If they have to be weighted against each other, I would rather see some guilty go free than to overlook police misconduct. Sometimes you just don't know if an individual is guilty. At any rate, we have a press and the internet that can argue this at will.
A false dichotomy. If a policeman exhibits misconduct, then he has committed a crime and needs to go in the dock along with the criminal.
I do NOT AGREE with releasing a criminal SOLELY because of police misconduct. That is unduly punishing society, which is innocent of any wrongdoing in the matter.