im sorry to hear about this. i would read up firmly on guns laws and be ready
honestly, if it was me...i would try and bait him. buy those cheap infrared camera with motion detection and recording (seen a few setups for 100$ or less online). see if you can get visual evidence of crimes or tresspassing. if you "ballsy", and he is to. i would try baiting him into the house...send wife and kids away on a streak of nights with issues, leave a door open everything else off. make it look enticing to come in the house. then follow your gun laws and rights and solve the problem!