Again, like most have said it can be a very sticky issue. I would talk with the said person and discuss the issue, trying to understand why they would do this act. I know, I would no longer concider that person a hunting partner nor would I want them hunting on the same property as I. As for turning them in, again it can be very touchy but I beleive I would. They need to understand their actions are breaking the law and it really puts a bad light on the hunting community. I know in my neck of the woods it's getting harder and harder to find willing land owners to let you hunt on their property.