I would send the neighbors and the law a letter (certified to the neighbor) warning them that their dog has been aggressive towards you and that action needs to be taken by them to prevent it from coming to your property again. That way you have it all in writing in case there is a repeat offense.
At that point it would be a VERY dead dog, and the body would just quietly disappear.
An idea for the bad dog....do you have some really, really stinky poo? Guinea poo comes to mind. That stuff is really rank. Nothing like milking a goat that slept under the beam the guinea decided to roost on for the night.
Make friends with the dog and then use rubber gloves and really rub the poo deep within his fur. On his face, back, sides, under and on his collar. Say nothing. When the neighbor comes to ask, shrug and say yes, dogs do love to roll in stinky stuff and you have this guinea and their dog really seems intrigued by the poo. (Notice I did not lie....) A stinky diaper would work, too. Leave a trash bag out with just one tempting item in it so you can say their dog got into your trash. Meanwhile, rub the worst diaper contents you can get on him.
Hubby shot our one dog with a paintball gun for getting in the garbage. She hasn't been in the garbage since. And she is the hunting dog--the one who gets excited every time you bring out a gun. Every gun except the paintball gun, that is. It works, and fwiw, it is worth the money to get one and a tube of paintballs. (at least to us)