On an August workday in 2011, a cherubic 18-year-old Icelandic man named Sigurdur “Siggi” Thordarson walked through the stately doors of the U.S. embassy in Reykjavík, his jacket pocket concealing his calling card: a crumpled photocopy of an Australian passport. The passport photo showed a man with a unruly shock of platinum blonde hair and the name Julian Paul Assange.
Thordarson was long time volunteer for WikiLeaks with direct access to Assange and a key position as an organizer in the group. With his cold war-style embassy walk-in, he became something else: the first known FBI informant inside WikiLeaks. For the next three months, Thordarson served two masters, working for the secret-spilling website and simultaneously spilling its secrets to the U.S. government in exchange, he says, for a total of about $5,000. The FBI flew him internationally four times for debriefings, including one trip to Washington D.C., and on the last meeting obtained from Thordarson eight hard drives packed with chat logs, video and other data from WikiLeaks.
http://www.wired.com/threatlevel/2013/06/wikileaks-mole/