Analysing the aircraft's "black boxes" - the cockpit voice recorder and the flight data recorder, both of which have been found - will help investigators determine what caused it to suddenly plummet from the sky.
No hard evidence has emerged to suggest that a bomb on board the plane caused the crash - and there are questions about how a would-be bomber would evade heightened security measures around Sharm el Sheikh airport - but one expert told the BBC that descriptions of the wreckage indicate that such an event remains a possibility.
Professor Michael Clarke, Director General of the Royal United Services Institute think-tank said: "Early reports said that [the aircraft] split into two and that suggests a catastrophic failure, not a mechanical failure, but that suggests perhaps an explosion on board.
"So I'd be much more inclined to think if we have to guess at this stage, it's much more likely to have been a bomb on board rather than a missile fired from the ground."
Again, analysis of the main wreckage site and the debris field will enable investigators to evaluate this theory.