An Aboriginal woman who died in a police cell in New South Wales would have survived if police had physically checked her and called an ambulance when they realised she was unconscious, an inquest has heard.

Rebecca Lyn Maher was found dead in cell four of the Maitland police station at 5.54am on 19 July 2016, about five hours after being taken into protective custody because she appeared intoxicated and had wandered into oncoming traffic at Cessnock in the Hunter Valley.

The 36-year-old Wiradjuri woman is the only Aboriginal or Torres Strait Islander person to die in a NSW police cell since the state introduced the mandatory custody notification service (CNS) in 2000.

She had been placed in the cell at 1.24am and ordered 10 minutes later to lie down, because she was sitting slumped on the mattress and looked likely to fall over.

A custody officer walked to the door of the cell seven times between then and discovering her death and looked at her through the perspex wall, but did not enter the cell or try to shake her awake, despite earlier noting problems with her breathing.

When the officer did enter her cell at 5.54am, Maher was unresponsive and surrounded by vomit. She was declared dead just over 10 minutes later after police and paramedics were unable to revive her.

In the opening statement at the inquest in Newcastle on Monday, David Buchanan, the counsel assisting coroner Tessa O’Sullivan, told the court the inquest would investigate whether the failure of police to follow procedures requiring them to attempt to wake an intoxicated person at least every 30 minutes had contributed to her death.

He said the inquest would hear from an emergency medicine expert, Dr John Vinen, who said in a report to the court that Maher “would have survived if paramedics had been called and she had been transported to hospital”.

Buchanan said police mistakenly believed Maher was positive to both HIV and hepatitis C and that this appeared to have contributed to a decision not to search her or handle her without gloves.

The inquest will also look at whether the failure to search contributed to her death, because two pill bottles containing 29 Alprazolam or Xanax tablets were found down her pant legs after she died.

Alprazolam is a benzodiazepine, a type of depressant drug that is often found in combination with opiates in fatal drug overdoses.

The autopsy showed Maher had fatal levels of Alprazolam and Mirtazapine in her system as well as high levels of methadone, the latter because she was a long-term participant on the methadone program.

The court heard the Alprazolam had been prescribed and purchased in Cessnock that day. Maher had travelled to the Hunter Valley town from Newcastle with her partner, who later told police they had taken the pills that evening.

Police said they originally intended to arrest Maher for breaching bail. When they learned her bail was not breached they decided instead to take her into protective custody under the Law Enforcement (Powers and Responsibilities) Act 2002 because she was “seriously intoxicated” and walking on to the road.

The Aboriginal Legal Service of NSW has previously criticised police for failing to contact the CNS when Maher was taken into custody. There is no legal obligation in NSW to contact the CNS unless a person has been charged with a crime.

Police said they did not know Maher was Aboriginal until after her death. Since Maher’s death the NSW police custody management system has been updated to flag if a person has previously identified as Aboriginal.

Maher was one of 17 people to die in police custody nationally in 2016-17, according to a recent report by the Australian Institute of Criminology, although that report does not record any Indigenous women dying in police custody. Six of the deaths occurred in NSW.

The inquest continues.