An attempt to delay the start of an inquest into the death of a thirty-year-old Noongar and Torres Strait Islander man due to what lawyers described as "hopelessly inadequate" evidence has failed.

Lawyers representing the family of Jomen Blanket at the inquest in Perth which started on Tuesday asked for the delay in order to gather more information about the circumstances surrounding his death.

Mr Blanket was found dead in Acacia Prison, Western Australia, on June 12, 2019 after his family complained to prison staff about his care and conditions.

The National Justice Project is representing the family at the inquest and described the available evidence as "hopelessly inadequate".

Mr Blanket's mother, Karen Blanket, spoke outside the coroner's court in Perth during day one of the inquest.

"I spoke to my son many-a-time in Acacia and he was not getting the care he needed," she said.

"Our whole family are devastated. He leaves a partner and three kids. He was a beautiful kid and soul and we miss him.

Karen Blanket, supported by family members outside Perth's Central Law Courts. Photo by Giovanni Torre.

"My family has now been waiting for three long years for the inquest to start so we can get the truth of how this was allowed to happen, and hold the system to account.

"We are Mr Blanket's family and we want answers."

Ms Blanket said despite the long wait, she would have preferred the start of the inquest be held off to allow for more evidence to be gathered.

"We have evidence, good evidence, but we need more," she said.

"I am frustrated, there are other families who have lost boys, sons, and daughters.

"These are our children, and they have their next generation, their kids left without their father or their mother because of the treatment they got."

Ms Blanket said her son was a good father who was a strong role model and cultural teacher for his family.

A relative of Mr Blanket noted it was the first time he had gone to prison.

Ngalla Maya chief executive Mervyn Eades said Mr Blanket's family was one of many Aboriginal families searching for accountability after the death of a loved one in prison.

Mervyn Eades, Karen Blanket and Megan Krakouer outside the inquest.

"The lawyer wanted it to be put off because the evidence is inadequate, the evidence from all the departments," he said.

"This is damning, this is why we never get accountability for deaths in custody."

Mr Eades said Aboriginal people were sick of governments ignoring coronial court recommendations.

National Suicide Prevention and Trauma Recovery Project spokeswoman Megan Krakouer said authorities had failed Mr Blanket.

"The family did not know he had self-harmed 10 times - the department knew and the family did not know," she said.

"This was a young man crying out for help and there was no communication with the family.

"People in the prison knew what the circumstances were and they begged officers to put him with a family member."

Ms Krakouer said there needed to be political will to turn recommendations into action.

A spokesperson for the Western Australian Department of Justice said all aspects of the case are now in the jurisdiction of the State Coroner and it would not be appropriate for the department to comment.

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