Authorities investigate a shooting in the suburb of Hoxton Park on Feb. 10, 2015, in Sydney. (Ben Rushton/Getty Images)

Courtney Topic stood on a busy street corner in southeastern Australia, sipping a soft drink and clutching an eight-inch kitchen knife.

Medical experts later speculated that the 22-year-old woman, who had been diagnosed with depression and Asperger's syndrome, may have also been suffering from schizophrenia, a serious mental illness characterized by a patient's inability to discern fantasy from reality, when she started swinging the blade and talking to herself in February 2015.

Cellphone video captured the moment when New South Wales police surrounded Topic outside a Hungry Jack's fast-food restaurant near Sydney. The young woman ran a short distance with the officers in pursuit.

The Sydney Morning Herald reported at the time that officers used pepper spray and tried unsuccessfully to employ a stun gun. Then, one of the officers opened fire, fatally shooting Topic in the chest, police said.

More than three years later, an inquest into Topic's death has been opened in the NSW Coroner's Court to determine what happened and whether lethal force was necessary. The case has drawn international attention, reigniting a debate about how law enforcement officers around the globe are trained to handle those with mental illness.

Topic's mother, Leesa Topic, said in court Monday that her daughter was a “beautiful, intelligent, sweet, quirky, creative, quick-witted” young woman who would be remembered as “a loving, caring, honest, genuine, gentle soul,” according to the Sydney Morning Herald.

“Her harrowing loss is palpable,” she added. “We must live with this pain forevermore.”

Precisely 41 seconds after police arrived on the scene Feb. 10, 2015, police said Senior Constable Ethan Tesoriero fired the fatal shot.

Tesoriero told the court last month that he had called out to Topic, “Drop the knife, ma’am,” and “I need you to drop the knife for me right now,” but she did not comply, according to BuzzFeed News.

Tesoriero said that another officer used pepper spray on the young woman and she then approached Tesoriero, and he believed that she was going to harm him, according to the news site.

“Every turn that I made, she made,” he told the court, according to BuzzFeed News. “I thought that she was going to stab me.”

Tesoriero told the court that, given the opportunity to do it over, he would not respond any differently, according to BuzzFeed News.

Topic's mother told reporters Monday that she was “deeply disappointed” to know that he would shoot and kill her daughter again.

“Clearly, situations like this are unpredictable and they are volatile, but we cannot accept that Courtney's death was unavoidable,” Leesa Topic said at a news conference outside the courtroom, according to 7 News Sydney. “We were deeply disappointed to hear the officer who fired the fatal shot tell this court that three years on, he would not do anything differently.”

“Mercifully, few parents will have to watch a child die at such a young age. Fewer still will have to watch a child die in such public circumstances, or be forced to grieve in the public eye as we have been. Yet despite the very public nature of Courtney's death, we were left with many unanswered questions,” the grieving mother added.

“We could not understand why the officers who arrived at the scene, crowded so quickly and so closely around a young woman who did not, in the moments before they arrived, pose an immediate threat to members of the public. We could not understand why officers, when encountering a person who was displaying signs of possible mental illness, would not take steps to diffuse the situation and would resort to lethal force so quickly.”

A 2013 report from the Australian Institute of Criminology showed that there were 105 fatal police shootings in the country from 1989 to 2011. Among those, 44 involved people with mental illness, including disorders such as schizophrenia, according to the data.

According to the report:

One issue that frequently arises with regard to police shootings is proportionality, or more simply, whether the threat or potential threat posed by the alleged offender was sufficient to warrant police using a firearm. This issue is tested through coronial inquests in which the presiding coroner will make a determination about whether the shooting was justified.

This issue becomes much harder to resolve when the mental capacity of the alleged offender is impaired, such as by drugs and/or alcohol, a mental illness or both, as the ability to understand or appreciate the consequences of potentially life-threatening actions may be undermined.

Topic's mother said she hopes police will “learn from tragedies” like her daughter's death so that they do not happen again and again.

“We want to see better recognition among police of mental illness,” Leesa Topic said. “Above all, we want to save other families the tremendous loss that we have experienced.”

Courtney Topic's mother breaks down at inquest

"We were deeply disappointed to hear the officer who fired the fatal shot tell this court that three years on he would not do anything differently." - Leesa Topic's daughter Courtney Topic was shot by officers in 2015 after a heated confrontation at Hoxton Park.Story: #7News

Posted by 7 News Sydney on Monday, April 16, 2018

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