I bet it’s dead within 100 yards or so. As stated earlier, no pass through and the entrance probably left one or two small drops. I’ve killed a couple this year that I could not find blood because I was looking in the wrong spot. I started making circles and walked up on both. At 225 yards and dark, it would be very easy not to find any sign - especially with a .243 and no exit. Good luck and show us a nice buck.