Earlier this month, news organizations around the world, including the Times, the BBC, and Le Monde, began publishing stories about corruption involving Isabel dos Santos, Africa’s richest woman. Dos Santos has always maintained that she is a self-made billionaire, but her father, José Eduardo, was the President of Angola between 1979 and 2017, and the bulk of dos Santos’s fortune derives from stakes in Angolan banks, diamond companies, a telecom company, and a cement business. From 2016 to 2017, dos Santos was the chair of Sonangol, Angola’s state-owned oil company.

The revelations this month, known as “Luanda Leaks,” stem from a cache of more than seven hundred thousand documents, including e-mails, spreadsheets, bank transfers, and organizational charts. The International Consortium of Investigative Journalists (I.C.I.J.), which handled the data, described it as “a tale of insider dealing on an epic scale.” Prosecutors have reacted swiftly. The Angolan authorities have accused dos Santos and her husband of embezzling more than a billion dollars from the state, including thirty-eight million dollars in fees, which she authorized during her final hours in charge of Sonangol. Last week, the country’s Attorney General, Helder Pitta Groz, travelled to Portugal, where dos Santos has conducted much of her business, to explore seizing her assets. A banker in Lisbon who worked closely with dos Santos has committed suicide.

On Monday, lawyers for Rui Pinto, a thirty-one-year-old Portuguese hacker, revealed that he was the source of Luanda Leaks. Until now, Pinto was known only as the man behind Football Leaks, a monumental data set—harvested in the course of more than three years—describing the previously unknown financial side of European soccer. I wrote about Pinto and Football Leaks for The New Yorker last year. I spent time with Pinto in Budapest, where he was based for several years. Pinto defies the conventional definition of an activist, a whistle-blower, or a cyber criminal. He worked as an antiques dealer. The soccer clubs, lawyers, and agents that Pinto targeted during Football Leaks portray him as a rogue hacker who used sophisticated phishing techniques to trick his way into their servers and download confidential information. On the other hand, the data that he uncovered has led to dozens of prosecutions for tax evasion and investigations, by UEFA, into some of Europe’s leading clubs. Only a small proportion of Pinto’s data hoard—four of twenty-nine terabytes—was ever systematically processed for Football Leaks. He struck me as clever and anarchic, with an absolute moral distaste for wrongdoing in the real world, but not so bothered about infiltrating your Gmail account.

Luanda Leaks appears to have been a side project. During the weekend, I spoke to William Bourdon, Pinto’s lead lawyer. Bourdon has represented Edward Snowden and campaigns for whistle-blowers and transparency around the world. In 2017, Bourdon helped to found the Platform to Protect Whistleblowers in Africa (PPLAAF), an N.G.O. based in Paris that helped bring down Jacob Zuma, the former South African President. In the summer of 2018, when Pinto asked Bourdon to be his lawyer, Bourdon told him about PPLAAF. “He understood what I did with my new N.G.O., and he could see he could be useful for PPLAAF to get this,” Bourdon said, of Luanda Leaks.

Bourdon didn’t specify how or when Pinto came across the dos Santos documents, only that he found them during his forays into Portuguese soccer. “It was not his target; it was not his purpose,” Bourdon said. “It happened more or less by random, because of the common community between Angolan circles and the Portuguese football industry. The same people, same banks, same lawyers.” In either late 2018 or early 2019, Pinto handed Bourdon a hard drive. “He didn’t know exactly what was in the disk. He knew it was to do with the criminal world,” Bourdon said. PPLAAF subsequently shared the data with the I.C.I.J.

Pinto is currently in prison in Lisbon, awaiting trial on ninety-three charges, including cybercrime and extortion, for offenses allegedly committed during the collection of the Football Leaks data. He faces a maximum sentence of twenty-five years. Portugal has some of Europe’s weakest protections for whistle-blowers, and Pinto’s supporters believe that he is being prosecuted so severely in part because he exposed potential corruption at Benfica, the country’s biggest soccer club. Bourdon told me that he hoped the Luanda Leaks will help to change the perception of Pinto in his home country, where he is a household name. “It’s clear that it will be more and more a public-opinion battle,” Bourdon said. “I hope it will reshuffle the cards.” Pinto’s Portuguese lawyer, Francisco Teixeira da Mota, who will represent him when he goes on trial this spring, said that Luanda Leaks would strengthen Pinto’s claim to be acting in a wider public interest. “It is clear that he is not someone who is seeking profit from his information,” da Mota told me. “And it is clear that his information has great, great value in a civic way, in exposing illegal and very serious things against the people of Angola and Portugal.”

When I was reporting on Football Leaks, Bourdon told me that all citizens should have the right to whistle-blower protections if they obtain evidence of illegal behavior in any field. “I understand that it is a source of anxiety, of trouble and interrogation,” he said. He predicted that the next generation of whistle-blowers would not necessarily have any ties to the industry or political administration that they sought to expose—just the digital savvy to unlock their secrets. “This kind of whistle-blower, these are the ones who are perceived as the worst enemies of the oligarchy,” Bourdon said. “They are the most dangerous, because they can come from nowhere.” During the weekend, he returned to the theme. “Pinto is the Snowden of international corruption now,” Bourdon said. “This young, smart guy, he has this skill. And he is in jail in a democratic country.”