I've had similar situations happen to me, but worse......it was a brother-in-law.
You have only one choice......let him know you are very serious! Therefore, he will no longer have the priveledge of hunting on your property.
I have several rules on my property:
1.) (Most important) No one can hunt unless they do their part and helping me maintain the property by helping me in the off season. Mowing, cutting trees, planting food plots, maintaining feeders and stands, purchasing tree stands, etc. etc. Some people just don't realize just how expensive deer hunting can be when doing all of the above things, not including price of the property.
2.) They have to harvest a doe before they can even think about harvesting a buck. Sometimes.....it's two does. What I can't believe is that some people think that does are the easiest deer to shoot with a bow. I don't get it.......I've harvested 6 deer this year with my bow, only one being a mature 140" 11 point. He was the easiest of all of them. Come to my hunting woods and try getting the string back on a mature doe. Those that do.....appreciate the almighty "mature" doe much more once they do!!
3.) 8 Point or better! No exceptions! If they happen to mess up and shoot a seven or less......then their done! A bowhunter must have the patience and wisdom to KNOW without dought what they are shooting. If they don't, they don't shoot.
Once you enforce rules such as these, it makes the hunting better for everyone in many ways......most of all, it makes everyone better hunters and if they have a brain they will thank you for it, eventually!! Hopefully.