Most people (including my wife) seem to think that Rick clearly shot Dr. Pete, but that the producers just chose not to show it directly because it was perhaps just a bit too graphic. I say "Bull Gronky!" On this show, there is nothing that they love better than to graphically "show it". Can you remember poor little Beth Greene? I don't know who or what it was that Rick did indeed shoot, but I very much doubt that Dr. Pete would have been shot in the head or elsewhere without us being shown every minute detail. How about Glenn on this same episode, who clearly must have died when multiple walkers fell upon him? We didn't see him torn apart, so that means that he must have survived the scene. On this show, if you are not shown indisputable, unsurvivable carnage... then there is a reason for it.