Chris:
One could write an extensive law review article on the subject you mention. The statutes and cases vary from state to state. Some states are more permissive than others when it comes to a homeowner's right to use deadly force against an intruder. Even in most of the more permissive states, however, the law will require that the homeowner come forward with evidence that deadly force was required. After all, while the intruder might be a stone-cold serial killer, he or she might also be some unarmed and confused teenager looking for something to fence in order to feed a habit. And there is always the problem of some ambitious prosecutor who aspires to higher office. Each case will turn on its own facts and the law of the particular jurisdiction.
All of this is deadly serious stuff. However, as the maxim goes, "I'd rather be tried by 12 than be carried by 6."
Stay safe.
RS