Outstanding advice above!^^^^^
You have nothing to gain by going in tonight. It sounds as if he is dead, but why risk it?
My guess is that if he was only 30 yds. from the hit, 30 min. after, he had bedded and stood up when you saw him. Since you made the rt. choice and backed out, he most likely bedded again.
If he is gut shot, he may take as long as 12 hrs. to die. But he will bed down and become too stiff to jump/run if you leave him until morning.
As was said above, I would enlist 1 or 2 experienced helpers. You take the lead with your gun at the ready. Let them spot and mark blood while using soft voices and hand signals. Be ready to finish your deer if need be, but I'm guessing you won't need to.