Allison Coss, 24, and Scott Sippola, 31, were convicted of conspiracy and using e-mail to threaten a person's reputation after about 4 hours of deliberation, E! News said Thursday.
Coss and Sippola were accused of trying to extort $680,000 from the former "Full House" and "ER" star in exchange for not making public allegedly incriminating 2004 photos of Stamos. The couple claimed they saw the actor go on a cocaine binge, cavort with strippers and try to have sex with Coss, who was only 17 at the time.
"I would like to thank the court, the FBI and the U.S. Attorney's office for their swift and efficient dealings in connection with this case," Stamos said in a statement issued to E! News.
"I am shocked and perplexed how individuals could fabricate so many false stories in an effort to defend a crime," added Stamos. "I agreed to be a witness for a federal criminal prosecution and endured countless false accusations about my behavior and appropriateness."