Cleveland Dodd was found unresponsive inside a cell in the trouble-plagued youth wing of a high-security adult prison, south of Perth, in the early hours of October 12, 2023.
The 16-year-old was taken to hospital in a critical condition and died about a week later, becoming the first juvenile to die in a West Australian detention facility.
His mother, Nadene Dodd, says coroner Phil Urquhart must determine who was responsible for Cleveland's "horrible" death when he delivers his findings on Monday into the expedited and long-running inquest.
"It has been incredibly painful," she told AAP.
"Losing my son shattered my world. Some days I can breathe. My grief is with me every minute. I don't even know what healing means."
No child should ever have to go through what Cleveland did at the Unit 18 detention facility before he died, Ms Dodd said.
"Unit 18 was a death sentence for my boy," she said
"I want accountability. If people failed my boy and I believe they did ... then they should face consequences."
The coroner's findings should be strong enough that prosecutors and police have no choice but to act, Ms Dodd said.
Any recommendations must also include demanding the immediate closure of the facility inside Casuarina Prison, she said.
"I want the coroner to be strong and clear: close Unit 18 and replace it with 24/7 support," she said.
"I know there will be thousands of words, but instead I'd be content with hundreds of actions."
Mr Urquhart previously said youth justice was in a crisis at the time of Cleveland's death and indicated he may recommend Unit 18's closure, as well as a special inquiry into how it came to be established.
The coroner said inquest evidence supported findings the justice department had failed to properly supervise Cleveland before he fatally harmed himself.
Staff described the appalling conditions in which the young people were being detained during the inquest and the chaotic operating environment at Unit 18, with some saying it was a "war zone".
In the 12 days before he harmed himself, Cleveland spent between one and two hours out of his damaged and unfurnished cell per day.
Former Department of Justice director general Adam Tomison conceded it was "cruel, inhuman and degrading" treatment when cross-examined.
The inquest heard Cleveland self-harmed about 1.35am and staff didn't open his cell door to help him for more than 15 minutes, with paramedics arriving a further 15 minutes later.
The teen was partially revived and taken to hospital but suffered a brain injury because of a lack of oxygen.
He died, surrounded by his family, on October 19, 2023.
The WA government has previously said many improvements have been made in youth justice since Cleveland died and that a purpose-built facility to house detainees from Unit 18 will be completed within three years.
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