Unless you put up a huge fence it will not effect the deer any. They hop over them like they are nothing. Then again it may not keep the hunters out either
. But it will define the boundries better and make it easier to prove they were on your land.
Fences are kind of pricey though.
I know what I would have done had someone pointed a gun at my 12 year old kid or grandkid. But I will not suggest it on the internet. All I will say is bullets and shovels are cheap, if you have a back hoe it's even better.
Your best bet is to talk to the local DNR or local police and see what advice they can give you.
Paul