Forgive me for being potentially obvious, but can't you trace every single bitcoin transaction ever? So you can go from: Domain seller -> "Anonymous persons b

Forgive me for being potentially obvious, but can't you trace every single bitcoin transaction ever? So you can go from: Domain seller -> "Anonymous persons bitcoin address" -> Bitcoin address of the person who sold him those BTC. You then find that person (as i'm pretty sure they're not so focused on anonymity) and wrench-attack a description of this guy and location + time of the meet from him (and also the e-mail he sent to arrange it -- tone, etc). CCTV camera footage of the meet/people in that area at the time, etc. Home and dry.