A Salvation Army worker identified as allegedly leading a fatal attack on Iranian asylum seeker Reza Berati on Manus Island in February is expected to be charged in Papua New Guinea.
The PNG national has been named in an official report into the riots which took place at the Manus Island detention centre between February 16 to 18 this year.
Mr Berati, 23, died in what the Government describes as a "disturbance" that saw another 60 asylum seekers injured, some seriously.
Immigration Minister Scott Morrison said a worker at the centre, employed by the Salvation Army, was involved in the attack on Mr Berati.
"Mr Berati was struck from behind by a service provider staff member - not G4S, it was actually Salvation Army," he said.
"And that other individuals including a G4S security contractor, it is alleged, were involved in rushing past him and kicking him and then a rock was dropped on Mr Berati's head."
The Salvation Army is acknowledging a former staff member is alleged to have led the attack on Mr Berati and says it will cooperate with all inquiries.
The report reveals Mr Berati was alive when he was treated by medical officers at an emergency triage centre on a wharf.
"But the medical staff knew from his injuries that he was not going to survive," the report quotes a medical officer as saying in a formal interview.
Mr Morrison said the riots represented a "terrible, tragic and distressing series of incidents that involved serious and indeed a fatal act of violence".
But he says if the asylum seekers had not started the violent protests, Mr Berati would still be alive.
"There would have been no incident that night had there been no protests, I think that's clear to say, but the protests in no way could ever justify what happened to Mr Berati or the other serious violent acts perpetrated on that night, under no circumstances in my view could that ever justify what happened," he said.
He has also rejected suggestions he failed to act when warned about inadequate security at the detention centre.
Report says asylum seekers' 'anger and frustration' led to protests
The report by former secretary of the Attorney-General's department, Robert Cornall, says asylum seekers' "anger and frustration" at the former Labor government's permanent resettlement plan, which meant they would never make it to Australia, led to the violent protests.
They began on Sunday, February 16 when asylum seekers were given answers to their questions about how soon their claims would be processed, and where they would be resettled if deemed refugees.
"The transferees' frustration and anger following that meeting resulted in disruption and violence in Oscar compound that evening and noisy protests," the report said.
That night, about 35 asylum seekers tried to escape from the Oscar compound when the gates were opened for dinner delivery, but were caught by guards.
The report says G4S guards entered the detention centre and "attacked transferees, causing physical injuries and some property damage".
The report alleges one asylum seeker "was attacked from behind by an unidentified PNG national G4S guard who slashed his neck, causing a 10 to 12 centimetre horizontal slit across his throat".
The asylum seeker has since recovered, but Mr Cornall's report notes he was "very lucky because, although the slash cut clear through the skin on his neck leaving a gaping wound, there was no internal damage".
Eight asylum seekers were arrested and charged by PNG police as a result of the Sunday night protest, according to the report, which does not say whether or not the G4S guard was charged.
Three-hundred asylum seekers gave evidence to Mr Cornall, who was charged with finding out "what happened" during the riots which led to asylum seekers being injured and, in the case of Mr Berati, killed.
The violent protests continued on Monday night when both asylum seekers and staff were injured.
Asylum seekers damaged property and breached the walls of Compound Mike, after which a mobile PNG police squad pushed over the fence and entered the centre.
The detainees say PNG nationals, expats and police entered the detention centre and dragged them outside to be beaten. Some allege they were able to buy "immunity" from beatings with cigarettes and also claim some were robbed.
It was during the riot on Monday that Mr Berati was killed.
The best opportunity to prevent such incidents recurring in future lies in addressing all of the underlying causes to minimise or even remove the factors that contributed to tension in the centre developing to a dangerous level.
An eyewitness has told investigators a PNG national employed by the Salvation Army led the attack on Mr Berati.
Two other asylum seekers were seriously injured in the same riot - one lost his right eye and another was shot.
Mr Cornall says the asylum seekers' frustration and anger at being denied access to Australia, and uncertainty about how or when they might be resettled on PNG were all contributing factors.
"The best opportunity to prevent such incidents recurring in future lies in addressing all of the underlying causes to minimise or even remove the factors that contributed to tension in the centre developing to a dangerous level," the report said.
Mr Cornall has made 13 recommendations, many relating to security at the centre. All have been accepted by the Government.
G4S predicted events that led to riots, documents show
Meanwhile, internal G4S documents obtained by the ABC show the company predicted the events that led to the riots, including the dates on which they were likely to occur.
"Information from various sources is still being presented that the demonstrations will continue and conclude in a larger event," the document dated 11 February says.
"A timeline of two weeks has been identified as possibly significant so the days leading to the 17/18 February 2014 continues to be of particular focus."
A third document dated 17 February, the date of the fatal riot, shows the threat of "external risk to the centre" was rated green instead of amber or the highest rating of red despite "significant disorder" in three of the centre's compounds the night before.
Labor's immigration spokesman Richard Marles says Mr Cornall's report shows the Government "dropped the ball".
"There were numerous warnings provided to the department but most particularly to the minister himself," he said.
"The Manus Island detention facility needs to provide safe accommodation for every asylum seeker in it ... this needs to be a guarantee," Mr Marles said.
But Mr Morrison has told the 7.30 program he authorised security upgrades late last year but was told it would take months for the work to be completed.
"Now that project was a four-month project. I was advised by the department. It's a four-month project to do what was required with both the CCTV, the infrastructure of the fence, and the lighting that was also required because this is a remote site.
"We shouldn't ignore that. It's a difficult place to put some of these things in place."
He also says Labor left his government an explosive situation.
"I think the Government has already learned the lessons ... because we could see it from the first couple of weeks I was Minister that the risks were there and we took every action we could as quickly as we could," he said,
"But it is my great regret that some of those actions weren't able to be implemented in time."
The Greens say the report shows the detention centre should be shut for good.
