Well there's your problem. Having the investigators of misconduct report to the police chief?

Whenever the cops murder someone in the street, the police chief is the guy that immediately runs out to deny everything, claim everyone acted in accordance with department policy, and claim there was no video despite existing legislation requiring body cams and multiple bystanders on scene with cell phones out.

Going to go out on a limb here, but maybe the guy in a position everyone immediately assumes is spearheading the cover-up because of how often exactly that has happened shouldn't be the one that gets to review whether or not misconduct happened.