Sources on Manus Island said cleaning staff had scrubbed clean the detention centre - including the area where Mr Barati died - the morning after the fatal violence of February 17. There are concerns this could compromise the investigation into his death.

Bullet casings and bullet holes at person-height in the centre walls were also found, staff who work at the centre said.

It appears the attack that resulted in Mr Barati's death, and injuries to more than 60 asylum seekers, was an orchestrated response to a rolling protest that involved asylum seekers chanting ''F--- PNG'' and baring their buttocks.

An account pieced together from interviews with staff asserts that the lights were turned off in the area where the asylum seekers were injured shortly before local police and locals employed by security contractor G4S and the Salvation Army entered the centre.

The account of Mr Barati's death is consistent with the one related by relatives who have spoken with a cousin who witnessed the attack.