An Aboriginal mother who died from “mixed drug toxicity” while in a Maitland police station cell might have survived had she been adequately assessed, an inquest has heard.

Acting state coroner Teresa O’Sullivan is investigating the circumstances surrounding the death of Rebecca Maher in July 2016 after she was detained by police – who wrongly believed she had HIV – for being intoxicated.

Counsel assisting the coroner David Buchanan told the court in Newcastle an autopsy had revealed toxic levels of methadone and benzodiazepines in the mother of four’s system leading to respiratory failure.

Mr Buchanan on Monday said medical evidence would be given that the Wiradjuri woman could have survived if she’d been adequately assessed by police and an ambulance called.