A man found not criminally responsible in a 2014 stabbing death left Canada on an international flight earlier this month while on an unaccompanied community pass, the Centre for Addiction and Mental Health (CAMH) in Toronto confirmed Wednesday.

Zhebin Cong, 47, was charged with second-degree murder in the death of San Tai Yuan at a rooming house in suburban Toronto in North York. Two years later, he was found not criminally responsible because of a mental disorder.

On July 3, he got on an international flight, say Toronto police, who wouldn't disclose where he went.

In an afternoon statement, CAMH said Cong had been on an unaccompanied pass to the community — in accordance with the terms of his Ontario Review Board disposition — on the day he went missing. When he didn't return, CAMH said, it notified police at 6:50 p.m. ET.

"CAMH takes this incident very seriously," the centre said, adding it has launched an internal review into this "specific and rare incident."

As recently as April, Cong was found to pose a "significant threat to the safety of the public," according to the review board documents.

The documents say Cong has schizophrenia and was living in a general forensic unit at CAMH.

CAMH said it's taking immediate action as additional precautions following Cong's disappearance, including:

Having the physician in chief oversee a reassessment process for all existing passes and privileges where patients have unsupervised access to the community.

Adding clinical staff and security staff at all its forensic units.

"Privileges such as community passes are only granted if several conditions are met, including Ontario Review Board authorization," the CAMH statement added.

Mayor has 'many questions'

Toronto police said they were working with international law enforcement agencies to track down Cong, who records show is originally from China.

They said they investigated his disappearance for 11 days before deciding to ask for the public's help. Police did not identify him as a CAMH patient in the missing-person notice and cited privacy reasons for not doing so. They also noted that CAMH told them Cong presented a low risk to public safety.

An earlier police news release described Cong as someone who had difficulty speaking English, and said police were concerned for his safety.

Cong went missing from the intersection of Ossington Avenue and Queen Street West, where CAMH is located, hours before he fled the country, the release said.

Toronto Mayor John Tory said Wednesday morning in a statement that he has "many questions about how this could have happened."

He also wrote he's confident CAMH and authorities are working hard, and "will make any changes necessary to make sure this situation is never repeated."