I’m pretty certain he went on to become a staunch supporter of Hitler
The exact opposite is true.
I must have been remembering that his research between the World Wars lead to the development of Zyklon B muddled that up with some other chemist (maybe Otto Ambros?). I’ll see if I can find my source.
Edit: probably Richard Kuhn who fell into line and fired Jewish coworkers at the direction of the Nazis or Herman Kolbe who was an outspoken German nationalist and anti-Semite. I use all three of them as examples of prominent scientists behaving badly in my O-Chem course.
Zyklon B was not developed for killing people. The most common usage was for killing lice in clothes. (To make it very clear: It was also used for killing people in Vernichtungslagern).