I've always found the "either or" argument odd. Why must it be either the police, or the crooks, must be allowed to hurt innocent people? Is there no other choice?
As I've said before, being a police officer is not an easy job, and many people are not suited for it. Being a nurse is not an easy job either that anyone could perform. And in both cases your job, as defined by society, is to help other people.
This does not give you a right to decide on your own if someone you consider an "evil doer" should be punished. If you are a police officer, your job is to protect other people from the "evil doers" and to arrest them if you can do so without hurting anyone else. Other people decide if they are guilty and how they should be punished. If you are a nurse, your job is to help the "evil doer's" medical condition as much as you can. You cannot decide to punish them by unnecessary, painful procedures or kill them with a lethal poison.
If, as appears here, members of the police and city politicians were racist in their actions, thus harming a subset of society unfairly, and the police were used to collect money rather than protect people, then they were not doing their job. In fact, these aspects have nothing to do with the real jobs assigned by society to police: helping and protecting people.