As investigators piece together how this week's riot on Christmas Island unfolded, a clearer picture of the man whose death prompted the destruction is also starting to emerge.

Iranian Kurd, Fazel Chegeni, arrived by boat in Australia four years ago to seek asylum.

He was granted refugee status but was held in the Curtin Detention Centre for final security checks before being granted a visa.

It was there an incident occurred that shaped the rest of his life.

Mr Chegeni was involved in a fight inside the detention centre's canteen.

CCTV vision obtained by 7.30 shows Mr Chegeni pushing another detainee who then hits him with a plate.

The fight then degenerates into a brawl.

It is all over in less than a minute, but the brawl condemned Mr Chegeni to never being settled in Australia.

Conviction sentences Fazel to 'life in detention'

Sorry, this video has expired CCTV shows Fazel Chegeni in brawl at detention centre

More than a year later, Mr Chegeni and four other men were charged with assault.

His solicitor, Matthew Wilson, said a strategic decision at the trial backfired, sealing Mr Chegeni's fate.

After initially entering a plea of not guilty, the five men changed their plea on legal advice when it appeared that the court was unlikely to be sympathetic to their argument of self-defence.

"Fazel and our other four clients elected to plead guilty, allowing them to express their remorse for their involvement in the fight and throw themselves at the full mercy of the court," Mr Wilson said.

The Perth magistrate hearing the case was Barbara Lane.

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"Sadly, Magistrate Lane showed no mercy," Mr Wilson said.

Mr Chegeni and the other men were convicted of assault and sentenced to six months jail.

Mr Wilson said this was effectively a life sentence.

"Any person who receives a conviction as part of their sentence for an offence committed in migration detention is automatically denied the right to receive residency in Australia," he said.

"They fail the character test, and effectively for a refugee, this amounts to a life sentence.

"They cannot be returned to their country of origin and they will see out their days inside the migration detention system in Australia."

Mr Chegeni's lawyers appealed against the sentence, but the West Australian Supreme Court found it was excessive and overturned it.

But, crucially, the conviction remained.

"And it beggars belief that a person with the overwhelmingly appalling circumstances that Fazel had been through could be treated so cruelly," Mr Wilson said.

Magistrate Lane later resigned under a cloud over another case.

She declined to comment to 7.30.

Questions raised over why Fazel was moved to Christmas Island

After his conviction, Mr Chegeni was moved to detention centres around the country.

Refugee advocate Pamela Curr said his mental health was deteriorating.

Space to play or pause, M to mute, left and right arrows to seek, up and down arrows for volume. Watch Duration: 7 minutes 44 seconds 7 m Family of dead Iranian refugee question his death on Christmas Island ( Madeleine Morris )

"I'm hearing from his friends he was losing hope that he [would] ever been released," she said.

Earlier this year he was moved to Christmas Island, joining around 200 other men in immigration detention.

Many in the detention centre are convicted criminals, awaiting deportation from Australia after serving prison sentences.

Pamela Curr said Christmas Island was no place for refugees or asylum seekers.

"Why was this man, who was so obviously ... ill, sent to Christmas Island?" she asked.

"The minister says it's a place for the worst of the worst.

"Fazel was a gentle man who was found to be a refugee."

Family in mourning, seeking answers

7.30 contacted Mr Chegeni's family, who live in a rural area of Iran near the border with Iraq.

Mr Chegeni's brother, Ali Asgar, said in a video message that the family was in mourning.

"We ask the Australian Government to transfer the body of my brother according to its legal and humanitarian duties," he said.

"We want to know why he died, and who caused the death."

A spokesman for the Immigration Minister, Peter Dutton, declined to comment, saying the matter was the subject of a police investigation and would be the subject of a coronial inquiry in West Australia.