Self defense is what you do to save you or others. Killing because you are mad, or to enforce your non-bible supported worldview, of death for a theft is simply murder. Life is better when you can avoid murder.
No, seriously.
It’s a challenge to train Marines and cops to the point that they will enter a room where rifle fire is happening. And we are to believe this 18 year old girl just does it without even calling out for the guy who just went in ahead of her? And then she laughs when hit in the gut or lower with a 223 from a few feet away.
Sure,,, it happened just like that.
This sort of thing happens in manga ~ so the cops would be well advised to see what he’s been reading. might give them a clue about what was going on before he shot them.
Perhaps she waited outside while he went into the house. Smith shoots the guy, puts the body in a tarp and drags it away. Then, not having heard the gunfire, and wondering where her cousin is, she goes in looking for him. They must have believed Smith was away for the holiday or something, and they would have the run of the place.
I wonder, if you were hiding outside the house, if gunfire in the basement would have been audible. According to Zillow, it's a 5082 square foot house. It defies belief that she would have gone into the basement knowing there was a guy with a gun inside.
On the other hand, maybe he got the drop on them, marched them down to the basement, and executed them. And then fed the cops a cockamamie story.
In either scenario, it also defies belief that the guy would turn himself in instead of simply letting the pair disappear, having disposed of their remains and taking his chances they didn't tell anybody their plan. He is apparently retired State Department security, so he obviously knows self-defense law.
Sort of a side note, but if one is concerned with “immediately stopping the threat”, a .223 is probably not the most effective round.