What matters is the circumstances of the shooting and the fact that the local police ignored an obvious murder. The race of the individuals involved are critical because of it being in the south. Were it anywhere else, and the people involved of the same or differant races, and the local police reacted in this manner, it would warrant federal investigation, also.
The asshole was out to kill somebody. Had a concealed carry permit, and was packing heat. When you are in that positon, and you initiate the conflict, you are automatically wrong. When you have just been told to back off, as was the case here, you have committed murder.