Unfortunatley thats how hunting goes sometimes. I wonder if something didn't chase that deer or spoke it bad after you left it the first time. The same scenario happened with my dad and abear one time. He had gut shot it that night so we waited till morning before tracking it. While tracking it we came upon a bunch of ruffed up dirt and grass.After looking closely to the ruffed up dirt and moss we found Timberwolf tracks and dung. We never found that bear, i'm sure the wolves chased him for a long ways before they got him. Sounds like you did everything right, there's nothing a guy can do sometimes. Mother Nature does what it wants at times.