This police killing also looks like a wrong 'un, like the "I can't breathe" one in NY.
http://www.huffingtonpost.com/2015/06/08/michael-slager-indicted_n_7535520.html
There's a very difficult area of police weapon use in which it is easy and possibly correct for an officer to justify him/herself on grounds of self-defence.
This one wasn't one of those.