outside of it being a) an accidental discharge which would be a horrible tragedy, but at least somewhat understandable (although not excusable), or b) a homicide

I don't see how the officer could claim he used his weapon in self defense. If two trained police officers can't subdue a 40 year old woman in her pajamas without resorting to deadly force, god help us all. Although I suppose they could/would argue they thought her cell phone was a weapon.