Are you serious?
It's not murder to keep your property from being stolen.
Actually, it may be murder, especially if you planned it in advance. Laws regarding the use of lethal force by civilians typically reserve that right to instances where a person's life is in danger. Merely defending objects does not generally permit the use of lethal force. To distinguish the difference between property that are belongings, and property that is your house and land, many states have a make my day law that allows a person to use lethal force against an intruder in their house (or occasionally even merely standing on their land) if there is even a hint of possibility that the land/home owner's life or the life of someone legitimately on that land or in the house is in jeopardy. But those laws are specific in intent, and do not justify shooting someone who is simply carting off your belongings.
Some law enforcement officers are permitted to shoot fleeing felons (they used to be obligated to shoot fleeing felons, but that requirement has not been enforced for some time to my knowlege) even if the fleeing felon is doing nothing but, well, fleeing. But even cops fully authorized to shoot people now hesitate to shoot anyone who is not a direct and immediate threat to someone. It's just not worth the hassle.