[MereInterest]

> you will never in a million years convict someone of murder when they were returning fire

Sure you would, if somebody was returning fire after having been the initial aggressor. Suppose I were to break down your door. In many states, you would be justified in defending yourself (Castle doctrine). If I return fire and kill you, I would be guilty of murder. You had a right to defend yourself, and I did not have a right to return fire.

That's the a huge point of the outrage, that whether or not the police announced themselves is in question, and witness reports vary. If the police didn't announce themselves, then there is no way for somebody in the house to determine whether it is a valid warrant being served or a violent home invasion. (Or both.)