OK, You pulled the trigger, the deer is down. The game isn't over. Now is the time for discipline and prudence. You should have jacked another shell in immediately after pulling the trigger and secured the gun on safe. If bowhunting, you should be waiting anyway. When you find your deer, walk slowly to it. Approach from the rear. Stand near the deer for a few moments and just watch it. If it is still alive, and you pay attention, you will see some movement in the chest at some point. If after a couple of minutes you see NO movement, move around to the head and touch it's eye with a stick. If you can indent the eye and no blinking occurs, it is dead. One reliable indication of deadness is if the eye is open and no blinking occurs for several minutes. If the eye is closed, watch your a$$. Deer seldom close their eyes completely when dead.