Why didn't you keep tracking when you went back out there? 2.5 hours is not that much time really.
I have been hunting every morning before school for the past week now in search of a big buck.
I shot him at 7 am and decided to come back at 5 pm.
It probbly got dark on him.
I will say a prayer for you to find your buck.
I hope the coyotes didn't get to him.
Good Luck.