It will be controlled by who ever is in charge of the accident investigation. Since it appears the plane crashed in international waters it would normally be the State of the operator. However in this case it seems the Malaysians have handed off the grunt work to the Australians. It will be interesting to see if and when stuff is found if the Malaysians try to take control or just contract the whole thing out to Australia. Normally they would not have had any standing in this flight. It wasn't going to or from there, it's not their airline or airplane and it wasn't made there.