https://www.theguardian.com/technology/2017/aug/03/researcher-who-stopped-wannacry-ransomware-detained-in-us

Marcus Hutchins arrested at Las Vegas airport by the FBI, according to a US Marshal spokesperson, after attending annual DEF CON hacking conference

US authorities have detained Marcus Hutchins, the 23-year-old British security researcher who stopped the WannaCry outbreak in its tracks by discovering a hidden “kill switch” for the malware.