Victorian Greens Senator Lidia Thorpe has called the justice system "deeply racist", following the deaths of three Aboriginal people in custody over the past week.
An Aboriginal man died in Victoria's Ravenhall Correctional Centre on March 7.
In NSW, a man in his 30s and a woman in her 50s have died in the past week, but their deaths were only revealed under questioning during a NSW parliamentary hearing two days ago.
"This is relentless and traumatising for our people," Ms Thorpe said in a statement on Thursday.
"At this point you have to say, the system is deeply racist."
The Victorian man's death has been reported to the coroner, who will formally determine the cause of death.
Corrections Victoria said his family had been notified and a smoking ceremony arranged.
"We recognise that all deaths in custody have impacts on family members, friends, corrections staff and the Aboriginal community and we're working to ensure they are provided with the support they need," Corrections Victoria said.
The chief executive of the Victorian Aboriginal Legal Service, Nerita Waight, told AAP the lack of change since the Royal Commission into Aboriginal Deaths in Custody was "shameful".
"It is traumatic, it is frustrating, it is rage inducing," she said.
The legal service says in the 30 years since the final report of the royal commission, 455 Aboriginal people have died in custody.
"This death highlights the urgent need for sweeping reforms to the justice system," Ms Waight said.
The investigation into the latest Victorian death will be held under new rules for dealing with Aboriginal deaths in custody, requiring prompt investigations, and for Aboriginal families' voices to be heard during the inquest.
But VALS says the government has not provided the funding for it to participate in the new process.
"I just don't know what more it will take for them to make policy based on good advice," Ms Waight said.
"We again ask the Victorian government to properly fund our services so that we can make a real difference for our people."
Earlier this week, the Victorian government announced a "truth-telling" commission to investigate the effects of colonisation on Victoria's Indigenous community.
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Australian Associated Press