It's not murder. It's still self defense. I don't buy that someone who is attacked has to understand that at some point them defending themselves stops being self defense and is suddenly, magically and inexplicably, murder.
Someone threatens you and gets killed, too bad for them. Nobody should have to go to jail for that.
Once the immediate threat ends it is no longer self defense. Nothing magical about it.
I had two kids (about 19yrs old) grab two rifles off my rack and run out with them. I went to draw my gun. But I could not. They were no threat to me, making off with property.
Now, if he had reached even for his cell phone I would have greased him right there, believing myself under threat. BUt as it was, I was not entitled to shoot him.