It is relevant.
If you severely wound an intruder, but he is armed, you are likely justified in shooting him again because you fear that he is still able to use his weapon even if he is injured.
But if someone is lying on your floor, unarmed and gutshot, then we're not dealing with self-defense anymore.
You obviously didn’t read all of what I wrote.
Unarmed is NOT relevant regarding shooting an intruder. Killing an incapacitated intruder IS relevant. Which is what I said originally.
Unarmed, teenage, girl - are all irrelevant facts - unarmed, teenager, girl or not, she was invading his home and therefor legally subject to lethal force.
Once she was incapacitated - whether initially armed or not - further deadly action is uncalled for and indefensible. Incapacitated is the relevant fact. He shot to death an incapacitated, criminal intruder.