WINNIPEG - The Manitoba review board that decided the fate of a man who beheaded a sleeping passenger on a Greyhound bus released the reasons for its decision Thursday, calling Vince Li a "significant risk" to the public.

Li was found not criminally responsible for killing Tim McLean last summer in front of horrified passengers near Portage la Prairie, Man.

A judge ruled in March that Li suffered from untreated schizophrenia and did not realize that killing the 22-year-old carnival worker was wrong.

Li's case was then handed over to the province's review board to decide if he should be given an unconditional discharge, released with conditions or continue to be kept in a mental health facility.

The board ruled in June that Li must remain in a locked ward of a mental health facility until his case is reviewed again next year.

"We are of the opinion that without the continued, close supervision provided by detention in hospital, Mr. Li would be a significant risk to the safety of the public, and that neither an absolute discharge nor a discharge upon conditions would be appropriate," the board said in its reasons for its decision Thursday.

The board initially said it might not release the reasons for its decision out of concern for Li's privacy rights. Following an outcry from McLean's family and others, the board decided to make its detailed decision public.

Li's mental state was central to the decision, the board said.

"It is clear that Mr. Li suffers from schizophrenia and continues to show some of the negative symptoms of the disease," the board said.

"The active psychotic symptoms have pretty well dissipated over the approximately 12 weeks that he has spent in hospital."

The board noted that Li's schizophrenia causes a "propensity for dangerous behaviour" and that he has shown a lack of insight into his illness. It also says Li has a history of refusing treatment for his illness and has shown "unpredictable, threatening, impulsive and anti-social behaviour."

The board followed the recommendations of Li's treating psychiatrist who testified that the man has made a lot of progress in care.

Psychiatrist Stanley Yaren said Li is no longer bedevilled by voices in his head but still needs to be locked up under the "highest level of security possible."

The review board is to reassess Li's case next year to determine if he is eligible for release or more lenient conditions. Until then he is to remain confined to a locked ward at the Selkirk Mental Health Centre. If he has to leave the ward or the hospital, he has to be escorted by two staff members or peace officers.