Go to account then click Privacy Settings and Block List  You should end up at a page like this.  Enter his user ID, email, etc.  It is supposed to block him from you.

I suppose if you can't dazzle him with brilliance baffle him with --------.  Privately and quietly tell him,, "Hey! Facebook has been upset because of your actions and if you don't quit they are going to come after you.  I tried to put them off, but they called wanting information about you."  A phone call from a a couple friendly NAT'ers might convince him.

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