There has also been the alleged rape of a camp worker and another local guard had his hand severed.
The violence has prompted the Australian Greens to say Manus is in meltdown.
The Manus Province police commander, Alex N'Drasal, says the dead man, who had been drinking home brew, was attacked by locals in a settlement near the camp.
He says another man, who had also been drinking, had his hand cut off in the town on Saturday.
That man is currently in intensive care at Lorengau Hospital.