A former Mountie turned crusader for vulnerable children wants those who have sexually abused kids to have their Canadian passports revoked to prevent them from travelling the world in search of their next victim.

Brian McConaghy was a forensic scientist with the RCMP who helped investigate Christopher Neil and Donald Bakker, a pair of notorious predators from British Columbia who travelled to Southeast Asia to abuse children as young as seven years old.

“I had never seen child rape videos before,” he said. “That was a life-changing experience for me.”

McConaghy later gave up police work and founded Ratanak International, a charity that helps children in Cambodia.

“I think one of the things that first world countries have to do is protect those vulnerable overseas in their countries,” he told CTV News.

Earlier this week, the United States announced it will start revoking the passports of registered child sex offenders and force them to apply for new ones that identify them as predators.

“The U.S. system, what they've just done is stamp a passport making it very clear (that someone is) a sexual predator when they go through immigration,” he said. “Many foreign countries will look at that stamp and say, ‘Get back on the aircraft. You're not coming in.’”

McConaghy says Canada should take it a step further, focusing on child sex tourists to prevent people like Neil and Bakker from reoffending.

“Anyone who has demonstrated they actually have used a Canadian passport to assault children overseas should not be allowed to have a passport again, period,” he said.

Immigration Canada says it can revoke a passport “if there are reasonable grounds to believe such action is necessary to prevent sexual offences against a child in Canada or abroad.”

McConaghy says anyone convicted of abusing kids overseas should automatically lose their freedom to travel and that the change should be made soon.

Neil and Bakker are now both out of prison.

“He’s already travelling internationally,” McConaghy said. “Thank you for that, Canada.”

With files from CTV Vancouver’s Shannon Paterson