A coalition of Indonesian non-governmental organisations is urging the United Nations to send an investigator to Papua to make enquiries into the ambush which killed two Americans and an Indonesian.
The National Solidarity for Papua group says it also deplores statements implying that the Free Papua Movement, or OPM, was behind the fatal shootings.
It says that until the U.N. investigates, all parties, including the military, could be the suspected attackers.
A preliminary investigation run by the police and the Papuan Institute for Legal and Human Rights Advocacy, or ELSHAM, revealed that Kopassus, the army's special force, were at the crime scene when the shooting took place.
The Indonesian military has denied the finding and accused the OPM of being behind the attacks.
Police in Papua have questioned 21 military personnel and one civilian but no suspects have been found.
The military have also sent a team of investigators as has the U.S. embassy in Jakarta.