From the Holocaust Encylopedia: The police in the Weimar Republic
In the years of the Weimar Republic, most active policemen were not Nazis, meaning they were not members of the Nazi Party or of Nazi organizations.
It also says at the top of the page,
Most German policemen were not members of the Nazi Party prior to 1933.
I've never seen these claim before. Is there any information on the actual composition of the police, and how many of them were members of the "Nazi Party and Nazi organizations"? It presents this as fact, however I am skeptical.