The New Caledonia State Prosecutor says bullet fragments found in the body of Jean Marie Goyeta show he was shot with a 270 calibre rifle.
The young Kanak man was caught in cross fire in January last year during violent confrontations between Kanaks and settlers from Wallis in the village of St Louis near Noumea.
Laurent Vili, a Wallisian, was arrested in France last August and charged with the murder.
On the day Mr Goyeta was shot Vili had used a 270 calibre gun.
Mr Goyeta's body was disinterred two weeks for an autopsy which Vili's lawyers hoped would clear him because the man's wounds had indicated he was shot by a smaller calibre rifle.
But they say the results don't mean their client is guilty because 270 calibre guns are common in New Caledonia and were used by many gunmen during the St Louis dispute.
The conflict was resolved late last year after local authorities and the French High Commissioner promised to resettle all the Wallisian families away from St Louis.