The federal case, and facts stated by Harkins during his pleas Wednesday, arose from a local investigation based on tips that he was using and selling illegal drugs at his home.
On Wednesday, a Homeland Security Investigations agent began chatting with a person identified as Custeau, who had responded to an ad on an unnamed website.
In a reminiscence, the judge wrote, "I yearn for the day where litigants seek their courts unburdened by the possibility of physical reprisal. That hope may be quixotic today."