Well you’re right, BUT...
If in the most extreme emergency, NEVER tell someone you were trying to KILL a perp, or drain their brain of blood, but rather STOP them.
“Officer Friendly, I was in fear for my life! I told him to stop! I said it repeatedly! But he kept coming!!! I just wanted to stop him. I was sure he was going to kill me if he didn’t stop.”
This need to stop those rabid savages are the reason you hear about the cops putting a dozen rounds in them. They want to stop the brain from functioning by cutting off the blood supply. It is the simple application of human physiology.