An Aboriginal man has died in a Western Australian prison just days after his mother reportedly called the jail to warn that he was suicidal.

The WA Department of Justice confirmed that on Wednesday last week “a 30-year-old male prisoner was found alone and unresponsive in his cell at Acacia prison. Efforts by medical and custodial officers to revive the man were unsuccessful.”

The Corrective Services commissioner, Tony Hassall, has offered his condolences to the man’s family.

The death is being treated as a death in custody and WA police are investigating and preparing a report for the coroner.

According to Mervyn Eades of Ngalla Maya, a Noongar not-for-profit company that supports Indigenous prisoners and their families, the man in Acacia had been “having a hard time, had been in some fights, and had been seen with severe bruising”.

“He called out for help,” Eades said. “He called his mum and told her he was going to kill himself. She called the prison and told them. She went to visit but he wouldn’t come out to see her.”

Ngalla Maya was calling for the WA government to appoint an Indigenous justice commissioner to “oversee all these deaths in custody, look at recommendation after recommendation”, Eades said. “Nothing’s being done.

“We’ve had 46 [Indigenous] people die in 10 years in WA,” he said. “Someone needs to be held accountable.

“The system has failed another one of our young men. The medical attention they need is just not there. The mental health support they need is just not there.”

The Department of Justice said it was conducting an internal review into the circumstances surrounding the man’s death. “As a result of these ongoing investigations, there will be no further comment at this time,” it said.

Acacia prison is privately run by Serco Australia.