Moments after posting this question, Ross Ulbricht changed his email address on Stack Overflow from one in which his name was associated to the fictitious “[email protected]” Stack Overflow keeps track of all previous email addresses used, and when an IRS agent approached Stack Overflow with a subpoena, the company provided the original email address, thereby revealing the identity of the user.

Ross Ulbricht is in jail for life for masterminding the Silk Road website. This Stack Overflow post was a critical clue.1

  1. I highly recommend reading American Kingpin for the full story. ↩︎