I sort of answered this in my comments on this killing in the earlier posting.

 I also think many people would be surprised how when it comes to misconduct and mistreatment of people that these offenders are equal-opportunity abusers.  What I mean is, many don't give a crap what demographic group the people may be of (oddly, I used to hear rumors that particular Black officers in our department treated fellow Blacks worse than other races).

And really, in many of these cases, it is about power - just like sexual assault is not about sex but power, physical abuse by many of these is the same thing - subjecting one considered lesser to the abuser and with little fear of reprisals because he or she can (yes, I am aware of female officers familiar with the use of a heavy hand; not as often, but they do exist).

Here is an illustration of how so much of this involves the perception of power - over the last decade or so there has been a growing refrain of those in policing to imagine themselves recorded 24/7 - that everyone has a camera nowadays and an officer is always being filmed somehow and everywhere.

So, with that mental construct (that obviously is not setting in), these things are still happening - so how is it that when officers are constantly bombarded with reminders of always being recorded these things happen?  It is because of their perception of their power and what comes with it.

Now, don't get me wrong - I'm not suggesting officers become better at misconduct off-camera, but that they need to realize that in today's America cameras are everywhere and everyone has them (my point is this mindset needs to be completely drilled into one as a mean of misconduct deterrence and not with the intent of learning to better hide one's acts of misconduct).

Lastly, when it comes to American government, almost everything is done on the cheap, so the hiring practices are all over the place and mostly installed to process large numbers of applicants in the easiest and cheapest way possible.  And this goes back to my point about hiring and selection - a better way must be developed but finding such a way is both simple and hard.