Absolute Shit Show: Informers, tattle-tales, narcs, and busybodys (ordinary citizens) during WWII

Many focus on The Nuremberg Trials but what of the ordinary citizen who turned in someone for simply not liking them or in a poer play? Ordinary citizens who tattked on their neighbors (mostly innocent people) and by extension, sent them to their deaths via Concentration/Death Camps.

nullum crimen sine lege -- "Crime without law" (crimes commited for which there is no law against it)