New York: With search teams pulling debris and bodies from AirAsia Flight 8501 out of the Java Sea, attention now shifts to the investigation to determine what happened as the jet was heading from Surabaya, Indonesia, to Singapore.

The most important piece of evidence will be the flight-data and cockpit-voice recorders. But the wreckage and the bodies of those aboard will also provide vital clues. Here's a look at what investigators might learn.

EXTENT OF DAMAGE

If the plane came down relatively intact - possibly from a stall, pilot error or mechanical problem - the metal in the fuselage and wings would be under enormous pressure when it hit the water. Peter Goelz, a former managing director of the National Transportation Safety Board, says the wreckage would show signs of compression.

However, if the metal were torn, Goelz said, that's a sign of a breakup at altitude. The fuselage of TWA Flight 800, which exploded over the Atlantic Ocean in 1996 minutes after takeoff, was torn into many tiny pieces.

THE PASSENGERS

Some of the quickest answers could come from the deceased passengers. For instance, if a body is fully clothed, it probably emerged after the plane hit the water. If there is less clothing, the passengers might have been ejected midflight, Goelz said.

If autopsies show death came from blunt-force trauma, that "could suggest passengers were alive upon impact with the water," said Scott Hamilton, managing director of the aviation consulting firm Leeham Co. If there are other causes of death, there might have been a rapid decompression and in-flight breakup.

BLACK BOXES

The flight-data and cockpit-voice recorders are the most critical pieces of evidence. They show how fast the plane was going, how high it was, the status of all its systems and what the pilots' final words were. Accident investigators will use this information to reconstruct a timeline of what happened and why.