Mr Li repeatedly stabbed Mr McLean before decapitating him
A man who beheaded a fellow bus passenger is not criminally responsible due to mental illness, a Canadian judge has ruled.
Justice John Scurfield said Chinese immigrant Vince Li should not be held accountable for the killing last July.
The decision means Mr Li, 41, will be treated in a mental institution instead of going to prison.
The victim's family dismissed the trial as a "rubber stamp" that allows Mr Li to get away with murder.
Carol deDelley, mother of victim Tim McLean, said her son did not die in vain and that his death would highlight concerns about the justice system.
The judge called the attack "grotesque" and "barbaric" but "strongly suggestive of a mental disorder".
"He did not appreciate the actions he committed were morally wrong. He believed he was acting in self-defence," he said.
Mr Li admitted killing Mr McLean, 22, but pleaded not guilty to second-degree murder in the attack.
The prosecution and defence agreed that Mr Li, 41, is schizophrenic. The court heard that Mr Li had claimed that God had instructed him to kill Mr McLean.
The trial lasted less than two days and heard from just two witnesses, both psychiatrists, who testified Mr Li is mentally ill.
Dr Jonathan Rootenberg, for the defence, said Mr Li claimed to hear the voice of God telling him to kill Mr Mclean or risk being killed himself.
"The voice said: 'Do it now... If you don't, he's going to kill you'."
Mr Li tried to flee the bus through a window
Dr Stanley Yaren, for the prosecution, said Mr Li was undergoing a major psychotic episode, including auditory hallucinations.
Furthermore, Mr Li believed his victim had supernatural powers and would come back to life if he did not cut him apart and spread his body parts around, Dr Yaren said.
The attack on 30 July last year took place in front of terrified passengers as the inter-city Greyhound bus travelled through Canada's vast prairies.
The court heard the details of the attack in a statement of fact agreed to by the prosecution and defence.
Mr Li, a former church custodian and computer programmer who emigrated to Canada in 2001, stabbed Mr McLean, who was sitting next to him, 50 or 60 times before cutting off his head and removing internal organs.
The attack began without warning. Alerted by screams from the victim, the driver stopped the bus and fled with the passengers as Mr Li continued his attack.
Police documents said Mr Li appeared to "smell, and then eat parts of Tim McLean's flesh" as they surrounded him in the bus 90km (55 miles) west of Winnipeg.
Body parts were found in plastic bags throughout the bus and the victim's nose and tongue and one of his ears were found in Mr Li's pocket, police said.
Mr Li, who had been locked in the bus, was apprehended as he tried to leave by a window.
He was later heard in a pre-trial hearing to plead "please kill me".
Mr McLean's family want to change the law that allows people who are found not criminally responsible to be released into the community once they are deemed well without serving a minimum sentence in jail.