Syria's lethal Facebook checkpoints

An anonymous tip from a highly reliable source: "There are checkpoints in Syria where your Facebook is checked for affiliation with the rebellious groups or individuals aligned with the rebellion. People are then disappeared or killed if they are found to be connected. Drivers are literally forced to load their Facebook/Twitter accounts and then they are riffled through. It's happening daily, and has been for a year at least." Anyone have any corroboration for this?