Deancutler, do I read your post correctly to understand that you live at your pond?
If so, that's brazen on the d-bag's part.
I've found that leaving written messages for trespassers can be helpful. Also leaving visual cues like used paper targets, or a 5-gallon bucket riddled with bullet holes right by where the trespassers hang out are effective deterrents.
So, nothing showed on the game cameras?