He was apparently really careful about connecting to the server. The docs state that he logged in through a VPN provider and he logged into the VPN provider at an internet cafe (which was apparently close to his house).

However, the document doesn't seem to state who the VPN provider was or if he was the customer tied to the VPN account (probably avoids this info because the VPN is account is in someone else's name). So again, can't prove via this route that it was him.

I'm curious to know how they managed to find the Silk Road server though..