How a French computing expert sabotaged the Nazis
weeklygazette.substack.com
weeklygazette.substack.com
While I know nothing about the work of René Carmille, from what I was told it's that in most cases it was neighbors who denounced Jews, and you could be denounced even if you were not a Jew, but have some disagreement with someone.
Equally in the same proportion, and sometimes by the same people, Jews and more largely all opponents to Nazis, including English or US plane aviators, were hidden by people (one of my grandmothers did it for Jews).
It was a complicated time, with no clear delineation between "good" and "bad" people.
People did what they had to do to survive. It's easy to tell them they were wrong in hindsight.
Just to add so this comment can't be misconstrued later: The nazi party was evil. Committing genocide is bad.