Christopher Paul Neil, a 32-year-old schoolteacher who worked in several Asian countries, has pleaded not guilty in the case. He was arrested in Thailand on Oct. 19, 2007 after Interpol issued an unprecedented global appeal to help apprehend him.
Shackled and smiling, Neil waved to a friend and said, "How's it going?" as he entered Bangkok's criminal courthouse ahead of the trial. He was wearing an orange prison uniform, barefoot and chained to another prisoner.
"I hope there will be justice in Thailand," he told The Associated Press.
Neil is accused of sexually abusing a 9-year-old Thai boy, who contacted police after seeing Neil's face on television following his arrest. The child claims Neil paid him 500 baht ($15) to 1,000 baht ($30) to perform oral sex in 2003, while he was living in Thailand.
He faces up to 20 years in prison for charges that include sexually abusing a minor and videotaping the alleged abuse, taking a child without parental consent and holding him against his will.
"We've got the evidence and we have the victim," said prosecutor Sontus Singhapus. "He's guilty."
Prosecutors plan to introduce some 70 photographs that allegedly show Neil engaging in sexual acts and playing with young naked and partially clothed young boys, said Sontus.
They also plan to put the victim, now 14, on the stand along with his parents and another boy who recruited the youngster for Neil.
Sontus said Neil could face additional charges if police can track down other Thai victims whom he allegedly abused.
Neil's opening hearing was quickly adjourned after the court assigned him an attorney and set the next session for June 2.
Interpol's public call for help was based on the discovery of some 200 Internet photos believed to show Neil sexually abusing at least a dozen Vietnamese and Cambodian boys, some as young as 6.
The photos were found online in 2004, but the face of the perpetrator was digitally obscured as a swirling shape. After three years of searching, the international police agency was able to unscramble the images with the help of German police computer experts. Interpol circulated the pictures publicly and received hundreds of tips that led them to identify Neil as the suspect.
Neil was arrested 11 days after the appeal was launched after flying into Bangkok on a one-way ticket from South Korea, where he was working as an English teacher. He was caught at the house of his boyfriend, identified as Ohm, in Nakhon Ratchasima province in the country's northeast.
Ohm, who refused to provide his full name, was at the hearing Monday and insisted Neil was innocent.
"How can this be him?" Ohm said. "When I stayed with him, there was nothing like this. I don't believe (the charges)."
Neil had taught at various schools in South Korea, Thailand and Vietnam since 2000. Previously, Neil worked as a chaplain in Canada, counseling teens.
Neil lived in Thailand from 2002 to early 2004, according to police.
Since Neil's arrest, Interpol has said it will allow wider use of public appeals to track suspected pedophiles, trying to build on the success it had tracking down the Canadian.