That actually falls under my next question, which I realize is subjective, so I don't expect anything other than a subjective answer.
You talked about the police saying “Well, I don't need you as a witness”, which can be construed by some as neglecting that person's safety. But I would suspect there are many criminals who may want protection simply to save their sorry butts because they've fallen out of favour with their own chain of command. Is that the source of some cases that might be construed as neglected?