An autopsy has been unable to determine the cause of an Aboriginal mother’s death in custody more than a week after she was discovered unresponsive inside a Northern Territory police watch house.

Police said the 44-year-old died from a suspected medical episode after being taken into custody in Tennant Creek on Christmas Day, with a forensic pathologist due to conduct a post-mortem on Friday.

In a statement on Monday, an NT Police spokesperson said the pathologist had listed the woman’s cause of death as “undetermined” and would now conduct further “toxicology” testing.

“While further testing is required to determine a formal cause of death, the current information suggests that the woman suffered a medical event alone in her cell,” Assistant Commissioner Peter Malley said.

A middle-aged man in a dark police uniform stands behind a lectern.

Peter Malley says he has “full confidence in the independent processes that already govern how police investigate death in custody matters”. (ABC News: Pete Garnish)

The ABC is not using the woman’s name while police continue to inform relatives about her death.

Police have previously said the long-term Tennant Creek resident was arrested for aggravated assault and spent almost two days in the watch house before her death on December 27.

During a press conference the following day Assistant Commissioner Malley said CCTV footage showed the woman falling to the ground at 12:34pm, shortly after a routine cell check, and she was found unresponsive at the next cell check at 1:03pm.

Multiple sources have told the ABC the woman suffered from rheumatic heart disease — a potentially deadly condition caused by repeated streptococcal infections.

Posies of flowers attached to a metal gate with a sign that says "Police only".

Loved ones have left floral tributes to the 44-year-old mother outside the police station. (ABC News: Marcus Kennedy)

Assistant Commissioner Malley said the woman had no visible injuries and no disclosures were made about underlying health conditions during an assessment as she was admitted to the watch house.

He said the woman’s medical history and procedures for care at the watch house would form part of a brief of evidence being prepared for the coroner, with an inquest mandatory for any death in custody under NT law.

Unlike the watch houses in Darwin and Alice Springs, no nursing staff work at the Tennant Creek watch house to gather health information.

Theresa Roe

Theresa Roe says there are many reasons why people may not disclose health information when taken into custody. (ABC News: Marcus Kennedy)

North Australian Aboriginal Justice Agency (NAAJA) chairperson Theresa Roe said relying on police to gather that information after making an arrest instead was “doomed to failure”.

She said there were a number of reasons people may not disclose health information when they are taken into custody, including language barriers, sensitivities around disclosing personal details and mistrust of police.

“NAAJA regularly receives complaints about inadequate medical care in police watch houses, with clients denied access to the custody nurse for lengthy periods, medical issues going untreated or being denied (or unable to access) medication,” Ms Roe said.

“As this case demonstrates, it is crucial to have an independent, health trained person speak with every individual taken into custody.”

Town searches for answers over mother’s death in custody

A remote outback town is searching for answers about why a “respectful, friendly and bubbly” Aboriginal mother died in the police watch house.

NAAJA has called for the woman’s death to be investigated independently from police, echoing similar calls made by the family of 24-year-old Warlpiri man Kumanjayi White, who also died in police custody last year.

Assistant Commissioner Malley said he had “full confidence” in the detectives working on the case.

“And I have full confidence in the independent processes that already govern how police investigate death in custody matters,” he said.

“I extend my condolences to her family and friends who are going through an incredibly difficult time.

“I would also like to thank the Tennant Creek community for their ongoing assistance.”

Police confirmed on Monday the crime scene at the watch house had been closed while the investigation remained ongoing.