US police will be in Indonesia next week to help investigate last August's killings of two American school teachers and an Indonesian in Papua province.
A US official has told Reuters news agency that he expects several FBI agents to arrive in Jakarta and that they and the Indonesian police and military would likely need to go to Papua.
Indonesian police have said some weapons used in the attack near the Freeport mine were the same type as those carried by troops stationed near the site.
The military has denied any wrongdoing in the attack which the US has described as a terrorist act.
Observers say if any military hand were found in the ambush it could cause problems in Jakarta's bid to restore normal military ties with the US which were slashed because of the Indonesian violence against East Timor's vote to break away.