A man who was found not criminally responsible for beheading and cannibalising a fellow passenger on a Canadian bus has been granted his freedom.

Manitoba's Criminal Code Review Board announced on Friday it had given Will Baker, formerly known as Vince Li, an absolute discharge, meaning he is longer subject to monitoring.

Baker, a diagnosed schizophrenic, killed 22-year-old Tim McLean in 2008. A year later he was found not criminally responsible due to mental illness.

Mr McLean's mother, Carol de Delley, has been outspoken against granting Baker freedom, saying there would be no way to ensure he continued to take his medication.

She declined comment in a post on Facebook, saying, "I have no words".

Baker was initially kept in a secure wing of a psychiatric hospital but was given more freedom every year.

He has been living on his own in a Winnipeg apartment since November, but was still subject to monitoring to ensure he took his medication.

In a written decision, the review board said it "is of the opinion that the weight of evidence does not substantiate that Mr Baker poses a significant threat to the safety of the public".

Baker's doctor, Jeffrey Waldman, told the board earlier this week that he is confident Baker will remain on his medication and will continue to work with his treatment team if released.

Baker 'no longer a violent person'

Baker sat next to the Mr McLean on the Canadian Greyhound bus after the young man smiled at him and asked how he was doing.

Baker said he heard the voice of God telling him to kill the young carnival worker or "die immediately".

He repeatedly stabbed Mr McLean while the young man fought for his life.

As passengers fled the bus, Baker continued stabbing and mutilating the body before he was arrested.

He severed Mr McLean's head, displaying it to some of the passengers outside the bus, witnesses said.

Chris Summerville, executive director of the Manitoba Schizophrenia Society, worked with Baker over the years and said he was "no longer a violent person".

"He absolutely understands that he has to (take his medication) and has a desire to live a responsible, moral life and never succumb to psychotic episodes and not to hurt anybody ever again," Mr Summerville said.

The Supreme Court of Canada ruled in 1999 that a review board must order an absolute discharge if a person does not pose a significant threat to public safety.

The ruling added there must be clear evidence of a significant risk to the public for the review board to continue imposing conditions after a person is found not criminally responsible.

Opposition Conservative member of Parliament James Bezan criticised Baker's release. He said earlier in the week it would be an insult to Ms de Delley and McLean's other relatives.

AP