Mark Vartanyan, a Russian national and cybercriminal operating under the alias "Kolypto," pleaded guilty to one charge of computer fraud in US federal court in Atlanta, reports the AP.

Vartanyan admitted involvement with the "development, improvement, maintenance and distribution" of the Citadel Trojan between 2012 and 2014 from Ukraine and Norway, from where he was extradited in December 2016. Threat actors could use Citadel to steal victims' financial information and other personal data.

The Trojan has infected an estimated 11 million computers and caused more than $500 million in losses. Cybercriminals used it to target major government and financial organizations worldwide.

Vartanyan, who was charged in the US after being extradited from Norway, is set to be sentenced June 21. He is the second person to be charged in a case related to Citadel: The first was Dimitry Belorossov, who was sentenced to 54 months for attacking computers with Citadel through a botnet he operated from Russia. 

Read more on the AP.