A grand jury? Certainly with forensics they can determine how many shots were fired by the perp and where they landed, and they have the witness testimony. I would think that would be enough to decide.
hope it works out for him. in 3 out of the 4 different “personnel defense” courses I have completed, discussions of costs defending yourself in a what eventually turns out to be a correct use of deadly force scenario was shown as just hard to believe.