"I woke up like this this morning with this bloody depression thing. I woke up and I'm crying, I've been doing that all day. Yeah, it's been a bad day for me."

Della Roe sits in the sterile conference room of a Sydney law firm, a long way from her home on Western Australia's windswept mid-north coast.

She tells her lawyer she's had a tough day. She tells 7.30 it's been three years of tough days.

"It's been like hell. How else can I explain it, you know? No-one's been accountable for it, it's terrible. The last three years has been like hell."

It was three years ago this week that she got the call with the news her 22-year-old daughter was dead.

Ms Dhu — as she's now called for cultural reasons — was arrested and detained for unpaid fines in August 2014 in WA's Pilbara.

She died on her third visit within 48 hours to Headland Health Campus after complaining of feeling unwell while in custody. She was found to have died of septicaemia and pneumonia.

Ms Roe is now hoping lawyers will finally help her understand how that stint in the South Hedland Police lock-up ended in her daughter's death.

Case to expose 'rotten core of prejudice'

Ms Roe and her brother Shaun Harris made the trip to Sydney in a race against time to file legal proceedings against the WA Government before the statute of limitations is up.

They've got an experienced legal team on their side: human rights lawyer George Newhouse and Stewart Levitt.

They'll lodge a claim of misconduct leading to death in the Supreme Court of WA as well as a racial discrimination complaint in the Australian Human Rights Commission, which could ultimately progress to the Federal Court.

Ms Dhu died in police custody in South Hedland, WA, in August 2014. ( Supplied: Carol Roe )

Mr Newhouse is confident of their prospects of success in the wake of Mr Levitt's historic Federal Court victory on behalf of around 2,000 Palm Islanders over police racism following the 2004 riots there.

"Stewart has been extremely successful with the Palm Island case in highlighting endemic and systemic racism in the Queensland Police Service," Mr Newhouse says.

"These are issues that need to be exposed in WA as well and I think taking Stewart's approach and applying it to Ms Dhu's case will expose the rotten core of prejudice that exists both in the police service and also, surprisingly, in the health service in WA."

Mr Levitt wants Ms Dhu's case to be a turning point in Australian race relations.

"It's a very important case because this was an atrocity and there's too much tolerance in this country for this kind of repeated desecration of Indigenous families by people with the authority of the state," he says.

"And we need to set standards which all Australians adhere to."

What's changed in three years?

A coronial inquest last year found police acted inhumanely and that Ms Dhu's life could have been saved if doctors at the Hedland Health Campus had properly diagnosed her illness.

An internal police investigation, overseen by the Corruption and Crime Commission, found there was no criminality.

Eleven officers underwent "disciplinary measures" due to their lack of compassion towards Ms Dhu, but none of them were sacked or charged.

In relation to the Hedland Health Campus, staff were reportedly counselled and an independent review of procedures conducted.

The coroner also recommended the WA Government consider introducing a Custody Notification Service, which the family and Deaths in Custody Watch Committee had been pleading for.

It is still yet to be introduced.

Mr Newhouse says lessons need to be learned from this case.

"It just should never happen again and reforms need to be put in place as a matter of urgency," he says.

"It's three years since her death and time's up. Time's up. These reforms need to take place and I'm hoping that the case will lead to real reform in WA."

WA Police could not comment on specific civil action against it but said that since Ms Dhu's death it had made a number of changes to its custodial policies and procedures to ensure the safety and preserve the dignity of people in their care.

A spokesperson for WA Health Minister Roger Cook said WA Country Health had conducted an extensive review into Ms Dhu's death and made systemic changes and improvements to its service.

The Department of Health was working with police to improve the provision of medical information about detainees to police, the spokesperson said.