Judy Devenow pleaded guilty to fraud and conspiracy charges Tuesday in federal court in Michigan. She was arrested in January and charged with participating in a complex pump-and-dump stock scam that flogged Chinese penny stocks.

With her guilty plea, Devenow has agreed to cooperate with the U.S. Department of Justice as it pursues its case against 10 other people, including Ralsky, who were allegedly involved in the scam. "She felt it was in her best interest to dispose of this case in this way and not go through a trial," said her attorney, Richard Zuckerman, of Honigman Miller Schwartz and Cohn.

Devenow is facing 33 to 41 years in prison on the charges, but the sentence could be reduced if the government feels she has fully cooperated, he said.

Ralsky claims he is a legitimate business operator, but antispam advocates have long considered him one of the world's most prolific junk e-mailers.

The Department of Justice that Ralsky and others used a botnet network of infected computers to send out tens of millions of spam messages per day.