Detained on Christmas Island, former child soldier William Yekrop is a man without a country.
Mr Yekrop grew up during a bloody civil war in South Sudan before it became an independent state.
Held in immigration detention for the past decade, he turned to bodybuilding and became a personal trainer to stay sane.
He is allowed outside for two hours a day.
"My mental health is getting worse," the 39-year-old told AAP.
"I'm losing it. I can't sleep at night. I wake up two or three times every night with nightmares.
"This place is not built for humans to stay here a long time."
Mr Yekrop said he was approached once a month by Australian Border Force officers encouraging him to voluntarily return to South Sudan, which seceded from Sudan in 2011.
Having fled to the Sudanese capital of Khartoum aged four and then to refugee camps in Egypt, Mr Yekrop has no documentation to prove he is a citizen of South Sudan.
He cannot return to Sudan, where he was born, which has been in the grip of a proxy war between military and paramilitary forces.
Hundreds of people have been killed in the conflict, thousands more injured and millions displaced.
Mr Yekrop told border force officers he could not return to Africa and said he should not be in detention.
"I don't think the ABF understand people's cases," he said.
"They just act like it's a normal routine to get people to sign."
Mr Yekrop and his family arrived in Australia as refugees in 2003.
Soon after, he got caught up with bad people and starting committing petty crimes.
Mr Yekrop was caught drink driving twice and jailed for more than 12 months.
As a consequence, his visa was cancelled on character grounds in 2012.
He was placed in immigration detention as a non-citizen in May 2014.
His application for another protection visa is still pending.
His case was raised by the UN Human Rights Council in 2018, which said his detention constituted an arbitrary deprivation of liberty and was not necessary or proportionate.
Mr Yekrop's hope for release lies with Immigration Minister Andrew Giles, who last month intervened to release another stateless man.
"I need a second chance," he said.
"I'm a changed person, just want another chance to take care of my family."
For Mr Yekrop, the separation from his elderly mother and 14-year-old daughter gets harder the longer he is in detention.
"My mum’s older now. Who’s going to take care of her?
"Sometimes when she calls me she cries and asks me why it keeps dragging on year after year."
Human rights lawyer Alison Battisson said one in 10 immigration detainees across Australia were displaced people without citizenship of other countries.
Katie Robertson, a research fellow at the University of Melbourne, said Australia did not have a legal framework for identifying and processing stateless people.
"That’s problematic because it means stateless people cannot get protection under our refugee framework," she said.
"It means they are subjected to indefinite detention in Australia because they have no other form of visa to apply for."
Ghader Mohamed, an Ahwazi Arab from Iran, likened his years in immigration detention to a life sentence.
The Ahwazis, an Arabic-speaking minority of about a million people, have occupied the oil-rich Khuzestan province in western Iran for centuries.
Mr Mohamed said as an activist, speaking up against the government forcibly taking his land put him in the regime's crosshairs.
He travelled to Indonesia on a fake Iranian passport and came to Australia by boat in 2010.
He was detained on Christmas Island and in Darwin before being granted a bridging visa in 2015.
When it came time to renew his three-month visa, Mr Mohamed was told he was being detained for procedural reasons, but said he had been stuck there indefinitely.
"When I ask them they tell me we didn’t find you as a refugee and you have to go back, but I can't go back because 100 per cent I will get killed by the Iranian government," he said.
Mr Mohamed said the centre was filthy and alleged detainees were served expired food.
He also accused guards of targeting him.
"Some of the officers would tell other detainees that this guy is a terrorist and a danger to the community and I used to have fights every single day about this," he said.
"I left my country because I had problem with the government, my life was in danger.
"I came to this country for hope for assistance and now look what they've done to us."
Australian Border Force was contacted for comment on the claims made by both men, but said it did not comment on individual cases.
The agency said where an "unlawful non-citizen" had exhausted all avenues for appeal, they had no legal basis for remaining in Australia and were expected to depart.
"Those who are unwilling to depart voluntarily may be subject to detention and removal from Australia," it said.
"Unlawful non-citizens are only removed if the department is satisfied that their removal would not breach Australia’s non-refoulement obligations or other international obligations relating to the return of non-citizens.
"Removals from Australia are undertaken as soon as reasonably practicable through both voluntarily and involuntary pathways."
