Marcus Hutchins, the 22-year-old IT expert who helped thwart a global ransomware attack, was arrested in the United States.
Hutchins made international news after he helped stop the WannaCry ransomware threat on a hunch earlier this year. WannaCry infected over 300,000 machines in 150 countries.
He was in Las Vegas for the hacker conferences DefCon and Black Hat.
He was arrested at the airport on Wednesday, a friend told Motherboard. The friend tried to visit Hutchins at Henderson Detention Center in Nevada the next morning, but was told Hutchins had been moved.
“We still don’t know why Marcus has been arrested,” the friend, who was granted anonymity, told Motherboard.
Those who work in the industry say he was taken to an FBI facility.
“We are aware of the situation,” a spokesman for the U.K.’s National Cyber Security Centre told the BBC. “This is a law enforcement matter and it would be inappropriate to comment further.”
U.S. law officials told CNN the charges are related to the creation and distribution of “the Kronos banking Trojan.”
A grand jury indictment was filed on July 12, 2017.
Colleagues of Hutchins have started defending him online.
“To be absolutely clear @MalwareTechBlog‘s business is reversing malware to monitor botnet traffic,” Kevin Beaumont, a security architect wrote on Twitter.
“I know Marcus. He has a business which fights against exactly this (bot malware), it’s all he does.”
The Electronic Frontier Foundation, which says it defends civil liberties in the digital world, says, “We are looking into the matter, and reaching out to Hutchins.”