jfreels- try educating your neighbor & maybe try to teach him that you know for sure that the kingsnakes are not dangerous should it or another come crawling back. look up venomous snakes in your area & try to get a good look at the pics so you guys will be able to recognize them should you or your neighbor find one. thats what i'd do anyways.
sounds like your neighbor needs some education on which snakes are good & which are bad.