1. He originally submitted the question using his real name before quickly changing his user name to "frosty." Oops, too late.

2. Forensic testimony in the complaint asserted Silk Road used this method and in fact used code identical to that in the answer.

3. Silk Road server encryption was signed with Frosty@Frosty.

#2 and #3 were evidentiary, but #1 is what tied everything to a real person's name.