WA Corrections denied young people in the ISU were isolated, and said they were placed there “based on the individual level of care and support a young person requires”, and came with “significant oversight”.
“They are provided with programs, education and daily sports and games programs with other young people and staff. They have access to the same privileges as other young people,” a spokesman said.
He said the department had referred allegations of isolation to the department’s investigative services, and could not comment on matters subject to investigation.
His mother said he and the others should not go unpunished for their part in the incident – her son faces charges – but eight months in the ISU and the treatment he had been subjected to were wrong.
“Banksia Hill has demonised him. He’s not being rehabilitated, he’s being contained, and that’s what we do to animals,” she told Guardian Australia.
“I don’t want any other mother to have to give a story like this ever again. I want my son and the other boys to be released back into general population. [My son], he hasn’t done anything since May that would warrant still being in the Harding Unit. I want answers.”
She said she wanted to review all CCTV footage of her son and the other boys’ time in the ISU.
“Show me. Show me that you didn’t do what my son said you did,” she says, angry and tearful. “Show me that you’re not mistreating these kids. You know, if you’ve got nothing to hide, and what you’ve done is right, then show us the footage.”
A letter from the 18-year-old late last year revealed a level of desperation he had been hiding from his mother, including that he felt he was becoming “institutionalised” and was continuously self-harming. Banksia Hill had never told her, she said.
“I don’t ever want another mother to find out through a letter that her baby boy feels like he wants to die sometimes,” his mother said.
“I had no idea that he cut his arms to relieve pain and stress, and to find out that he wore jumpers to visits on really hot, 40-degree days to hide the scars from his family was just absolutely heartbreaking.”
WA Corrections said it was unable to comment on an individual case for confidentiality reasons, but the spokesman said separately the ISU provided “a safe environment to case manage highly complex young people”.
He said young people requiring targeted care and intervention as a result of being at risk of self harm or risk to others might be placed in the ISU.
Solonec said Amnesty had written to the department twice in the last month requesting an “independent, urgent and thorough investigation” into the allegations and the Harding Unit itself, without response. But she understood the department was looking into individual claims.
“Holding children in solitary confinement as punishment for long periods has been proven to cause profound neurological and psychological damage, including causing depression, panic attacks, paranoia and anger,” Solonec said.
Amnesty also called for WA’s “weak” legislation around solitary confinement to be amended and made consistent with international law.
The boy’s mother said she feared going public could have negative consequences for her son, who she described as respectful and caring, but they both wanted to advocate for other juvenile detainees as well.
She said things had been better for her son in recent months but she had no doubt he was being isolated and mistreated, and that other kids potentially still were.
She did not know if he would be jailed for extra time over the May incident, but she said the Australian government wanted him gone: he received a deportation notice from the department of immigration in August.
“I feel like he’s been punished over and over and over again.
“I suppose it’s very hard for other people to understand [being] told you’ll now have your family ripped apart by deportation, to have to tell his brothers and sister that they may not get to see him again for years and years and years.”
Her son has lived in Australia since he was 10, and has no family who could support him in New Zealand.
The alleged mistreatment of the teens was the latest in an “avalanche of horrors” from Banksia Hill, Solonec said.
A damning report on the facility last year by independent inspector of custodial services, Neil Morgan, revealed a facility that was “failing the basics”. He said it should be closed and replaced with a purpose-built facility.
In 15 months from the beginning of 2016 there were six attempted suicides and 272 incidents of self harm at Banksia Hill. Critical incidents and assaults on staff more than doubled in 2016.
Morgan’s report also uncovered “credible claims” that electronic records were deliberately entered incorrectly, and criticised the department for failing to provide CCTV footage.
It followed earlier findings that a 2013 riot was “entirely predictable” and that there was evidence some young people had been denied their required exercise time.
The federal Department of Home Affairs has been contacted for comment.