On Tuesday the Netherlands will publish its final report on what happened to Malaysia Airlines flight MH17, which crashed in Ukraine in July last year, killing all 298 people on board.
Thirty-eight Australians were among the dead.
Governments and relatives of victims are waiting for the report because it could point out who was responsible for the plane's destruction during a flight from Amsterdam to Kuala Lumpur.
So far, the Netherlands has avoided committing itself to any theory.
Look back on the key issues in the crash ahead of the report's release.
Was it shot down?
Ukraine and Western countries have long-suspected flight MH17 was brought down by a ground-to-air missile fired by Russian-backed rebels.
However, Moscow denied that accusation, blaming the crash on an unidentified Ukrainian fighter jet and a Ukrainian-launched anti-aircraft missile.
Military analysts say a medium-range surface-to-air missile is the weapon most likely used to shoot down the passenger airliner, most likely the Buk or variants used by both Russian and Ukrainian forces.
Another scenario for the downed airliner could involve an air-to-air missile launched from a fighter jet, though there has been no indication of a warplane nearby at the same time.
How did the plane crash?
Witnesses captured footage of the downed plane crashing in Ukraine. A fireball and smoke can be seen in the distance.
In another video, debris is shown falling from the sky as a massive plume of smoke rises.
Who were the Australian victims?
Who said what?
These were innocent people going about their lives and they have been wantonly killed by Russian-backed rebels, quite possibly, maybe probably using Russian-supplied equipment.
This tragedy would not have happened if there were peace on this land ... And certainly, the government over whose territory it occurred is responsible for this terrible tragedy.
MH17 is not an incident or catastrophe, it is a terrorist attack.
If it transpires that the plane was indeed shot down, we insist that the perpetrators must swiftly be brought to justice.
What can we expect from the report?
In its preliminary report released two months after the crash, the Dutch Safety Board said the plane probably broke up in the air after being hit by "high-energy objects" from outside.
It also said there were no indications technical fault or crew actions were to blame for the crash.
In July this year, Russia vetoed a proposal for a United Nations-backed tribunal to investigate and prosecute whoever was responsible for the crash.
The proposal had been put forward by Malaysia, backed by the Netherlands, Ukraine and Australia, who believed an international tribunal would have the legitimacy needed to demand the extradition of alleged perpetrators from any country harbouring them.
The Netherlands has since said affected countries are pursuing alternative routes to prosecution.
ABC/wires
