The president of the Papua New Guinea province of Bougainville, Joseph Kabui, is urging rebels to dig up the body of the former rebel leader Francis Ona.
Officials say Mr Ona died from malaria in July in his rebel zone in the south of the main island.
No post-mortem examination was carried out.
Mr Kabui says Mr Ona's family, and people throughout the province are still questioning how he died.
The provincial police commander, Joseph Bemu, says his officers weren't allowed to approach the rebel-held zone.
"We were not allowed to go near, or to the funeral, it was done in his village at Guava. It is a no-go zone, we respected that and we didn't go."
Mr Bemu says normally in any sudden death outside the rebel zone, police prepare a report for the coroner, who then decides whether to act on it.
A reporter who attended Mr Ona's funeral wasn't allowed to view his body.