Besides, police murders don't tell the whole story. How many times a day are people having their constitutional rights violated by police officers? How many off-the-books torture chambers exist that haven't been revealed? Can anyone actually say with a straight face that these tactics aren't commonplace in just about every major city in North America?
The Toronto Police Department, for instance, illegally detained almost a thousand people during a G20 protest. They did so by simply lying to the public prior to the event, arresting people, than letting them go without charge.
The problem is both cultural and structural. We need clear laws governing the use of state violence. We also need to abandon the tough on crime mindset entirely, and that means teaching the John Galt's of the world that, no, killing people isn't justice, harsh prison sentences don't work, criminals are not necessarily bad people, etc.