Seems to me if he was shot in the back, inside the home, it is self defense. I think the Zimmerman defense applies here.
it really depends on the circumstance. If the “bad guy” in this case is peaking around the corner pointing a gun in the direction he thinks you are, and you come up behind him from a different direction and shoot him, then its self defense. He’s in your home, he’s trying to get you in his sights, and has no intention of running. You are defending your property and your rights and killing the invader is justified. And really, it just comes down to the castle doctrine. Are you in your home? Is the person invading your home? Legitimate target. Period.
that said, someone breaking into a drug dealers house isn’t really surprising. Not sure why they are wasting any time with this case at all, except maybe to grandstand and try to make themselves more electable. So then you have three immoral people involved- dealer, invader, and prosecutor.