I feel sympathy for a Nazi concentration camp guard too. People do evil things, both by choice and due to circumstance. Usually a combination of both.

can find a job anywhere

Yes, as a police officer. All police departments are complicit in evil, and most of them would fire (and refuse to hire) a cop who reported something like this, especially if she were a "hero to the public". Police departments do not want heroes. They want people who do as they're told and don't push back.

I, at least, can begin to imagine a society where cops are regarded as our saviors and protectors

I can't. That's not, and never has been, the purpose of a cop. A cop enforces the law as it exists - messy, designed to benefit those in power, often contradictory, and definitely distinct from both morality and ethics. In general, having people to enforce the law is much better than not having people to enforce the law. But they're not superheroes. They're ordinary people, selected and trained and pressured to behave in often evil ways for the stability of the nation-state.

If there's just one cop who's doing really evil things, it's useful to talk about personal character. If it's endemic to the profession (as it clearly is), then let's analyze the situation materially and make changes to prevent rewarding or encouraging that behavior rather than focusing on the particular characteristics of any given person enmeshed in it. The latter leads only to reaction and demands for punishment ad infinitum, and can exacerbate rather than solve the problem.