The Justice Department announced Tuesday a reward of up to $3 million leading to the arrest and/or conviction of the alleged leader of "a tightly knit gang of cybercriminals" who developed the Gameover ZeuS botnet.

Gameover ZeuS siphons passwords to online banking sites from Microsoft Windows computers.

The authorities are offering the reward for Evgeniy Mikhailovich Bogachev, accused of various charges in connection to the botnet. The authorities said the botnet infected more than 1 million computers and resulted in $100 million in losses.

"Although we were able to significantly disrupt the Gameover ZeuS and Cryptolocker criminal enterprise, we have not yet brought Bogachev himself to justice," Assistant Attorney General Leslie Caldwell said.

Bogachev, who according to authorities is believed to be at large in Russia, is on the FBI’s most wanted cyber list.

The authorities have moved to stamp out the exploits. Within a week of last year's takedown of Gameover ZeuS and Cryptolocker, a surge of spam with links to a Cryptolocker copycat known as Cryptowall resulted in a jump in ransomware infections, according to a recent report by security-services firm Dell Secureworks.