We have bombs (non-nuclear) that can wipe out 600 yards in any direction. A few of those, well placed, and that will be the end of that.
OR, just leave him in his cave and let him slowly starve to death while we watch. I kind of like that plan better. A little suffering with our justice would make me much happier.
Wait, how about we find a few hundred sewer rats, cover them with anthrax and let them loose in the cave. Eventually nature will take it's course.
We could let him nearly die, nurse him to health, just so we can kill him later. That works too.
I want him to suffer like a dog... Is that to much to ask?