“Stay strong Rui Pinto,” read the banner in the Freiburg end during the German side’s 3-3 draw with Wolfsburg last month. More than 1,000 miles east and after a brief hearing on Tuesday, a Hungarian court finally ruled that the 30-year-old who dropped out of his history degree at university and is accused of being the brains behind one of the biggest exposés professional sport has ever seen will be extradited from his home in Budapest.

Pasty-faced with spiky gelled hair, Pinto – who expressed his thanks to supporters of Augsburg and Paderborn on Twitter after they displayed similar banners – doesn’t exactly look like a criminal mastermind. The Football Leaks website has, since being established in September 2015, aired claims about what its creator describes as the “illicit practices that affect the world of football”, whether that is Cristiano Ronaldo’s and José Mourinho’s tax avoidance or the internal emails used to accuse Manchester City of violating Uefa’s Financial Fair Play Regulations.

Nearly three years after Pinto was first publicly named by the Spanish newspaper Marca, he was detained on a European arrest warrant filed by Portuguese police six weeks ago and will now answer charges of “extortion, violation of secrecy and illegally accessing information” in the country of his birth.

“I am nervous because I am a target for attacks, especially by fans of Benfica,” Pinto told the German newspaper Der Spiegel in an interview last month. “Ever since last autumn, I have been receiving massive death threats on Facebook. I am afraid that if I set foot in a Portuguese prison, especially one in Lisbon, I will not leave it alive.”

Pinto has worked under the pseudonym “John” in conjunction with Der Spiegel and other members of the media network known as the European Investigative Collaborators (EIC group), and it is estimated his network has supplied around 70 million documents and 3.4 terabytes of information including personal emails from some of the sport’s most influential figures. “I initiated a spontaneous movement of revelations about the football industry,” he explained. “So, I am not the only one involved. Over time, more and more new sources have been added, who have shared their material with me, and the database grew.”

Robin Wille (@WilleRobin) Gestern in Freiburg:

"Stay strong Rui Pinto"#FootballLeaks

(Bild: https://t.co/1TkVdziW1Z) pic.twitter.com/Fjrq1JqaNQ

Having first revealed third-party agreements between FC Twente and agents Doyen Sports which broke Dutch Football Association rules – a disclosure that led to Twente being banned from European football for three years – it is alleged that Pinto turned his sights on Portugal’s domestic league at the end of 2015. Using what Marca’s report described as “a string of hacking techniques to gather information and leak details related to players’ contracts at a number of teams” that included Benfica, Sporting and Porto, it is alleged that he first attempted to blackmail Doyen by demanding more than €500,000 not to disclose sensitive information related to players represented by the agency before publishing the information on the Mercado de Benfica website, which remains active.

Porto were recently fined 50,000 Swiss francs by Fifa for allowing Doyen to influence the club’s transfers, with a statement from football’s governing body saying the club had “entered into contracts that enabled the third party to have an influence on the club’s independence and policies in transfer related matters”.

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Meanwhile, such were the weight of the allegations published by the Football Leaks website against the likes of figures such as Ronaldo, Mourinho and Lionel Messi over the following 12 months that the European Parliament’s committee of inquiry into money laundering began looking into “epidemic” tax evasion in the game in September 2017, citing the website for prompting its investigation. Another year had passed when Sábado magazine in Portugal ran an exclusive story that revealed local police had identified their chief suspect in the Benfica case as Pinto, describing him as a “computer genius”. A few days later, a post on Football Leaks’ Facebook page seemed to taunt Portugal’s police with the message: “PJ looking for me? LOL #catchmeifyoucan”, although Pinto denies that had anything to do with him.

“It changed my life,” he said of the story. “My photograph was on cover pages throughout the country. My Facebook account, my email address were subsequently inundated with death threats.”

Facebook Twitter Pinterest Documents allegedly relating to Cristiano Ronaldo were obtained via Football Leaks. Photograph: Marco Bertorello/AFP/Getty Images

At the end of September 2018, Kathryn Mayorga went back on the non-disclosure agreement she had signed with Ronaldo’s lawyers and went public with her allegations of rape against the Portugal forward. Key to her case were documents that appeared to support her claims which had been obtained via the Football Leaks website, although Ronaldo’s lawyers subsequently dismissed them as having been fabricated by hackers.

Six weeks later and having remained quiet for more than a year other than a Christmas message at the end of 2017, the publication of a new slew of allegations by Football Leaks last November once more took aim at football’s establishment. The Fifa president, Gianni Infantino, was portrayed as having played a central role in negotiations that led to a settlement when City and Paris Saint-Germain were accused of breaking FFP rules – an allegation that was dismissed as an attempt “to undermine the new leadership of Fifa”. Meanwhile, the elite clubs’ plans for a European Super League to start in 2021 were laid bare in leaked emails sent to Real Madrid’s president, Florentino Pérez. Pinto was eventually arrested on 16 January in Budapest, where he had moved several years earlier as an Erasmus student, after returning from the supermarket with his parents.

“For me it is really strange that it took three years to find someone who they had a picture of and knew where he lived,” says Pippo Russo, a sociologist at the University of Florence who specialises in the business of football. “In my opinion, Rui Pinto is not a criminal – he is a whistleblower and they must be protected at all costs.”

Facebook Twitter Pinterest There were leaked emails sent to Real Madrid’s president, Florentino Pérez, regarding a possible European Super League. Photograph: Juan Medina/Reuters

With the Frenchman William Bourdon – the former lawyer of Edward Snowden – due to represent him, Pinto has insisted “not a single cent was paid” to him during the correspondence with Doyen but admitted he was “naive”. “Looking back now, I regret it,” he said. “But I repeat that I deny having committed any criminal offence.”

With the fallout out far from over, Russo believes there is far more at stake here than just one man’s liberty. “There are a lot of people in football who want to see him in jail and hope that now Rui Pinto has been arrested the leaks will stop,” he says. “But I don’t think stopping only one person will do it forever. It’s wishful thinking.”

Russo adds: “This could be a real milestone for the world of football because it may help to create a legacy for the future that enables other people to come forward to reveal wrongdoing without fear of being prosecuted.”

Yet with the courts having now ruled otherwise, Pinto now faces the jail sentence he so fears.