Police say the 39-year-old man, whose name hasn't been released, died in the early hours on February 10 after losing consciousness in police custody.
It's the second Indigenous death in custody at Townsville, a city in north-eastern Queensland, in the last six months.
Townsville Police Chief Superintendent Kev Guteridge said the death occurred during a 'reasonably routine' callout to an incident in the suburb of Mount Louisa around 1.20am.
"Following a brief altercation with a male person there, the male person was taken into police custody," he said.
"Sadly during the taking of that man into custody, he lost consciousness. An ambulance was present at that time. Despite extensive attempts by police and paramedics to revive the man prior to his transport to Townsville Hospital, those attempts were unsuccessful and unfortunately the man was unable to be revived and tragically lost his life."
"Once again this is déjà vu."
Townsville activist Gracelyn Smallwood said the scenario was becoming all-too-familiar to the local Indigenous community.
"Once again this is déjà vu," she told NITV News.
Professor Smallwood said the family was receiving legal advice from Levitt Robinson, the same legal team who helped Lex Wotton win a landmark racial discrimination case against the Queensland government in 2016.
She said the family had been advised not to speak publicly at this time.
As with any death in custody, the incident will be the subject of a coronial inquest.
Chief Supt Guteridge said the matter was also being investigated by the Ethical Standards Command, overseen by the Crime and Corruption Commission.
"Critical to that investigation is going to be the body-worn camera footage that has been taken from the police officers that were at the scene at the time," he said.
"This is a very, very tragic set of circumstances and will certainly have an effect on the community of Townsville."
The Townsville death in custody comes three days after 31-year-old Patrick Fisher died in Sydney after falling from a balcony during a police altercation.