For John, BLUF: Mistakes happen, even with the Police. Nothing to see here; just move along.
Sometimes even the Progressive Press gets it, as with this article by Ms Candice Bernd, in Truthout, "Wisconsin Passes First State Law Requiring Independent Investigations of Police-Custody Deaths". As you read you will note that the person pushing this rock up hill was a former Air Force pilot, who understood the importance of independent mishap investigations to find out what went wrong, so corrective actions could be taken for the future. In my mind, this is not about punishment, but about the search for the truth.
In case you don't fancy Truthout as a news source, here is an article by Ms Gina Barton of the Milwaukee Journal Sentinel. "Gov. Scott Walker signs police custody deaths bill".
And, this took place a little year ago, in early 2014.
Regards — Cliff