An Indigenous death in custody has sparked an investigation by Queensland Corrective Services and police after the man was found unresponsive in his cell.
The man, identified as Glen Francis via a family spokesperson, could not be revived at the Maryborough Correctional Facility on Tuesday.
"Responding officers commenced CPR and Queensland Ambulance Service attended the centre, however he was unable to be revived," QCS told AAP in a statement.
"The centre was placed into lockdown as a precautionary measure, and officers are engaging with other prisoners in the unit.
"Queensland Police Service is investigating the circumstances surrounding the death, and QCS is assisting with their investigation."
A spokesperson for the Francis family told AAP the 43-year-old was in the facility along with his brother, and had sciatica in his legs and hips, with calls for medical assistance not followed up by the facility.
"I was told that he was bed ridden, and that's when I requested and contacted Corrections and said that he needs to be taken to the hospital," Aunty Alex Gator said.
"It could've been his heart, his chest or his legs. All I was told was that he was bed ridden and it's very serious.
"They told his mum that he died of natural causes.
"They failed in their duty of care to provide a service to Glen."
Aunty Gator also said the family and representatives had met with correctional authorities recently to discuss treatment of Indigenous inmates, with accounts of racial discrimination.
"Since we spoke out there's been five officers that came forward and said 'Yes, there's racial discrimination'," she said.
"They get an attitude towards Aboriginal people. They should not be working in these correctional centres."
QCS Professional Standards are on site to review the circumstances from a prisoner management perspective, while the death is under investigation by Queensland Police's Corrective Services Investigation Unit.