This one is tough..
He has been burglarized 5 or 6 times as reported by friends and neighbors..
he lives alone, hears someone breaking in while he is in the basement. he has no idea if they are kids or not.
As he sits downstairs he sees one of the people coming down the stairs and shoots him..
Then, hearing the gun shots, the girl decides to come downstairs.. WTF
So if you are the guy and you just shot one person and yet the other person starts to come down, you have no idea if they have a weapon drawn or not so you shoot first, ask questions later.
But then he does go
WAY overboard by executing the girl and admits it..
He had every right to take the first shots at them .. he had no idea they were "just kids" ( hard to say that since the were 18 & 17) and for all he knew his life was in danger.
Guessing this will get plead down to Manslaughter for the boy..
The girl is the one that is the most disturbing based on his own descriptions of how he "took the kill shot" and for that one I could see the 2nd degree murder sticking.