Have you taken her picture to the police? They may already know who she is and can pay her a visit, police still like'um jelly filled right? Wait, I didn't mean to type that, that is my old way of thinking. Back on topic: They could pay her a visit and warn her about trespassing.

“If you do not conquer self, you will be conquered by self.” Napoleon Hill
The most difficult thing to understand during conversation is silence. Thoreau