he filed his first letter of recommendations for prosecution at the Central Office of the State Justice Administrations,[5] requiring judicial action against 19 suspects.

[9] The German court in Hagen initiated proceedings on 6 September 1965 against twelve former members of the SS camp personnel, accusing them of crimes against humanity.

[2] In the 1965–66 trial, the defendants claimed that once assigned to serve at a death camp, they did not believe they could refuse their orders, citing the statement made by Christian Wirth to the personnel at Sobibor (quote): "If you do not like it here, you can leave, but under the earth, not over it."

But the prosecution noted that SS-Untersturmführer Johann Klier, who asked to be transferred from Sobibór on moral grounds, was not punished but allowed to leave, which proved that the contrary was true.

[4] By the time of this trial, some of the public had learned about SS-Oberscharführer Erich Bauer, an officer who was known as the gas chamber "meister" and was described by survivors as notoriously cruel and violent in his treatment of prisoners.