Sigurdur Ingi Thordarson (Icelandic: Sigurður Ingi Þórðarson) (born 1992), commonly known as Siggi hakkari ("Siggi the Hacker"),^[1][2] is an Icelandic convicted criminal and FBI informant against WikiLeaks.^[3][4][5] He is known for information leaks, multiple cases of fraud and embezzlement, sexual solicitation of minors and adults.^[6][7][8] He has multiple convictions for sexual offences.

In 2010, at the age of 17, he was arrested for stealing and leaking classified information about Icelandic financial companies.^[9] After his arrest, Kristinn Hrafnsson introduced him to Julian Assange, the editor and founder of WikiLeaks, and he worked as a volunteer for the organization between 2010 and 2011.^[10] In 2011, Thordarson contacted the FBI and offered to become an informant, turning over numerous internal WikiLeaks documents and hard drives in the process.^[3] WikiLeaks accused him of having embezzled $50,000 from the WikiLeaks online store to which he pleaded guilty along with other economic crimes against other entities.^[10][11][12] He was also accused of using Julian Assange's name in legal documents.^[13]

In June 2021, in an interview with Icelandic newspaper Stundin, Thordarson recanted some of the previous accusations he had made against Julian Assange. Stundin said the accusations were used in the American indictment against Assange, but The Washington Post disagreed.^[14][15]

Thordarson grew up middle-class in Reykjavik with a younger sister.^[16][17] He began hacking at age 12 and joined WikiLeaks in February 2010 when he was 17 years old and in high school.^[3][17] He went to university to study computer science and psychology, but says he was suspended for hacking.^[16]

Thordarson began leaking information about the Icelandic banking system to the media in late 2009. This included information about individuals in the Icelandic banking system, information that showed that individuals were committing illegal acts in relation to banking. One of the leaks by Thordarson concerned a case called "Vafningsmálið."^[18] It involved Bjarni Benediktsson during his time as an MP. Bjarni reported that the case was only a political smear campaign.^[19] The information published by Icelandic news media obtained from Thordarson also showed that one of the country's biggest football stars, Eiður Guðjohnsen, was deeply indebted and almost bankrupt.

After the information was published, Eiður sued the local newspaper DV for publishing this information. DV lost the case in a lower court, but won an appeal to the Supreme Court of Iceland, stating that the information was a matter for the public.^[20][21] Amongst other information that Thordarson admitted to have leaked in an interview with the Rolling Stone magazine^[17][22] was information about local businessman Karl Wernersson. He was the owner of the Milestone ehf that was the investment company from which Thordarson stole most of the information. Other names in the documents leaked by Thordarson included information about Birkir Kristinsson, who had recently been convicted of economic crimes while working for Glitnir bank.^[23] Some speculate that information from Thordarson was used as evidence in that case, Thordarson also leaked a classified report about one of the bigger aluminum plants in Iceland. The report stated that the plant was paying 1/4 of what other aluminum plants in the world are paying for electricity.^[24][25]

Other information leaked by Thordarson contained information about other local business men such as Gunnar Gunnarsson,^[26] who also has been reported to assist football star Cristiano Ronaldo in tax affairs.^[27] Kristinn Hrafnsson thought Thordarson's leaks were "quite significant" and introduced him to Julian Assange.^[17] In 2013, Thordarson argued with Birgitta Jónsdóttir on Twitter over the release of the loanbooks of the Glitnir Bank. Thordarson said she had no involvement, but he claimed that he had given her the files years ago.^[28] In 2009, Thordarson arrived at the offices of the Special Prosecutor, who investigated the bank collapse in Iceland in 2008. Thordarson reportedly gave them all the information he had on Milestone and other local business men, however instead of using some of the information obtained from Thordarson in investigation the investigators decided to sell the information.^{[29][30][31][32]} The case against the two police officers was later dismissed, and it has been reported that the investigators made roughly 30 Million ISK ($250.000) from the documents.

Thordarson began working for WikiLeaks as early as February 2010 and was fired in November 2011.^[3] In a few weeks, Thordarson was in Assange's inner circle. According to one former volunteer, "the perception was that Siggi basically got to a level where Julian trusted him in a matter of days."^[17] Birgitta Jónsdóttir, a former WikiLeaks volunteer and member of the Icelandic parliament who worked on Collateral Murder, described Julian Assange's relationship with Thordarson as like "Batman and Robin."^[17] Several of WikiLeaks' core volunteers said that Siggi was a dangerous liability, prone to indiscretions and lies and Jonsdottir warned Assange not to trust Thordarson.^[3][17][33] Assange told others not trust or talk to Thordarson, but continued working with Thordarson. According to Daniel Domscheit-Berg, "it all implied Julian was using him. These are all kinds of games children get into."^[17]

Assange helped Thordarson find a lawyer in 2010 after he was arrested, and directly gave Thordarson an encrypted cell phone, and involved him in the Collateral Murder project.^[16][17] Assange asked Thordarson to write psychological profiles of core WikiLeaks members and to install hidden cameras to spy on guests in Ellingham Hall. Thordarson performed additional surveillance and copied their hard drives.^[17] They talked regularly and Thordarson looked for equipment and made encrypted calls to contacts on Assange's behalf.^[17] According to an indictment against Assange, he and Thordarson made a "joint attempt" to decrypt a file stolen from an Icelandic bank.^[34]

Thordarson took part in moderating a chat room, vetting potential allies and sources.^[17][35] Reports state that Thordarson obtained many leaks that WikiLeaks later published, such as The Kissinger cables, The Syria Files, and the Stratfor emails^[3][16][36] and journalists said he was involved in delivering the leaked diplomatic cables to journalists.^[17] He also sold T-shirts for the organisation and was the middle man in negotiations that led to WikiLeaks donating $15,000 to Chelsea Manning's defense fund.^[3][11][35]

David Kushner reported that Thordarson provided Rolling Stone with over 1 terabyte of data about WikiLeaks, including thousands of pages of chat logs, videos, tapped phone calls, government documents. Kushner said that either Thordarson was the real deal or this was the biggest and most elaborate lie in the digital age, and that Assange's affidavit validated the importance of Siggi’s documents.^[17] Tangerine Bolen, founder of former WikiLeaks collaborator RevolutionTruth, said WikiLeaks' efforts to discredit Thordarson after his FBI cooperation became public were patently false. They’re scared. The fact is Siggi played a key role in the organization and was very close to Julian."^[17]

Thordarson embezzled $50,000 from a WikiLeaks online store that sold T-shirts, the money was paid into his own bank account and the official reason why he was fired.^[3] Thordarson said he used the funds to cover expenses he was owed by WikiLeaks and that the money went through his account with Assange's permission.^[16][17] Thordarson was later convicted on a related charge.^[10][11][12]

In January 2010, when Thordarson was seventeen years old he was arrested on suspicion of stealing classified information from Milestone ehf. That case never reached the court system and Thordarson described his involvement in the Rolling Stone interview.^[9][17]

In 2012, Thordarson was questioned about sexual misconduct, accused of deceiving a seventeen-year-old teenage boy.^[67][2] At the time, Thordarson was 18 years old. Thordarson denied the charges but was found guilty in late 2013 and received 8 months in prison.^[67][2]

In 2012, WikiLeaks filed criminal charges against Thordarson for embezzlement. Thordarson denied the charges and the case was later dismissed. He was later arrested in the summer of 2013 on charges of financial fraud. At that time, the WikiLeaks case was brought back up, and Thordarson was indicted on charges of embezzlement and financial fraud. In 2014, Thordarson was ordered to pay WikiLeaks 7 million ISK (roughly $55,000) as well as being sentenced to prison for 2 years for embezzlement and financial fraud. Thordarson pled guilty to all counts.^[13][68] In those cases Thordarson was ordered to pay the victims 15 million ISK (roughly $115.000),^[13] Thordarson received a two-year prison sentence in those cases.^[12]

In 2012, Thordarson was arrested for allegedly having tried to blackmail a large Icelandic candy factory, but the case was later dismissed.^[69]

In January 2014, Thordarson was again arrested for sex crimes. He was believed to be a potential flight risk as well as being likely to sabotage the investigation against him and therefore placed in solitary confinement.^[70] Thordarson had said he would offer flight tickets, Land Rovers, and up to a million dollars in exchange for sexual favours.^[71] The victims ranged from the age of 15–20, all male, during which Thordarson was 18–21. A psychiatric evaluation ruled that Thordarson was of sound mind, but that he had an antisocial personality disorder^[71] and was incapable of feeling remorse for his actions.^[14] Thordarson pled guilty to all counts and received a 3 year jail sentence.^[72][70][73]

Thordarson was ordered to pay 8.6 million ISK (roughly $66,000) in damages to his victims.^[74][75][71] In 2014, he was sentenced to pay roughly $236,000 in damages for various economic crimes and frauds, including having swindled fast-food companies, car rentals, electronics shops, and having tricked someone into giving him all his shares in a book publishing company.^[2] In September 2015 he was sentenced to three years' imprisonment for having sex with nine underage boys, after confessing to the crime the previous month. The victims were offered payment or some other form of inducement.^[4] A court ordered criminal forensic psychiatric evaluation diagnosed him with antisocial personality disorder.^[71]

In September 2021, on the day he returned to Iceland from a trip to Spain, Thordarson was arrested and imprisoned. He is being held indefinitely under an Icelandic law enabling the detention of individuals believed to be active in ongoing crimes. According to Stundin, the cases leading to his arrest involved financial fraud.^[76]

In 2021, new details became public.^[77] These included allegations from one of his victims that Thordarson assaulted him more than the 40 times the court judgment said. According to the victim, Thordarson had weapons and threatened him and his family over a 2-3 year period, and used pepper spray and a stun gun on him.^[77] Thordarson recorded a video of him and the victim, which the police came into possession of and led to them learning more.^[77]

The film The Fifth Estate (2013), with Benedict Cumberbatch as Assange, features a character based on Thordarson's played by Jamie Blackley.^{[citation needed]} Thordarson is mentioned in Domscheit-Berg's book, during his time with WikiLeaks he reportedly used the handles PenguinX, Singi201 and "Q".^[78]