X2 on the shotgun advice, and the dogs. I can't add too much more other than my condolences. Good luck ! I hope that this will end quickly and well for you.
I most definitely can relate to to feeling of having your property violated.....and worse, in this case.
It's not easy to get over.
Perhaps you might consider getting an automatic game camera or two. Turn the flash off for daytime use. It's a cheap way to keep track of who comes on your property. I know several people that use them for this purpose.
Maybe around a hundred bucks for a digital, depending on the camera. G/L
