John Stamos John Stamos

John Stamos' attorney denies the actor had a fling with a then-17-year-old girl in 2004 who is now accused of trying to extort the star by threatening to sell compromising photos of him.

Defense lawyer Sarah Henderson made the allegation during opening arguments Monday in the trial of Allison Coss, 24, and Scott Sippola, 31, both of Marquette, Mich., who are charged with conspiracy to commit extortion, according to The Associated Press. Coss and Sippola are accused of attempting to extort the actor for $680,000, claiming they had photos of him with strippers and cocaine. Prosecutors say the photos don't exist, and FBI agents testified Monday they found no such photos during a search of the defendants' house after their arrest, the AP reports.

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Stamos, who is expected to testify, did not comment after Monday's trial, but his attorney, William Sobel, issued a statement through Stamos' rep denying the defense's claim: "The allegations made today in the courtroom by the defendants' attorney during opening statements will not be proven because they are simply untrue."The presiding judge ruled last week that testimony about whether the Full House

star had an intimate relationship with Coss will not be allowed, according to the AP, but opening statements are not testimony and can't be considered by jurors as evidence.

Henderson and Assistant U.S. Attorney Maarten Vermaat agreed that Coss and Stamos met in Orlando, Fla., in 2004, shortly after Stamos separated from wife Rebecca Romijn. Henderson said that Stamos invited Coss and another girl, both of whom he had met at a club, to his hotel room, where he ordered Coss a drink even after she told him she was 17. Two strippers later arrived with cocaine, and Coss and her friend took a photo of Stamos bending over a table with cocaine on it, Henderson said.

John Stamos target of extortion attempt, rep says

Later that night, Henderson said the two kissed on a bed and went into a hot tub, with Stamos undressed and Coss in her underwear. Stamos offered to perform oral sex on Coss, but she declined, Henderson said. According to Florida law, it is a second-degree felony for anyone 24 or older to have oral sex with 16- or 17-year-olds.Stamos got mad and broke a bedpost, but apologized and invited Coss to spend the night, which she did, Henderson said. The two maintained a flirtacious e-mail correspondence for a few years, she said. Vermaat said the e-mails did not discuss the alleged 2004 encounter.Last fall, Stamos received e-mails from a "Jessica T," who claimed the actor was the father of her unborn baby, and from a "Brian L" threatening to extort him with the alleged photos, Vermaat said. Prosecutors believe Coss and Sippola sent the e-mails.

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Henderson said Coss was "Jessica T" and that the e-mails were meant to see if Stamos was preying on young girls. The defense said Coss and Sippola had a right to try to sell photos to Stamos, saying it was a business transaction.In November, Stamos, 46, contacted FBI, who arrested Coss and Sippola at a money drop set up by an FBI agent posing as a representative for Stamos.