Just because there was a drop of blood in the road does not mean he crossed. He may have back-tracked before crossing, or crossed back after crossing the road. Be persistent. I know the feeling you get when it starts to look like a deer is lost, but I've learned that it just takes more effort sometimes. Once all tracking is exhausted, work out a logical plan. I first check all logical places, like water, thickets, etc. Then I go to a grid approach. If it takes all day, that's just what it takes. A few friends are a great benefit if you can get them to help.