A Victorian coroner has referred the 2017 death of Yorta Yorta woman Tanya Day in police custody to prosecutors for further investigation.

Key points: Coroner Caitlin English found Ms Day's death was "clearly preventable" and there was a possibility an indictable offence had occurred

Coroner Caitlin English found Ms Day's death was "clearly preventable" and there was a possibility an indictable offence had occurred She said the police had not conducted adequate checks on her

She said the police had not conducted adequate checks on her She also found "unconscious bias" was a factor when a V/Line conductor reported Ms Day to police

On the "totality" of evidence from the coronial inquiry, coroner Caitlin English on Thursday said there was the possibility an indictable offence had occurred.

"Ms Day's death was clearly preventable had she not been arrested and taken into custody," Ms English said, while delivering her findings.

On December 5, 2017, Ms Day had fallen asleep while travelling by train from Bendigo to Melbourne when she was taken off the train by V/Line officials at Castlemaine and handed over to police who put her in the local station's cells to sober up.

At the request of Ms Day's family during the three-week inquest in August last year, the coroner released CCTV footage from the cell Ms Day was held in.

Space to play or pause, M to mute, left and right arrows to seek, up and down arrows for volume. Watch Duration: 4 minutes 11 seconds 4 m 11 s WARNING: DISTRESSING CONTENT TANYA DAY HITTING HER HEAD IN CUSTODY

It showed her hitting her head at least five times inside the holding cell.

She was eventually taken to Bendigo Hospital, and later to St Vincent's hospital in Melbourne, where she died 17 days later.

Was systemic racism to blame?

Ms Day's family has pushed for a criminal investigation into the events that day, arguing racism was a factor.

At the beginning of the inquest in August, the family's lawyer argued Ms Day's catastrophic injuries had been caused by neglect.

On the last day of the inquest, Tanya Day's family said their lives would never be the same. ( ABC News: Nicole Asher )

As a result, the inquest became the first time special consideration was given to whether systematic racism was a factor in the way she was treated by authorities, and ultimately her death.

Ms English on Thursday said she found evidence from V/Line conductor Shaun Irvine that he did not notice Ms Day's Aboriginal heritage "unconvincing", noting his statement to the inquest made reference to it and also that he mentioned it to police on the day.

She found Mr Irvine had been affected by "unconscious bias" when he decided to call police.

"He was equivocal in his evidence whether he knew she was Aboriginal," Ms English wrote in her 111-page ruling.

Mr Irvine had referred to Ms Day as being "unruly" in his reports to his V/Line supervisor and to police.

"I find the decision to define her as unruly and to call for police rather than pursue other options has been influenced by her Aboriginality," Ms English said.

On-duty police did not conduct adequate checks, says coroner

Coroner English also said the quality of the cell checks on Ms Day during the four hours she was in custody "did not meet" Victoria Police Manual guidelines, which require a person in these circumstances to be physically roused and actively engaged every 20 minutes.

The police check at 4:50pm was "completely inadequate", Ms English said.

Ms Day knocked her head a last time at 4:51pm — according to the CCTV footage — falling to the floor.

During the next check at 5:35pm "the door flap should have been opened" she said.

"Ms Day was vulnerable in custody owing to her Aboriginal heritage," Ms English said.

Ms English questioned the evidence of Leading Senior Constable Danny Wolters, where CCTV footage from the cell contradicted his claims that in his check on her at 5:56pm she was "moving around freely".

She noted there was a 68-minute gap between the second and third checks of Ms Day, and 81 minutes from the last check to when police opened the cell door after 8:00pm.

She told the court Senior Constable Wolters was not a "credible witness".

Apryl and Tanya Day. ( Supplied )

The coroner found Sergeant Edwina Neale and Senior Constable Wolters — who were attending to Ms Day in the cells — showed "cultural complacency" in dealing with people who were intoxicated, using a "minimalised approach to her medical needs".

They did not take proper care of Ms Day, Ms English said in her findings.

Ms English recommended that custody risk assessments include assessing the risk of falls because of alcohol, drugs or illness.

'Opportunity lost' for Ms Day to survive after falling

If "proper physical checks had been done every 30 minutes" she would have been checked 10 minutes after the fall in the cell at 4:51pm, Ms English said.

Ms English said "there was an opportunity lost for her survival".

Ms Day's family did not attend the findings hearing because of restrictions at the Coroners Court of Victoria to deal with the coronavirus outbreak.

Before the inquest began the Victorian Government said it would drop the state's public drunkenness laws, but the changes have not yet been made.

Ms English also noted that police who responded to the V/Line call at Castlemaine station did not deal with her medical situation adequately.

The officers said Ms Day was saying "meaningless and unintelligible things" on the train, which Ms English said warranted a "coma scale three response" which would have meant taking Ms Day to hospital or otherwise seeking emergency medical treatment.

"There was minimal compliance of the medical checklist," she noted.

The officers said Ms Day's condition had improved once she was off the train, and they decided she did not need medical attention, the court heard.

Officers did seek to find her family to take her home, the court was told, calling her daughter who was not able to pick her up at that time.

The court heard officers instead opted to detain her and take her to the local cells for her own safety, saying they were worried what would happen to her when she alighted in Melbourne.

'Sparks of justice' for family

Tanya Day's daughter Belinda argued systemic racism played a role in her mother's death. ( Supplied )

Ms Day's family said it had been a "gruelling and traumatic process" but the coroner's decision to request a criminal investigation into the death was the first step towards justice.

Ms Day's children Belinda, Apryl and Warren said they were happy with the overall outcome.

But daughter Apryl Day said the family was disappointed "the coroner stopped short of finding that Victoria Police were influenced by systemic racism".

"We know that our mum would have been treated differently and still be alive today, if she was a non-Indigenous woman," she said.

Belinda Day said it was a historic day for Aboriginal people but "bittersweet" for the family.

"This isn't the end of the road but is just the beginning of justice for our mum," she said.

"While there are sparks of justice in today's decision, for as long as Aboriginal people are targeted by police … the fight for true and complete justice for our people will be ongoing," Warren Day said.

Police to review findings

Ms English made a number of recommendations to the Attorney-General, Victoria's Police Chief Commissioner, the V/Line chief executive and the secretary of the Department of Justice.

The recommendations for the police included reviews of training and education and for guidelines to be amended to include a falls risk assessment for detainees suspected to be affected by alcohol, drugs or illness.

Victoria Police said it would now take time to review the findings and recommendations.

In a statement, police said the force took any death in police care or custody "very seriously" and acknowledged the suffering and loss of Ms Day's family.

"All coronial findings provide an opportunity for Victoria Police to review its policies and practices to ensure the safe management of people in police care or custody," the statement said.

One of Ms English's recommendations for V/Line was to provide training for its staff about unconscious bias and to include input from the Aboriginal and Torres Strait Islander community in its training materials.

A V/Line spokesman said the top priority always remained the safety of passengers and staff, and the organisation would give the coroner's recommendations "the serious consideration they deserve before commenting further".