An Atlanta man — accused of arranging a sexual tryst with an undercover Peachtree City police officer who posed as a 15-year-old — was convicted of several associated charges by a jury Friday morning.

Ryan Allen Castaneira was sentenced to 10 years in prison followed by 20 years probation and a $36,000 fine by Superior Court Judge Christopher Edwards. Castaneira also will have to register as a sex offender upon his release from prison.

Castaneira insisted in court this week that he thought she was “role playing” during the instant messaging sessions online with the undercover officer, who informed him she was 15 years old and living in Peachtree City.

Castaneira, 30, was arrested Sept. 20, 2006 after he traveled to the Kedron Village shopping center to meet up with the undercover officer.

Explicit Internet chat records between Castaneira and the officer were read in court this week. In one exchange, Castaneira informed the girl of special precautions that must be taken because it would be “her first time” having sex. He also admitted that he was the one who first suggested they meet in person.

Castaneira admitted in court that he sent the officer a photo of a naked man during one of their instant messaging sessions online. He also suggested that he had confused the officer’s undercover profile with that of another online individual using a similar name.

During part of the online chat, the two talked about meeting in a park area. Castaneira then told the officer to make sure the park was a place where they wouldn’t draw police attention.

District Attorney Warren Sellers also asked Castaneira that if he and the officer were “role playing” what role was Castaneira, presuming the officer was an adult pretending to be 15.

“I assumed she was playing the school girl role,” Castaneira said. “I didn't really know what my role was at the time.”

Castaneira also admitted that he came to visit Peachtree City from his Buckhead home the day before he was to meet up with the undercover officer.

Castaneira testified that he and his wife used Internet sites to meet other couples for swinging and they also placed ads on Craigslist to meet other swingers who shared the same interests as they do. Those people would respond by chatting with him via instant messaging services, he said.

Castaneira testified that he “assumed” the undercover officer was part of a couple, though there was nothing in the chat sessions nor the undercover officer’s online profile to suggest that she was a couple.

Castaneira told the jury that at some times he was chatting with so many different people at once he might have been mistaken when he chatted with the officer.