I live in the area and this has been all over the news. It sounds like he was a normal guy who got carried away with anger. He said over the last couple years there have been 8 break ins at his house, and just last month he had ~$10000 worth of guns and cash stolen.
The only thing I think he was really in the wrong about was waiting a day to call the police. He claimed that he didn't want to bother them on Thanksgiving, but that is an awful excuse.
Anyway, I don't think he has a criminal history, and his neighbor even went to the press to defend him. The guy just wanted to be left alone. I don't think the burglars deserved to be killed, but when someone breaks into your house to steal things how do you know what they're going to do?
I have no sympathy for the burglars, but I do feel bad for the families.