(CNN) -- A man charged in the beheading death of his seatmate on a Greyhound Canada bus last summer is not criminally responsible because he is mentally ill, a judge ruled Thursday, said CNN affiliate CBC News.
The ruling means that Vince Weiguang Li will be hospitalized at a psychiatric facility until he undergoes a review by Manitoba's Criminal Code Review Board in 90 days, CBC said.
"The goal of criminal law is to punish criminals, not persons who have a severe mental illness," Manitoba Court of Queen's Bench Judge John Scurfield wrote in the ruling, CBC reported.
However, the ruling angered relatives of Tim McLean Jr., 22, who died on the bus July 30.
"The bottom line is, he is getting away with murder," Vana Smart, McLean's sister, told CBC. Watch how the verdict angers the victim's family »
Prosecutors told reporters Thursday they had no choice but to ask the judge to find Li not criminally responsible.
"This was justice because the correct conclusion was reached," prosecutor Joyce Dalmyn said, according to CBC. "Mr. Li is a schizophrenic. Mr. Li had a severe mental disease. Mr. Li, in my opinion and in the opinion of the psychiatrists, had no idea what he was doing was wrong."
Li, 40, was charged with second-degree murder in McLean's death. A witness on the bus, which was headed from Edmonton, Alberta, to Winnipeg, Manitoba, said a passenger repeatedly stabbed and then decapitated McLean as horrified passengers watched. Just before his death, the victim had been sleeping with his head leaning against the window.
"There was a blood-curdling scream. I was just reading my book and all of a sudden I heard it," Garnet Caton, who was sitting in front of the two men, told Canadian TV at the time. She said the knife-wielding man shouted at the other passengers to get off the bus, and they did.
"Me and a trucker that stopped and the Greyhound driver ran up to the door to maybe see if the guy was still alive or we could help or something like that," Caton said. "And when we all got up (to the door), we saw that the guy was cutting off the guy's head."
Thirty-four passengers were on the bus. Police said at the time it was unclear what prompted the attack. Witnesses said Li's weapon was a large butcher knife.
Li was arrested after an hours-long standoff, during which he remained in the bus with McLean's body. Police said he was seized after he broke a window and attempted to jump from the bus.
"Mr. Li is also a victim here," said Ruth Ann Craig of the Canadian Mental Health Association, according to CBC. "What's going to happen to Mr. Li is not a cakewalk."
He will be housed in a locked psychiatric ward, Craig said, while he undergoes assessment and treatment to determine whether he is a risk to himself or society.
But Tim McLean's mother, Carol deDelley, said she will fight to change the law regarding these types of crimes. "I'm going to do everything I can to make a change here," she said, CBC reported.
McLean's father said he is also disappointed with the ruling.
"We've all lost a family member," he told CBC. "This isn't the right result."