Updated

A former African judge who has reviewed new information on the mysterious 1961 plane crash that killed U.N. Secretary-General Dag Hammarskjold says "it is plausible that an external attack or threat may have been a cause of the crash."

Former Tanzanian Chief Justice Mohamed Chande Othman says in a report released Wednesday that it also remains conceivable that the crash in Congo resulted from pilot error. He says the possibility of sabotage is also still being investigated.

But despite progress in finding the truth of what happened, Othman says further investigation is needed to finally establish the facts.

He says it is almost certain that Hammarskjold and members of his party were not assassinated after landing and that all passengers died from injuries during the crash, instantaneously or soon after.