Health workers missed several red flags before a mentally unwell man was shot dead by police in Thames seven years ago, the coroner has found.
Vaughan William John Te Moananui, 33, was killed in May 2015 after advancing towards police officers holding a rifle.
In just-released findings, Coroner Michael Robb said Waikato District Health Board failed Te Moananui and his whānau.
While "it would have been next to impossible to predict the precise events that tragically unfolded", there were well-known risk factors which should have been picked up.
The "single greatest failure" was poor monitoring by Te Moaoanui's key worker from November 2014, he said.
Te Moaoanui, who had a long history of paranoid schizophrenia and alcohol-related offending, was supposed to have weekly contact after being released from hospital in mid-2014.
However, his key-worker had very little contact with him or his family after he moved into a flat by himself in December 2014 until his death five months later, apart from a single phone call with his mother in March 2015.
The nurse, who worked part-time, had a big case load plus responsibility for acute call-outs over a large geographical area.
The psychiatrist who oversaw his care was also criticised for relying on false assumptions that the patient was sober, stable and taking his medication.
This specialist, who had only arrived in the country two weeks before taking over responsibility for Te Moananui's care, failed to recognise the risks or note the paucity of the information before him.
Forensic psychiatrist Dr David Chaplow, who was an expert witness, criticised the lack of a safety net.
"The system of accountability was so lax that there was little hope of detecting early signs of deterioration in Mr Te Moananui's mental status before it reached the crisis that eventuated. It was clear that the whānau were concerned well before the tragedy occurred."
There was no risk management plan when he was released from hospital, nor was drug and alcohol counselling arranged.
The coroner has recommended all "high risk" individuals received effective monitoring to ensure the "circle of care" was actually working.
In its response to the coroner, Waikato District Health Board said one limiting factor was the lack of availability of people to do the work.
"They explained that the situation could not be fixed by money alone and certainly not with the level of funding potentially being made available."
Since 2015, the DHB had started working collaboratively with an iwi-based mental health provider and employed a nurse on the weekend for mental health callouts.
It had also changed its process to ensure all high-risk individuals were reviewed by a multi-disciplinary team every three months.
However, the coroner noted this would only be as effective as the information provided by the keyworker.
Te Moananui's whānau were concerned that police could have done more to avoid shooting him.
However, Robb said in his assessment, Te Moananui was so unwell at the time, the prospects of talking him down through negotiation or involving mental health were "very limited."
"As Vaughan advanced towards police officers with the rifle in those circumstances, I consider the police were left with no realistic prospect of safely controlling him and protecting others in the area."