A Canadian who spent more than three years in a Thai prison for sex crimes against children will likely be back on the streets of the Lower Mainland by Monday night, according to experts.

Christopher Neil was arrested at Vancouver International Airport on Friday night and has been in police custody in Richmond ever since.

He is awaiting a court appearance Monday.

Police took the rare step of arresting Neil on the grounds he allegedly could pose a danger to the public in Canada.

But a criminologist from Simon Fraser University said he probably won’t be held by Canadian authorities for long.

“There really isn’t any power to hold him for an extended period of time,” said David MacAlister, adding Neil will probably have conditions placed on his release.

“If he does that voluntarily he should be released the same day.”

If Neil refuses to sign the release, MacAlister said he could be held by authorities for up to a year.

Neil was the subject of a massive international manhunt for sexually assaulting children and posting the acts on the Internet, with his face disguised with a digital swirl.

He was arrested in Nakhon Ratchasima in 2007, about 250 kilometres from Bangkok.

Criminal attorney Jonathan Rosenthal told News Channel that he commends the quick actions of police.

“He pleaded guilty to abusing children sexually,” said Rosenthal, spokesperson for Beyond Boarders, an organization that helps young victims of sexual abuse and exploitation.

“Pedophilia is a disease. I doubt he received any treatment in Thailand for these egregious offenses,” said Rosenthal.

Neil will not be charged by Canadian authorities for the crimes he was convicted of in Thailand.

The RCMP said those charges have already been settled.

With a report from CTV British Columbia's Scott Roberts