Fiji police say only seven aspects of the coup remain to be investigated.
Among these are the financing of the coup, the removal of the former president, Ratu Sir Kamisese Mara, those who were sworn in as members of Speight's failed administration and several diplomats, including the former police commissioner, Col Isikia Savua.
The acting police commissioner, Moses Driver, has told the Fiji Times that most of these files had been open for some time but others had been opened only recently.
Mr Driver says they have to charge those who were sworn in as ministers after the coup.
But they cannot go ahead with the evidence they have in other cases because it might not survive in court.
Six people are already facing charges for being sworn in, including the vice-president Ratu Jope Seniloli, the deputy speaker of parliament Ratu Rakuita Vakalalabure and the current sports minister, Isireli Leweniqila.