Lawyers representing the family of Kumanjayi Dempsey say her death was "preventable", and are suing the Northern Territory Government for negligence.
The 44-year-old died after collapsing in her cell at the Tennant Creek police watch house, two days after being arrested on Christmas Day in December last year.
On Wednesday, a Sydney based law firm — representing the family of Ms Dempsey — filed civil proceedings in the Federal Court against the NT Government, claiming that the NT police breached their duty of care to Ms Dempsey following her arrest.
In a statement, O'Brien Criminal and Civil Solicitors Principal Solicitor, Peter O'Brien, said Ms Dempsey's death was preventable.
"Ms. Dempsey deserved humane and proper care," Mr O'brien said.
"The failure of the NT police to ensure this has resulted in a preventable death that has devastated her family and left her five children to grow up without a mother," he said.
In January, NT police confirmed an autopsy was unable to determine her cause of death.
At the time the NT Police Assistant Commissioner Peter Malley said investigations indicate Ms Dempsey suffered a "medical incident".
'Not properly evaluated'
The legal firm are alleging that Ms Dempsey's state of health was not properly evaluated and that she was not provided access to her daily medication for Rheumatic Heart Disease.
They also claim the cell she was kept in smelt strongly of sewerage and the only access to water was from a tap directly above a dirty toilet.
Among the allegations are claims Ms Dempsey was not adequately monitored by members of the NT Police Force present at the watch house.
"The police have a duty to protect citizens in their care and not neglect them to the extent they did Ms. Dempsey," Mr O'Brien said.
What happened on 27 December 2025?
The Tennant Creek mother was found unresponsive in her cell at 1:03pm on December 27, 2025.
Police say she was arrested and charged over an incident on Christmas day and had spent almost two days in the watch house before her death.
NT Police say CCTV footage showed Ms Dempsey falling to the ground at 12:34pm, minutes after a routine cell check. She was found unresponsive at the next cell check half an hour later.
Unlike other watch houses in the Northern Territory, no nurse is stationed at the Tennant Creek watch house and health assessments are performed by police.
The Assistant Commissioner said Ms Dempsey presented no visible injuries and made no disclosures about underlying health conditions when she was admitted to the watch house.
Family seeking redress
Principal Solicitor O'Brien says the family is seeking redress for the suffering caused by Ms Dempsey's death and to uphold the broader issue of Aboriginal deaths in custody.
“It is extraordinary that in the year of the 35th anniversary of the Royal Commission into Aboriginal Deaths in Custody that we are still seeing preventable deaths happening in police custody," he said.
"We are seeking redress not only for the suffering of Ms. Dempsey’s family, but also to uphold the broader issue that there should not be preventable deaths in police custody, ever."
More than 600 Aboriginal and Torres Strait Islander people have died in custody since the conclusion of the Royal Commission in 1991.
