These images made available by Interpol in Paris show an unidentified man after, left, and before the digital manipulation of the image.
An international manhunt for an alleged pedophile centered Tuesday on Thailand, where authorities said the suspect, 32-year-old Christopher Paul Neil of Canada, was believed to be at large.
Meanwhile, neighboring Southeast Asian nations placed their borders on the lookout for the man, whom authorities described as a teacher whose digitally blurred image had appeared in Internet photos showing sexual abuse of boys.
The Interpol agent in charge of the case, Mick Moran, said the suspect had taught in Thailand, Vietnam and South Korea and entered Thailand last week on a one-way, full-fare ticket from Seoul.
"Cambodia, Vietnam, Thailand — all the countries in this region have all been alerted — they're all on alert and they all have border controls in place in an effort to spot the movements of this man," said Moran, who arrived in Bangkok over the weekend to coordinate the manhunt. He appealed to the suspect to surrender "to have the matter sorted out in a reasonable and adult manner."
The international police organization had issued an unusual global appeal for help in identifying and tracing the suspect on Oct. 8.
Authorities said the man was shown in some 200 Internet photos abusing young boys in Vietnam and Cambodia. His face, however, was masked by a digitalized blur. German police managed to recreate an image of him, and four reconstructed photos were released to the public.
On Monday, after receiving hundreds of tips, Interpol announced it had identified the suspect. While Interpol did not make public the man's name, it said he was thought to be on the run in Thailand, where security cameras had documented his arrival Thursday. Thai and Cambodian police revealed the man's name, age and nationality Tuesday.
"We believe he is still in Thailand and we are now collecting information from neighboring countries where he committed crimes of pedophilia so we can issue an arrest warrant for him," Thai police Col. Apichart Suribunya told The Associated Press.
A Canadian Embassy spokesman declined to comment.
Investigators have been hunting the man in the photos for three years, since German police discovered online photographs of him abusing underage Asian boys. He was allegedly shown sexually abusing 12 young Vietnamese and Cambodian boys, apparently ranging in age from 6 to early teens.
Interpol said that more than 350 people supplied tips to authorities worldwide. Officials are still collecting and analyzing evidence to bring charges if the man is arrested, it said.
Cambodian police have "alerted all border checkpoints" to the man's identity, acting on a request from Interpol, said Keo Vanthan, a senior police official in charge of Cambodia's Interpol division. He said police were investigating whether the suspect had previously entered Cambodia.
The case marks the latest high-profile pedophile manhunt for Thailand.
John Mark Karr, who confessed to killing 6-year-old American beauty queen JonBenet Ramsey was arrested in Bangkok last year only to be freed for lack of evidence.
Like the current suspect, Karr worked as an English teacher in Bangkok and in South Korea, among other places.