For three months in 2011 — less than a year after WikiLeaks released its most famous series of documents leaked by Bradley Manning — a mole inside the non-profit organization provided the FBI with chat logs, videos and other data from Julian Assange and his associates.

The mole's name is Sigurdur "Siggi" Thordarson, a longtime Icelandic volunteer working for WikiLeaks at the time. On Thursday, Wired's Kevin Poulsen revealed Thordarson's double role as a close Assange protégé and a paid informant working for the United States government in its WikiLeaks investigation.

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The revelation, which comes directly from Thordarson, gives the public another snapshot into the WikiLeaks investigation. Last week, two former WikiLeaks volunteers revealed that Google handed over their emails to the U.S. government, allegedly as part of the Justice Department's ongoing grand jury investigation into the website.

Thordarson, now 20 years old, approached Wired because Poulsen is "a reporter disliked by Julian Assange," as Poulsen said. He told the Wired reporter that he gave the FBI eight hard drives containing 2,000 pages of chat logs, photos and videos he shot in England while Assange was under house arrest at Ellingham Hall, a country house in the UK.

Thordarson's motives for turning against Assange and WikiLeaks are unclear.

A few months after joining WikiLeaks, he was assigned to manage the site's chat room, making him the point of contact for new volunteers, journalists and potential sources. In that role, he approached members of the hacking group LulzSec in June 2011 to ask them to hack the Icelandic government for WikiLeaks, apparently without asking Assange for permission.

When asked about his motives for collaborating with the FBI, Thordarson said he "didn’t want to participate in having Anonymous and Lulzsec hack for WikiLeaks," since that breaks "quite a lot of laws." However, Thordarson was the one who approached the hacktivist group in 2011. He also said he did it "for the adventure."

WikiLeaks fired Thordarson in November 2011, after the organization discovered that he had created a website selling WikiLeaks t-shirts and embezzled the money to his account, siphoning off about $50,000. He continued collaborating with the FBI afterward; he received $5,000 for his services and flew to Copenhagen and Washington D.C. to meet with his FBI handlers on various occasions.

On Tuesday, the New York Times reported the U.S. investigation into Assange and WikiLeaks is still active, and officials have been gathering materials and questioning witnesses since October 2010.

Assange released a statement to the Times, stating the Justice Department "and its accompanying FBI investigation are blinded by their zeal to get rid of publishers who speak truth to power." He added: "They believe U.S. agencies can flout laws, coerce people into becoming informants, steal our property and detain our alleged sources without trial."

While the extent to which Thordarson aided the WikiLeaks investigation remains unclear, he is dealing with other issues. WikiLeaks filed a police report for his $50,000 t-shirt embezzlement, and he also faces criminal charges in Iceland for unrelated financial and tax crimes.

Image via Anthony Devlin/AFP/Getty Images