Some of those great cops DO try to do the right thing.
You know what happens to those cops? They end up losing jobs or mysteriously transferred. In other word retaliation. Except it's hard to prove it when it appears to be a natural occurrence.
The good cop did what they were suppose to do report it. However what happens after that varies.
This is tends to happen. The wrong doer (more than the person reporting the issue) transfers or leaves. Where investigations do not continue in the new location.
It's how a lot of toxic school employees escape. Resign and leave before anything else flares up.