a simple harassment case

Good luck getting law enforcement to do anything. You will probably need to do you own investigation. If they are serious threat, you should consider contacting law enforcement. You could also contact the site and see if they will do a good deed and cut off the person. Also, you could change you contact information.

This post should not be considered nor relied upon as legal advice since it is only intended for general overview and informational purposes. Please consult with an attorney on your specific situation in order to determine an appropriate legal course of action.