The IT researcher who helped stop the spread of the WannaCry malware earlier this year has been indicted by the FBI for his alleged role in creating and spreading an unrelated piece of malicious software between 2014 and 2015.

As first reported by Vice's technology news website Motherboard, 23-year-old Briton Marcus Hutchins was detained by authorities after attending the Black Hat and DEF CON technology conferences in Las Vegas. 

Hutchins was hailed as an internet hero earlier this year for his role in helping to stop the WannaCry malware's spread. The malicious software hijacked 200,000 computers worldwide in May and demanded a ransom in order to release the data

Hutchins was able to help curtail the malware's spread by activating a kill switch in its source code. His solution was to register a specific domain name that was inadvertently buried in the code.

According to court documents, Hutchins was charged before leaving Las Vegas, and a grand jury has indicted him on six counts of conspiracy. He is accused of being behind a trojan horse known as Kronos, which is hidden software that extracts user credentials and personal details from people over secured banking networks.

The U.S. Justice Department said Kronos was used to steal banking  systems credentials in Canada, Germany, Poland, France, the U.K. and other countries.

Between July 2014 and July 2015, he's accused of creating the malware, advertising its existence, and selling it to others, court documents allege.

The Kronos code was advertised on the illegal AlphaBay online marketplace, which was shut down last month.

Reuters reported that a  U.S. Justice Department official said the arrest of Hutchins was unrelated to WannaCry.