There have been federal convictions for this—I recall reading about one a few years back when an airline pilot based in Arizona or somewhere was harassing a woman via the Internet, and because it was across state lines he got a nasty sentence in federal court.
A friend of mine, a middle-aged widow, was being stalked and harassed online by a high-school boyfriend she had not seen or heard from in thirty years. He was in California and she was on the East Coast. She shut him down pretty quickly with the threat of federal prosecution. She also had him served for a personal injury lawsuit at his home, in front of his wife. It was hilarious. He was arrested when he showed up in her county. She lives in a state where they don’t like his kind frightening a nice lady and her little children.
I would collect evidence of threats and harassment, as well as communications in which you tell your correspondent to cease and desist. Then go to the US Attorney in your area. If he can’t help you, a personal injury lawsuit doesn’t have nearly the standards a prosecutor has to adhere to.
Thanks for the info. I’m currently putting together the posts. I’ve got people all over the country from various sites who will email me links and keep me apprised of new posts.