Crazy Situation

I've never had this happen to me before, but I think I am possibly being stalked by a missing person. I've stumbled upon the fact that I think she is a missing person, and I have tried three times to get the police to come and pick this person up, but all three times the police never came. Finally, she showed up at my door again today wanting to 'talk' to me. My brother, who is a magistrate, said that I should call 911 and leave the phone off the hook. He said the police should come then. I also noticed that a letter I had put in the mailbox (a letter to my brother, in fact) for the mailman to pick up was missing. I know that she took it, because the letter was out there when she came, but it was gone when she left. The mailman didn't pick it up (in case you were thinking that), because a) he doesn't come that early and b) I was on the front porch when he pulled up! He handed my mail right to me, but of course, there was nothing for him to take, because she had taken that letter. I've gotten others involved, and I have pointed her to some helpful resources, and have even helped her myself (which opened the door to this crazy situation), but now I'm not so sure what I've gotten myself into. She calls incessantly. The phone rings and rings...12 times an afternoon, it's crazy. I'm a little concerned.