I disagree with poison. Too many unintended victims. I also don't like to call Animal Control. In my experience, all they do is rent you a trap and (and this has happened--I saw it) go to the owner and pocket cash in exchange for not taking the animal to the pound and following those procedures. So, you have to decide for yourself what you are able to do: Can you buy a trap, trap it and then dispose of it? Can you shoot it, without causing undue trauma and/or damaging nearby properties? Can you install better barriers? Stating the obvious, yes, it is the owners responsibility but so what? They don't behave like responsible pet owners. Be careful that you don't anger someone who will then try to get revenge. (Really, a responsible pet owner is one you don't have to worry with; it's the irresponsible ones that will come back to haunt you). You'd be surprised at what Animal Control will do to you--if I shoot my pet they can charge me with animal cruelty, but it's okay to take it to the vet to put it down (kaching). Do what you feel comfortable doing and keep it on the quiet.