Let's not confuse the members of the Gestapo that murdered the escapees after they were recaptured with regular Germans.
What type of character volunteers to be a secret policeman for a brutal and repressive regime? I strongly suspect that the occurrence of such psychopaths is relatively uniform amongst nations, but that most just don't get the chance to play out their potential roles in most places.
I also doubt that such illegal acts against high-profile prisoners would be carried out by foreign help.
After a quick search, the trials that lead to the execution of 13 of the 18 accused in 1947, and the imprisonment of the other 5, seemed to be directed against men with traditional German names.
Stalag Luft III murders - Wikipedia, the free encyclopedia