Sigurdur Thordarson

Early Life

Sigurdur Ingi Thordarson was born in 1992 and grew up middle-class in Reykjavik, Iceland, with a younger sister. He began hacking at the age of 12. He joined WikiLeaks in February 2010 while still 17 years old and in high school. He later enrolled at university to study computer science and psychology but says he was suspended for hacking.

Information Leaks

Beginning in late 2009, Thordarson began leaking information about the Icelandic banking system to the media. The leaked material included evidence of alleged illegal acts by individuals connected to Icelandic financial institutions. Among the subjects of his leaks were politician Bjarni Benediktsson, football star Eiður Guðjohnsen — whose reported financial difficulties led to a legal dispute with the newspaper DV that was ultimately resolved in DV's favor by the Supreme Court of Iceland — and businessman Karl Wernersson, owner of Milestone ehf, from which Thordarson stole much of the information. Other leaked documents touched on businessman Gunnar Gunnarsson and a classified report about an Icelandic aluminum plant's electricity costs. In January 2010, Thordarson was arrested on suspicion of stealing classified information from Milestone ehf, though that case did not reach the court system.

Kristinn Hrafnsson, who considered Thordarson's leaks "quite significant," introduced him to Julian Assange, the founder and editor of WikiLeaks.

WikiLeaks Involvement

Thordarson began working for WikiLeaks as early as February 2010 and was fired in November 2011. Within weeks of joining, he had reached Assange's inner circle. Birgitta Jónsdóttir, a former WikiLeaks volunteer and Icelandic parliamentarian, described the relationship between Assange and Thordarson as like "Batman and Robin," though she and several other core WikiLeaks volunteers warned Assange that Thordarson was a dangerous liability prone to indiscretions and lies.

During his time with WikiLeaks, Thordarson was given an encrypted cell phone by Assange, was involved in the Collateral Murder project, and was asked to write psychological profiles of core WikiLeaks members and to install hidden cameras at Ellingham Hall. He moderated chat rooms, vetted potential sources and allies, and served as WikiLeaks' contact with hacker groups including Anonymous and LulzSec. He is reported to have been involved in obtaining leaks later published by WikiLeaks, including the Kissinger cables, the Syria Files, and the Stratfor emails. He also acted as an intermediary in negotiations that led to WikiLeaks donating $15,000 to Chelsea Manning's defense fund.

Thordarson embezzled $50,000 from a WikiLeaks online store, depositing the funds into his own bank account. This was the official reason for his dismissal. He claimed the money covered expenses owed to him by WikiLeaks and that it passed through his account with Assange's knowledge. He was later convicted on a related charge.

Reports also indicate that Thordarson ordered DDoS attacks on Icelandic governmental infrastructure, including servers hosting Ministry websites, and that he directed Hector Monsegur (known as Sabu of LulzSec) and his team to attack Icelandic State Police servers.

FBI Cooperation

In August 2011, Thordarson contacted the United States Embassy in Reykjavik, claiming to have information relevant to an ongoing US criminal investigation. The following day, the FBI dispatched a private jet carrying eight federal agents and a prosecutor to question him. After Icelandic authorities learned that the questioning extended to WikiLeaks matters, the FBI was asked to leave Iceland. Thordarson accompanied the agents to Denmark, where questioning continued.

Through 2012, Thordarson met with federal agents on multiple occasions in Copenhagen and Washington D.C., handing over several hard drives he had copied from Assange and core WikiLeaks members. He reportedly received $5,000 in compensation for time missed during these meetings. In May 2019, he signed an immunity agreement with US prosecutors and is referred to as "Teenager" in the indictment against Assange.

In June 2021, in an interview with the Icelandic newspaper Stundin, Thordarson recanted portions of his earlier testimony, stating, for example, that Assange had not instructed him to hack or access phone recordings of Icelandic MPs. Several news organizations, including Deutsche Welle, Der Spiegel, The Hill, and The Intercept, described Thordarson as a key or chief witness in the US case against Assange. The Washington Post, however, reported that his testimony was not the basis for the core charges. A 2024 documentary, A Dangerous Boy, directed by Ole Bendzen and produced by Søren Steen Jespersen, alleged that the Stundin article recanting his testimony had been orchestrated and funded by WikiLeaks. Thordarson has stated on his personal website that he does not admit to lying anywhere in the article or in recordings of the interview, and that the claim appears only in the headline.

Arrests and Convictions

Thordarson accumulated multiple criminal convictions across several years. In late 2013, he was found guilty of sexual misconduct involving a seventeen-year-old and received an eight-month prison sentence. In 2014, he was sentenced to two years in prison for embezzlement and financial fraud, including the WikiLeaks embezzlement, and was ordered to pay approximately $115,000 to victims and roughly $55,000 to WikiLeaks. He was also sentenced to pay approximately $236,000 in damages for a range of economic crimes including fraud against fast-food companies, car rentals, and electronics shops. In September 2015, he received a three-year prison sentence after confessing to paying or offering gifts for sexual favors involving four boys under the age of 18 and acquiring prostitution from five adult men. A psychiatric evaluation found him to be of sound mind but diagnosed him with antisocial personality disorder and noted he was incapable of feeling remorse.