A Russian national who was arrested earlier this month in Spain has been charged with criminal hacking offences in relation to operating the Kelihos botnet.
Peter Yuryevich Levashov, 36, was indicted late last week by a grand jury in and charged with causing intentional damage to a protected computer and wire fraud, among other counts, the US Justice Department said in a statement.
Last week the Justice Department announced it had launched an effort to take down the Kelihos botnet, which has infected computers that ran Microsoft's Windows operating system, after Spanish authorities arrested Levashov while he was on vacation with his family in Barcelona.
The Kelihos botnet is a global network of tens of thousands of infected computers.
Levashov used Kelihos for years to distribute during any given 24-hour period more than 2500 spam emails for various criminal schemes, including pump-and-dump stock fraud, password thefts and distribution of malware, including ransomware, the indictment alleges.
Levashov remains detained under an international arrest warrant. The Justice Department said it is seeking his extradition to the United States to face charges.
The Russian Embassy in Washington could not be reached for comment. It could not be determined if Levashov has retained a lawyer.
The Kelihos botnet has been a source of criminal activity targeting computer users worldwide since at least 2010, and at times grew larger than 100,000 simultaneously infected devices, a Justice Department official said.
Botnets are often rented out for multiple criminal uses as well.
Russian-state media service RT reported earlier this month that Levashov was arrested in relation to the US government's belief that Moscow interfered in last year's US presidential election to help Republican Donald Trump win.
The Justice Department official said, however, that the Kelihos case was not connected to election hacking, and the indictment makes no mention of it.
Levashov, who has long been considered the likely identity of an online persona known as Peter Severa, spent years listed as among the world's 10 most prolific computer spammers by Spamhaus, a spam-tracking group.