Who knows if those facts are accurate, but if they are it is absurd to suggest that the cop "executed" the kid, as several have suggested in this thread.
Is he dead? Did he receive a fair trial? Are there no options in between "halt" and shoot to kill?
Look, no one knows the facts yet, but IF the facts are once-mugged police officer with fractured face, assailant who tried to take his gun previously now charging form 30-40 feet . . . . there are probably NO options other than SHOOT and you do not shoot a gun other than to kill, so "shoot to kill" means little as a distinction.
But, let me ask it, do you hold the assailant accountable in any way for his "execution"?