Maybe someone at your insurance company might be able to help? Have you seen your car and the car in question parked side by side in their spaces? You could usually tell pretty easily where the area is on the other door that is coming in contact with your door. Do you know your neighbors? As for a surveillance camera, I would say to look on line for that type of thing. I know people set up surveillance cameras all the time when something like you are talking about is going on. As for liability, contact the police department, or the attorney generals office of your state. If it is your neighbor doing that, and it's continual, I'd say someone needs a brain/courtesy check! What did your landlady tell you about talking to the neighbors?
"Happiness can only come from inside of you and is the result of your love. When you are aware that no one else can make you happy, and that happiness is the result of your love, this becomes the greatest mastery of the Toltecs: the Mastery of Love." ~~don Miguel Ruiz~~