My personal opinion is this is not Law Enforcement.  Just a distressed hobbyist.

You should probably be more diligent with your screening for the next few weeks.  My bet is that this is an idiot that's trying to get under your skin.  Another suggestion is to post warnings on the ladies board, and perhaps blacklist as well.  While it's possible it's LE, more likely you are dealing with an idiot that you had best ignore for now.

those cray people; the more you answer, the more they get excited and will harrass you. Report his email as spam, and all his email will go to the spam file and ignore them then.

.. that will only encourage this person, who by the way is not the Law. IF it was they would arrest you not harass you with emails.