Papuan human rights activists, investigating the killing of three people near the Freeport Mine, say they are more convinced than ever there was no involvement by the separatist Free Papua Movement or OPM.
The shooting attack on August 31 has been blamed on the OPM which has consistently denied it.
A team from the human rights group, Elsham, has been in Timika, the main town near the mine, for the past ten days.
Their spokesman, John Rumbiak, says they have met all the OPM leaders operating in the area, and are certain they were not involved.
He says the organisation in the area lacks the sophistication to have carried out such an attack.
Mr Rumbiak says the local OPM had two guns between them, and no bullets.
He says their investigation and that of the police has been continually hampered by the military.
Some observers believe the Indonesian military may have orchestrated the attacks.