The family of an Aboriginal woman who died last year in police custody in Western Australia are demanding an urgent inquest into the 22-year-old's death.

Ms Dhu died in South Hedland in the Pilbara and her family said they had no idea what caused her death.

Two other West Australian families are also desperate for inquests, two years after their family members died in custody.

Ms Dhu's grandmother Carol Roe can see her granddaughter's grave from her backyard but said she had no idea why her "baby" died.

"It's very upsetting," Ms Roe said.

"My granddaughter, she should be sitting at this table with me. It's heartbreaking, no truth, no justice, no inquiries."

The WA coroner has received the relevant police and health department reports into Ms Dhu's death. A decision on an inquest date is now in the coroner's hands.

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Ms Dhu was locked up for unpaid fines and died in August 2014 while in the custody of the South Hedland Police.

She had been taken to hospital twice while in custody but discharged both times and returned to her cell after being issued with a medical certificate.

But on her third visit to the Hedland Health Campus Ms Dhu died.

"Six months since I lost my granddaughter and we have got nothing back from nobody, the coroners or nothing," Ms Roe said.

"We want independent inquires and we want the truth and the justice."

Call for coroner to prioritise death-in-custody cases

Marc Newhouse, chair of the Deaths In Custody Watch Committee in WA, said delays were widespread in the Coroner's Court.

"In Western Australia it's not a new problem, it's been an ongoing problem for at least the last 10 years," Mr Newhouse said.

"We've had various explanations from the Coroner's Court isn't funding adequately to deal with the workload because they obviously do other inquests.

"There's also delays in the forensic area, the police reports, the medical tests and reporting that needs to be done."

Mr Newhouse said two other WA families were experiencing long delays waiting for death-in-custody inquests.

"The one which has completely traumatised the family members that I've been in contact with is the woman in Broome [Maureen Mandijarra] who died in the police lock-up. That's well over two years since she died in custody.

"The other one is Mr Bennell that's coming up to two years as well. There's a clear pattern."

The WA coroner's office said inquests would be held into those deaths but a date was yet to be set.

It said the necessary preparatory work on both cases was underway.

Mr Newhouse said deaths in custody should take priority in the Coroner's Court.

"Where there's a death in custody, these inquests should be expedited and held at the earliest possible time, given the trauma the families of deaths-in-custody people suffer," he said.

"The critical thing is that the person has died in custody, be that police, prison or in the process of arrest.

"Often families don't have access to information and that's just completely unacceptable. It's too long to wait."