Alexander Bayne Centre walked 'difficult tightrope' on fatal trip

But deputy NSW coroner Erin Kennedy says this state's chief psychiatrist should review all policies and procedures used to grant extended leave to patients under involuntary care.

Their recommendation casts the spotlight onto the complex task psychiatrists perform as they try to help some of Victoria's most vulnerable people reintegrate back into the community during treatment in mental health facilities.

Darren Higgins' remains were found seven months after he went missing from a Mathoura caravan park bordering the Murray River in 2017.

He was taking three days' leave from Bendigo's Alexander Bayne Centre as part of a treatment plan to help ease him back into the community.

A psychiatrist at the facility - which is run by Bendigo Health - had signed off on the trip for the Yorta Yorta man, who would be cared for while away by his mother and highly respected Indigenous Elder.

Mr Higgins had complex mental health challenges. His schizophrenia was partially resistant to treatment, he was prone to volatile mood swings and could struggle with insights into his impulsive behaviour.

He had what one expert described as a "huge" drug misuse disorder.

But Mr Higgins was 12 months into an involuntary stint in care and was clearly struggling with being so far away from his family, community and culture.

He had been gradually spending more time under the supervision of his mother and on walks through the community.

His psychiatrist made their call to allow the Mathoura trip based on their years of experience and their specialist knowledge.

"It is a difficult tightrope to walk, to try and promote reintegration and freedom for Darren while mindful of his serious condition," Magistrate Kennedy said in her findings.

The psychiatrist felt risks of three days leave could be mitigated by Mr Higgins respect for his family and high opinion of the Indigenous Elder, along with medications that could ease some of his symptoms.

They were also swayed by the plan to avoid Echuca, a town where Mr Higgins could have been more likely to come into contact with people he knew could supply him drugs.

But Mr Higgins struggled during the trip.

He tried to leave, saying he wanted to see family members, prompting calls to specialists in Bendigo who made it clear he was not to leave his mother and Indigenous Elder's supervision.

By the evening of February 10, Mr Higgins had swam into the Murray River, making for the Victorian side and the Barmah Forest, part of the traditional lands of his people.

His mother and the Indigenous Elder called Triple Zero and spent the night searching for him along the river banks and along the route to Echuca.

What neither they nor police in both states knew that night was that Mr Higgins had swum back across the river half-an-hour after he had left the caravan park.

Magistrate Kennedy suggested Victorian policymakers could consider Mr Higgins' case if they were looking at ways patients were granted leave, to see if there were any particular points related to his case that could help someone else.

Mr Higgins was missing for nearly seven months before someone found his remains in NSW's Moira State Forest, in the Barham area.

He likely died within a day or two of going missing from complications from dehydration, Magistrate Kennedy said.

He had left the caravan park on a day when the mercury had risen past 40 degrees and did not take clean water or money with him.

Drinking dirty water from the Murray or nearby pools of water would probably have made him sick and fuelled his growing dehydration, Magistrate Kennedy said.

Magistrate Kennedy said the police response was hampered by officers on both sides of the river not being able to easily share information.

That was a problem both police forces should now tackle, even if fully solving it will be difficult given officers on either side of the Murray use different electronic systems, she said.

This is, after all, the era of emails and mobile phones, Magistrate Kennedy said.

"It would seem a pathway or protocol should be able to be created to at least promote easy police cross border conversation and communications between these very important border towns," she said.

The deputy coroner also recommended extra cultural training and more thought to how NSW police might better use aboriginal community liaison officers when First Nations people go missing.

Both NSW and Victoria's police forces have confirmed they are reviewing the deputy coroner's findings.

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