Jayden Tanee Lowah, 25, was found not guilty by reason of mental incompetence in 2020 of the murder of Michelle Foster, 36, outside an Adelaide shopping centre in October 2018.
After the SA Supreme Court ordered that he serve a period of indefinite mental health supervision, Deputy State Coroner Naomi Kereru held an inquest to examine the circumstances of Ms Foster's death.
In findings released on Wednesday, Ms Kereru said it had been necessary to examine how and why Mr Lowah was in the community in a psychotic state and able to kill an innocent young woman, 41 days after his release from prison.
Mr Lowah was "a very unwell and dangerous individual from an early age", who was diagnosed with schizophrenia at age 15 after threatening to kill his father.
Ms Kereru noted that Ms Foster's mother, Andrea Foster, had "good reason for feeling hatred towards Mr Lowah, (but) she saw her daughter's death in a different light after hearing the evidence at inquest".
"Fundamentally as a system, we failed Jayden and the community," Ms Foster said.
"He was released when it was not safe to do so and he was not in a position where he could be safely reintegrated into the community."
After being convicted of two random attacks on strangers in August 2017, Mr Lowah was released from prison in September 2018.
The day before his release, a prison social worker wrote: "Prisoner Lowah is at high risk of reoffending and harming others due to his significant history of making threats towards others, poor frustration tolerance, impulsivity and emotional dysregulation."
At 2.15am on the day after his release, Mr Lowah called an ambulance and said he wanted to go to hospital because he felt as if "I'll probably kill someone".
"On its face, the decision to discharge Mr Lowah into the community from the ED, with a history of schizophrenia after having expressed an intention to hurt or kill someone, appeared fundamentally flawed, particularly in light of Ms Foster's violent death six weeks later," Ms Kereru found.
In finding Ms Foster's death was not preventable, she noted "lost opportunities for the trajectory of Mr Lowah's illness to have been altered".
The coroner said that throughout the inquest, there were comments from witnesses about the resourcing of the mental health system, including Chief Superintendent James Blandford.
"(During) 43 years of policing, taking people backwards and forwards … to Glenside (hospital) where they were actually given asylum and care, to now a public hospital or a GP, they are out before my people have finished the paperwork because there are … no facilities for people who are in crisis," he said.
Ms Kereru recommended the attorney-general consider broadening the definition of "high risk offender" for an extended supervision order, with an additional category for offenders identified as an unacceptable risk to the community.
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