A Budapest court is set to decide on Tuesday on the extradition of a hacker linked to the Football Leaks whistleblower website that has exposed alleged corruption, sparking investigations in several European countries.
Rui Pinto, 30, was detained on a European arrest warrant issued by his native Portugal on January 16 in the Hungarian capital where he lives.
He has been held under house arrest for more than seven weeks awaiting a decision by the city's Metropolitan Court on a Portuguese request for extradition.
Pinto is suspected by prosecutors of "aggravated attempted extortion, illegitimate access and theft of data from some institutions, including the state itself".
His lawyers have said he is an "important part" of the Football Leaks website, which has published a series of revelations about alleged wrongdoing in the football world.
The website entrusted millions of pirated documents to a consortium of several European media organisations.
Nicknamed "John" by journalists who combed through the documents, Pinto is "optimistic" that he will avoid extradition, one of his legal representatives David Deak told AFP on Monday.
Released in two segments, the first at the end of 2016 and the second in November 2018, the documents exposed alleged football-related tax evasion, notably by Cristiano Ronaldo when he was at Real Madrid.
Other revelations alleged Uefa had helped Paris Saint-Germain and Manchester City get around the Financial Fair Play (FFP) rules that are meant to regulate clubs' spending.
Pinto is also suspected of being behind a leak of internal emails at Lisbon's Benfica which led to fraud allegations and a corruption lawsuit involving Portugal's most successful club.
After his arrest Pinto's French lawyers described him as "a young Portuguese man who loves football and who, out of disgust at practices that he gradually became aware of, decided to reveal to the world the extent of criminal practices which not only affect the football world but do grave damage to its image".
"These are the Football Leaks revelations which over several years have given rise to the publication of crucial information, resulting in several investigations," the lawyers said.
Slight in stature with an air of youth and spiky brown hair, he is described by those who know him as "sociable and happy", according to information obtained by AFP from The Signals Network, an American foundation for whistleblowers.
According to media reports in his home country, Pinto, an FC Porto and Cristiano Ronaldo fan, is a self-taught IT expert who has been living in Budapest since early 2015.
The Portuguese arrived in the city on an exchange programme as part of his history studies, saying his homeland no longer provided "any prospect because of the economic crisis".
After establishing himself in Hungary, where he earns a living by helping his father, a retired shoe-maker, in the antique business, Pinto created the whistleblower website in 2016.
He started by uploading player and coach contracts belonging to Sporting Lisbon and the Malta-based branch of the hedge fund Doyen, which has attracted scrutiny for alleged dubious practices regarding the management of athletes' careers.
It was in relation to these events that Pinto, suspected of wanting to blackmail Doyen, was arrested in the Hungarian capital.
The Portuguese magazine Sabado was the first to reveal his identity in September and linked him to the Football Leaks website.
His lawyers claim the former Porto resident has been the subject of numerous threats from those who seek to suppress him.
In an interview with the Expresso newspaper last month Pinto claimed Portugal are seeking his extradition from Hungary "to silence what's on my laptop".
He told the Portuguese weekly that he believes his home nation wants to "sabotage" investigations he is assisting in various European countries following the incriminating revelations.