Authorities in India have released the preliminary results of their investigation into the the Boeing 787-8 Dreamliner crash in June that killed 229 of the 230 passengers aboard and all 12 crew members.

An official report on the world’s deadliest aviation accident in a decade, seen by CNN, has answered one key question – but raised others.

A preliminary report released on Saturday has found that fuel-control switches were cut, but does not explain why.