The material in the Donald Trump dossier that emerged this week has been described as unsubstantiated, and the president-elect himself derided the report as “fake news.” However, at least some in the U.S. intelligence community believed that the source of the report was credible, and with the recent unmasking of that source’s identity has come a basis for that credibility.

The man behind the dossier is a former British spy, Christopher Steele, who is now a corporate intelligence consultant. In 2010, Steele helped deliver information about FIFA to the FBI that eventually led to indictments of many current and former officials of the soccer governing body, as well as the ouster of longtime FIFA president Sepp Blatter.

Reuters reported Thursday that it had viewed emails showing that Steele met with members of the FBI’s “Eurasian Organized Crime” squad. The ex-spy’s London-based consulting firm, Orbis Business Intelligence, had been hired in 2009 by England’s Football Association to investigate allegations of corruption by FIFA.

England had been hoping to host either the 2018 or 2022 World Cup, but FIFA awarded those tournaments to Russia and Qatar, respectively, amid accusations of bribery and other corrupt dealings. With FIFA based in Zurich, the U.S. worked with Swiss authorities to investigate the body, and has brought indictments against more than 30 people in an ongoing probe.

“The betrayal of trust set forth here [in the indictments] is outrageous,” Attorney General Loretta E. Lynch said in December 2015, after Swiss police carried out a pre-dawn raid of FIFA officials in Zurich, the second time they had done so that year. “The scale of corruption alleged herein is unconscionable.”

Blatter, who headed FIFA for 17 years, was not among those indicted, but in 2015, he received an eight-year ban from the soccer body by its own ethics committee. In December, the ban on the 80-year-old was reduced to six years, but he faces a separate ethics proceeding as well as a Swiss investigation into the awarding of the 2006 World Cup and its TV rights.

Reuters cited “U.S. officials” in reporting that it was Steele’s “work on corruption in international soccer that lent credence to his reporting on Trump’s entanglements in Russia.” With the revelation that he was the person who assembled the dossier on the president-elect, Steele has fled his home, about 40 miles from London, and gone into hiding.

(H/T Deadspin)