It's not clear that the robber was leaving at the time he was shot. The robber was still threatening people with the gun when he was shot. Shooting the robber i

It's not clear that the robber was leaving at the time he was shot. The robber was still threatening people with the gun when he was shot. Shooting the robber in the back was a way to get the jump on him—drawing on someone who has already drawn on you is generally suicide. As for the risk that someone else might mistake the shooter for the robber, anyone who has taken a concealed carry class has learned that there are risks to defending yourself. It's a choice you make because you don't think there are better ones. But fundamentally, I'm objecting to your characterization that this guy was looking to legally kill someone or that it was motivated out of a desire to keep his wallet. The robber was threatening people's lives. The danger was not over. Shooting the robber was a reasonable choice given what the shooter knew at the time.