I think you are clueless. I think you have issues. I think I am wasting my time even attempting to converse with you on an adult level. That's pretty much what I think 
It's not that you are wasting your time, it's that you are trying to explain something that cannot be explained.
It's not your fault either.
I'm against capital punishment altogether. That you actually shoot someone in the back is inexcusable in my world. And trying to explain the circumstances surrounding the cops decisions is inconsequential because the act of killing someone you are sworn to serve and protect prevents you from doing such a thing.
What is it YOU do not understand? Why must a civilian point THIS out to you?