In the specific case mentioned here, where state and Federal law enforcement won't take charge, why shouldn't she find a professional investigator to confirm who the perpetrator is, then use the same tactics he has used against her against him?
After all, law enforcement refuse to take action right? So it appears that law enforcement wouldn't care if she ensured that he is kept out of the picture.
I'm not sure an investigator is the most productive course. If it was me, I'd start with a Cease and Desist letter from a lawyer. Cost: about 2 billable hours. If that fails, since there is, in fact, a law being broken, and now the creeper has ignored a C&D, get a court order. No need to involve police, they can continue writing speeding tickets and tending to other urgent matters. If the creeper ignores the court order, then see if you can get a bench warrant issued. Although, in this case, it sounds like the person is mentally ill -- what you can do about that varies greatly from state to state.
