Last Friday relatives of Fariborz Karami finally said goodbye to the 26-year-old, an athletic and intelligent dentistry student who had married just a short time before taking his life inside a tent on Nauru.

It had been more than three months since he died, and many years since doctors first raised concerns about his mental health with immigration detention authorities.

At Mount Gravatt cemetery in Brisbane, friends and relatives of Karami gathered under a small marquee, taking turns to kiss and embrace a white coffin adorned with silver handles, red roses resting on its lid.

“I never thought the rubble of cold soil would separate us from each other,” one relative who could not be named told Guardian Australia. “He was the only man who supported me in my life. But how could he leave me alone with my deep wounds?”

The funeral in Brisbane last week

Before Karami died, his mother begged for help for both her sons, and continued to advocate for her youngest son after Karami was gone.

“Often, I told you and I wrote to you that my sons are depressed and exhausted ‘please help a sick and feeble mother’,” she wrote to Australian Border Force. “But, instead of support, you replied that if I couldn’t tolerate it, I should return to my country.”

Border Force long insisted that Karami could only be buried in Nauru or Iran, at the family’s cost. The home affairs department referred media queries to Nauru’s government.

The official detention centre arrangements between Australia and Nauru, newly obtained by Guardian Australia, reveal that it is enshrined in their contract that asylum seekers and refugees who die on Nauru will receive no Australian assistance except in consideration of “exceptional” requests.

“Burial or other funerary practices for transferees will occur in Nauru unless alternative arrangements are made by the deceased’s family,” it said. “Financial support will not be provided to the family by the Australian government for repatriation of the deceased.”

In Nauru Karami’s mother pushed for a funeral in Brisbane. That way, she said, at least other relatives could visit her son’s grave. She could not return to Iran for fear of persecution, and Nauru’s temporary offer of refuge meant she would one day have to leave.

More than a month after he died Karami’s body was flown to Queensland. The cost of that flight as well as Friday’s funeral were covered by unnamed philanthropists.

Fariborz Karami, 26, on Nauru

Karami was the 12th person to die in Australia’s offshore detention regime. Many more have come close, either through illness or suicide. A growing crisis in mental health on both Manus Island and Nauru is causing fear and panic among doctors and refugee advocates.

There are increasing reports from island sources that authorities are threatening to arrest anyone who attempts suicide, and on Saturday the Nauruan government ordered one of the only organisations providing mental health care, Médecins Sans Frontières, to leave the island.

Dozens of people are being brought to Australia under court-ordered medical transfers, resisted by both the Australian and Nauruan governments. But Nauruan government officials – who are not under the jurisdiction of Australia’s federal court – have begun dismissing the orders and the medical advice that prompted them, refusing to allow air ambulances to land.

• In Australia, the crisis support service Lifeline is on 13 11 14. In the UK Samaritans can be contacted on 116 123. In the US, the National Suicide Prevention Lifeline is 1-800-273-8255. Other international suicide helplines can be found at www.befrienders.org