The idiots did try to rob a store with guns endangering the lives of everyone involved, I wonder if they thought to themselves that they might get their heads blown off. I would say it's manslaughter due to mental duress or even plain self-defense. People can still survive gunshot wounds to the head & it is entirely plausible that the guy was going back to get more ammo for protection when he saw the attacker still moving on the ground. Why didn't he take the gun off the guy? Perhaps the gun disappeared underneath the suspect or flew away somewhere hidden, or he just wasn't thinking clearly. Even if he did kill the guy out of anger & spite, while I'd like to think I'd act differently, one could never be sure how they might act when put in a circumstance like this.
Clearly, the extra 5 shots wern't necessary. He left to chase the other suspect, came back in all casual walking into the back room and paced on out. I don't think it was necessary. I also don't agree with the verdict. But. What pisses me off is the boys family. I understand your son got killed, but he walked in to a store, gun in hand, trying to rob it. I know if that boy was me, my parents would be sad at my passing, but would not show such remorse over attempted robbery and attempted murder. The kid got what he was asking for.