With each new sex case, the obvious question arises: Why do these predators choose Asia to commit their crimes?
Most experts in human trafficking say the region remains popular with sexual predators because of its corrupt law enforcement systems in some countries, pockets of endemic poverty and communities of like-mind criminals who can provide them with a safe haven.
"Everything here makes the crime easy," said Rosalind Prober, president of the Canadian children rights organization Beyond Borders, who is visiting Bangkok.
"This can be an open crime in Thailand when Western men are obviously in front of people carrying on in this way. It becomes normalized so they don't think they are doing anything wrong," Prober said.
Interpol has focused their worldwide manhunt for the 32-year-old Neil on Thailand, after he was caught on tape arriving at Bangkok's international airport Thursday from South Korea.
The photo, released by Interpol, shows a man with a cleanly shaved head and eyeglasses dressed in a white button-down shirt. Authorities believe it is the same man whose digitally blurred image appeared in about 200 Internet photos that showed him sexually abusing Vietnamese and Cambodian boys as young as 6.
Across Asia, hundreds of thousands of girls and boys are believed to work in the sex trade mostly in Cambodia, Indonesia, Thailand, Vietnam, the Philippines.
Some of their customers - mostly older men - commit their crimes with relative impunity, walking hand-in-hand with underage girls in Bangkok or with boys in a resort hotel on the Indonesian island of Bali. The victims in many cases are the poorest children, including beggars, street children and the homeless.
"It's all a manifestation of poverty that creates the vulnerabilities," said Richard Bridle, UNICEF's deputy regional director for East Asia and the Pacific.
In one Internet exchange intercepted by Cambodian police, two unidentified teachers talk about how easy it was for them to pickup mostly homeless boys between 10 and 14 and bring them back to their apartments for sex.
"I am having a wonderful time with them sexually. Some of them are very interesting. There is never a dull moment," one of the teachers wrote, according to a transcript published in 2004 by Beyond Borders. "Last night, four boys spent the night and I like all four of them."
Other pedophiles operate more covertly, depending on secretive pedophile rings in cyberspace to find their victims. The networks offer tips on the best places to meet children or arrange sexual rendezvous in luxury condos or on private yachts.
To get access to such networks and earn credibility among their fellow pedophiles, they often must provide evidence of sex acts they have committed with children - as Neil appears to have done by putting the sexually explicit photos of himself with young boys.
Still others turn to jobs like teaching or tutoring that gives them ready access to youngsters. Teaching English is especially popular because jobs are easy to get and the position carries with it a level of authority that makes it difficult for the children and even their parents to question abuses.
"The children are sitting ducks. This is their teacher. This is someone you trust and tells you what to do," Prober said. "You very quickly get trapped. There is such a level of control and power by a teacher. It's multiplied when it comes to a foreign teacher."
Pedophiles also take advantage of Asian legal systems where cash bribes can lead to charges being dropped or victim's relatives and other witnesses suddenly changing their stories.
Disgraced British rocker Gary Glitter received a three-year jail sentenced last year for molesting two Vietnamese girls, which was nine years short of the maximum. Before the trial, he gave US$2,000 (EUR1,550) each to the families of two girls, aged 11 and 12.
Asian governments, however, have begun to address the problem, enacting tough laws and moving to convict pedophiles in Cambodia, Thailand and Indonesia. Thailand, for example, has toughened its screening process for teachers since the Karr case.
Karr, who was arrested last year in Bangkok, confessed to killing 6-year-old JonBenet Ramsey. He was flown back to the United States to face murder charges, only to be freed when DNA tests failed to place him at the crime scene.
"It is very good now that we have the police help us screen teachers to make sure there is no previous (criminal) record," said Poramit Srikureja, an assistant chairman of a Christian school in Bangkok where Neil taught from August 2003 to January 2004. "It is a lot more difficult now to get teachers."
The Neil case, experts said, also shows that law enforcement agencies are better coordinating their enforcement activities and giving priority to pedophilia cases.
"We are beginning to see a trend going toward better laws, better policing and more awareness within public that this isn't acceptable," Bridle said. "I see this particular case as a great cause of optimism and great cause for redoubling efforts to both catch these people committing these crimes but also looking at vulnerabilities that underlie why children become victims."