The American based Human Rights Watch says the death in military custody of man in Indonesia's Papua province must be independently investigated.
The organisation says the death will only increase the local climate of fear and intimidation.
Eyewitness reports say Yapenas Murib, died after nine days in custody, following a crackdown after the raid on a military armoury earlier this month.
There have been reports that many of the 20 held in custody since the raid have been tortured, their possessions taken and some houses burnt down.
Yapenas Murib, eyewitnesses say, had been tied with ropes and dragged for three kilometres by soldiers.
A newspaper report of the autopsy says he died of an obstruction to his respiratory tract.
Human Rights Watch says there needs to be an urgent independent investigation into the torture allegations and the death, and that those responsible must be brought to justice.
A spokesman says the death could not have happened at a worse time, when Jakarta says it wants to relieve tension in Papua.