Does Died have an opinion of, or some pull with, the sheriff? If you confront the trespassers and let them know you have photographic proof, they will look for and find the cameras.
If the one guy is in fact the nephew of tour neighbor, he has been put on notice and obviously doesn't care or respect where the property lines are.
You may want to call the county prosecutor to see what they are willing to seek with charges.
One other thing to consider is getting restraining orders against the culprits. Then if you get pictures of them trespassing, the penalty could be far worse than those for trespassing.
