The recent arrest of someone behind Silk Road is in the news today, he was arrested in a San Francisco public library. A couple of background articles [here](http://www.businessinsider.com/silk-road-stack-overflow-post-2013-10) and [here](http://www.forbes.com/sites/alexkonrad/2013/10/02/feds-shut-down-silk-road-owner-known-as-dread-pirate-roberts-arrested/).

To what extent, if any, did staff and/or admins have in assisting law enforcement agencies in arresting this programmer? Did they voluntarily cooperate, or was it a legal requirement to cooperate under US law? 

An answer from some authority saying Stack Exchange is not able to discuss the issue with users is also acceptable to me.