The mother of Tim McLean -- the man who was brutally murdered then beheaded on a Greyhound bus in 2008 -- is welcoming proposed changes to the way the Canadian justice system deals with the mentally ill.

Carol de Delley said she expects the changes to be a step in the right direction, more than four years after Vince Li killed her 22-year-old son on a bus ride between Winnipeg and Edmonton in July 2008. Li was found not criminally responsible for the attack after he was diagnosed with schizophrenia.

On Thursday, the Conservative government announced plans to make it more difficult for mentally ill offenders who are found not criminally responsible to be released from custody. Justice Minister Rob Nicholson said he will introduce a new bill early next year that would make public safety the central factor when determining when to release an offender, but did not give specific details.

Under current laws, those deemed to be not criminally responsible for murder, such as Li, face a mandatory annual review that assesses whether they are eligible for day passes or day parole.

De Delley has attended every annual review since her son was killed, and feels the reviews should be held less frequently.

"At least if they were doing a review every three years that would guarantee or ensure the offender remains receiving treatment for three years instead of one year," she told CTV’s Canada AM. "There is currently no minimum period of detention that comes along with a not criminally responsible ruling, so three years is good.

"It's also a good thing for the family not to have to revisit it on an annual basis," she added.

De Delley said she feels an obligation to attend Li's review hearings, in order to remind the board members about the lasting impact of her son's murder -- and to show that she is paying attention to their decisions.

"I'm there to protest. I'm there to show, no, I don't want this individual out," she said.

Making the announcement in Montreal Thursday, Nicholson said the government is concerned about the rights of victims of crime, and their families.

"Our government is listening to victims, as well as the provinces and territories, who are telling us that the safety of the public should be the paramount consideration in the decision-making process involving mentally disordered accused persons," he said in a statement.

The justice system exempts individuals from criminal responsibility if, at the time they committed an offence, they were suffering from a mental illness and didn't understand the consequences of their actions. Those found not criminally responsible are typically detained in mental-health institutions as opposed to prisons.

In many cases, within a few years of the offence, the accused is permitted day passes to leave the institution and spend time in the community. In some cases, it may be the same community where victims’ families still live.

But some mental-health advocates disagree with decreasing the frequency of the annual reviews.

Dr. Philip Klassen, vice-president of medical affairs at Ontario Shores Mental Health, said he would actually like to see more-frequent reviews of the mental health of the not criminally responsible.

He said by law, NCRs must go through a review "not less frequently than annually," but said issues related to risk and rehabilitation often change at a fast pace. The boards simply can't keep up if they are only assessing someone once a year.

Medication, mood and environmental issues all play a role in how a patient behaves on a given day, he said.

"We default to the least-frequent reviews when sometimes more-frequent reviews would be actually of benefit," Klassen told Canada AM.

He said it's important to remember that people deemed not criminally responsible have suffered from a mental illness -- and often do so for years. "If reviews are less frequent, it means there's disengagement, if you will, by the accountable body from what's happening with that accused," Klassen said.

Forensic psychiatrist Ag Ahmed, of the Royal Ottawa Health Care Group, told CTV News Channel Thursday that he hopes whatever changes proposed by the Tories takes into account the need to rehabilitate and reintegrate those with mental illness into society.

“It’s not just medication, it’s a psycho-social intervention,” said Ahmed. “You want to send the patient into the community, you want them to attend other programs. Should there be a restriction, it would make it very difficult to get this individual reintegrated into the community.”

Ahmed also pointed out that keeping those with metal illnesses detained for longer periods of time would strain the already limited resources available to these individuals.