Updated

A Russian man accused of masterminding a vast worldwide spamming network is due to appear in a Wisconsin federal court.

Oleg (OH'-leg) Nikolaenko (NIK'-oh-lye-ehn-koh) is set to be arraigned Friday morning in Milwaukee.

Prosecutors say the 23-year-old Moscow man ran a network that involved placing malicious code on unsuspecting users' computers and then hijacking the infected machines to blast out billions of e-mails.

Internet-security experts say the network was so massive that on some days it accounted for one of every three unwanted e-mails in the world.

Nikolaenko is charged with violating a U.S. anti-spam act. The charge carries a maximum penalty of three years in prison and a $250,000 fine.

Defense attorney Chris Van Wagner says he plans to mount a "vigorous" defense.