@edgarblythe,
In Max Hasting’s book about WW2 he talks about the police groups in Eastern Europe at the beginning of the Russian invasion.
One police chief told his group they had a rather unpleasant task and they could opt out if they wanted.
Basically they had to clear all of the Jewish people out of a certain neighbourhood and kill them. Nobody was forced to do anything, everybody who took part volunteered. About 30-40% refused to take part, of those who did about half had to stop after killing one or two people, but the rest had no problem killing dozens or more.
Now volunteer police forces in occupied Nazi Europe are a far cry from those of a democracy, but the point remains, they didn’t take much persuasion to start committing atrocities.