I subscribe to a watchdog website that monitors and posts videos of police brutality (the liberty cryer) and there are enough to raise an alarm in some places. I don't see so much a  systemic problem as I do a localized one. And the biggest problem is not the shooting but the police force coverup of them. Another big problem is always going strait to race as the cause. If there is a problem and you root out the wrong cause you fail to fix the problem and may well exacerbate it. 

Nation wide police fatal shooting consist of 50% white, 25% black and 25% others. The only ones we ever hear about nationally are the blacks.  Why is that?

Another problem is that police almost always are justified  when they shoot someone, even in that case in Chicago where the cop shot a man over a dozen times while he lay on the ground.

If BLM wanted to work the issue instead of making a racial statement the would include the other 75% of the nation that are included in the shootings.