Qualified Immunity is a red herring. Don't get me wrong, it's a whole cloth creation of the Supreme Court that flies in the face of section 1983 and Congress should have fixed this problem decades ago, but QI is, first of all, limited to civil rather than criminal liability and, secondly, every police force in the country indemnifies its officers in the event of civil litigation that arises out of their actions.
If you want a real fix here, it's holding police accountable. Not throwing up hands and crying that "the big bad police union said that if we arrest officers for murder they'll go on strike, so what can we do?" Not only should their jobs not be protected when they commit obvious wrongdoing, they should be held to a higher standard in terms of criminal liability than Joe Citizen is in general. (Conversely, bona fide good faith error should be treated as just that).