A former detention centre guard says he is not surprised an asylum seeker has died from an infection he caught at Manus Island because he witnessed filthy living conditions inside the facility.

Hamid Kehazaei cut his foot at the detention centre about three weeks ago, developed septicaemia and was sent to Brisbane's Mater hospital.

The 24-year-old suffered a heart attack and was later declared brain dead.

His family in Iran made the decision to switch off Mr Kehazaei's life support late on Friday.

Former Manus Island detention centre employee Beau Mitchell has told the ABC he is not surprised at Mr Kehazaei's plight after recording evidence of poor hygiene inside.

"There's no air conditioning, the beds are extremely close together. The living standards are pretty quite filthy," Mr Mitchell said

"Often they'd be standing on concrete to have a shower that was literally falling apart underneath them, just completely rotting away."

Hamid Kehazaei died in Brisbane's Mater hospital after suffering a heart attack. ( Supplied: Ian Rintoul/Refugee Action Coalition )

Mr Mitchell, who was employed as a guard with contractors G4S and Wilson Security, says he used secret cameras to record some of the conditions inside the compounds which house asylum seekers.

He says he quit his job in June disgusted at what he saw, but insists medical staff at Manus Island are trying to do their best to look after detainees.

"The people that were actually working there did a fantastic job with what they had to work with," he said.

"They were seen on almost on a triage basis. Obviously if it was something quite severe they'd be seen quickly but if it wasn't an emergency it was a 2-3 day wait normally."

Family to investigate claims of negligence

The family of Mr Kehazaei has enlisted the help of a lawyer to investigate whether they have a case of negligence against the Australian Government.

Lawyer Ruth Hudson will be representing the family and believes there are obvious signs of negligence.

"This wasn't a fatal injury until the Government made it so," she told the ABC's AM program.

Space to play or pause, M to mute, left and right arrows to seek, up and down arrows for volume. Listen Duration: 4 minutes 30 seconds 4 m 30 s Family of dead asylum seeker want justice: lawyer ( Elizabeth Jackson ) Download 8.3 MB

Ms Hudson said the family, who are seeking "justice for Hamid", were given very little information about the treatment or events prior to Mr Kehazaei's transfer to the Mater Hospital in Brisbane.

"They want me to find answers as to why their son is now gone, in circumstances where his life could have been saved," she said.

Ms Hudson said an investigation was needed to establish how Mr Kehazaei could have died as a result of the non-threatening condition while in Australian care.

"This just does not happen in a civilised society," she said.

Ms Hudson said she would investigate three critical points in the timeline of Mr Kehazaei's treatment.

"There is a possibility there was an inadequate initial diagnosis, potential failure to transfer him quickly enough to Australia; and also a failure to provide adequate treatment," she said.

"Unfortunately, there has not been a great deal of information provided prior to Hamid being transferred to the Mater. So there is still some question as to the specific timeframe."

The Immigration Department's chief medical officer has been asked to review the case.

"Any review needs to be an independent, open inquiry into what has happened. Otherwise we just don't feel that justice will be properly served here," Ms Hudson said.

Social Services Minister Kevin Andrews said he was satisfied the case was being properly investigated.

"I understand the chief medical officer of the Immigration Department will be inquiring into this and I understand the matter's been referred to the Queensland coroner, so there's quite appropriate legal, administrative inquiries going ahead," he said.

"We should await the outcome of those inquiries before we speculate or make any further comments."

The Federal Opposition said the family deserved to know whether Mr Kehazaei received full and proper medical care.

The family requested that his body be returned and repatriated to Iran so that a funeral service can take place.