The very boring truth is the feds probably just put the guy's name, usernames, email addresses etc into Google and got a court order to explore certain results.

The very boring truth is the feds probably just put the guy's name, usernames, email addresses etc into Google and got a court order to explore certain results. People using SO should be aware of how to google something and able to reach such an obvious conclusion - and this probably happened to 100s or 1000s of sites they encountered and in most other cases since MySpace reached critical mass years ago. The only question is whether they pay someone to do it manually or they paid someone like a SO user to automate it.