MH17 air crash: Battle for control of disaster inquiry
The investigation into the MH17 air disaster - in which all 298 people on board were killed - is fraught with difficulties.
The crash site is in territory controlled by pro-Russian separatists. Jurisdiction and control over what emerges as the full account of what happened will be contested fiercely. Even beyond the human tragedy, the stakes could scarcely be higher, with the future direction of the Ukraine crisis seemingly in the balance.
Who has jurisdiction?
"Responsibility for an investigation belongs to the state in which the accident or incident occurred," according to the International Civil Aviation Organization (ICAO), a UN body.
The Russia-led Interstate Aviation Committee (IAC) - the official aviation authority in Russia which counts former Soviet states, including Ukraine, as signatories to its treaty - says any inquiry should be set up under the auspices of the ICAO.
However, almost any major air crash inquiry will draw in other nations with technical expertise or better resources.
Nations with passengers aboard the doomed jet are also likely to want to play a role, or launch their own inquiries.
And the political ramifications of this disaster have already prompted a number of Western nations to call for a full, independent, international investigation.
Ukrainian Prime Minister Arseniy Yatseniuk has proposed that the Netherlands, which lost 193 of its nationals in the disaster, should lead an international investigation.
Separately on Monday, the Dutch public prosecutor's office opened a preliminary criminal probe into the crash on suspicion of murder and war crimes.
The Netherlands claims the right to prosecute suspected war criminals when the victim is Dutch, regardless of where the crime took place.
How do you investigate in a conflict zone?
Pro-Russian rebels have pledged to allow international investigators to access the crash site near the village of Grabove through a so-called humanitarian corridor.
However, monitors from the Organization for Security and Co-operation in Europe (OSCE) say they have been given only limited access to the site, with the rebels keeping them away from the wreckage.
On Monday, three Dutch investigators were allowed to the site, but it was not immediately known if they had full access.
There have also been allegations that the rebels have tampered with key evidence and reports that the whole search operation - conducted by Ukrainian emergency ministry workers and volunteers - has been chaotic.
Ukrainian officials have claimed that dozens of bodies were first taken to the rebel-controlled city of Donetsk before being moved to refrigerator wagons in the city Torez, where 251 bodies are now reportedly being stored.
The uncontrolled removal of bodies and items from the debris field could have serious implications for the integrity of the air crash investigation, experts say.
There are also already concerns over the whereabouts of the "black box" flight-data recorders.
Rebel leaders have claimed they have at least some of the aircraft's data recorders in their possession and that they will give them to international investigators.
At the same time, reports suggested that the "black boxes" could be handed over to the Moscow-based IAC.
Don't we already know what happened?
The US intelligence authorities say their monitoring systems suggest a surface-to-air missile brought down the plane, but it was not yet clear who fired it.
The two sides in Ukraine's conflict have accused each other of shooting down the jet.
Ukraine's main security agency, the SBU, released recordings purportedly of intercepted phone calls between a separatist fighter and a Russian military intelligence officer discussing the shooting down of a civilian plane minutes after MH17 crashed.
The US later said the recordings were authentic.
Meanwhile, the rebels insist their equipment is not capable of bringing down an aircraft at more than 30,000ft (9,200m) and that Ukrainian troops must be responsible.
It is alleged that a Russian-made Buk anti-aircraft missile - also known as Gadfly in Nato - brought down the plane.
Intelligence agencies will be "crawling all over" the calls and other information from the crash site, Michael Clarke of the Royal United Services Institute told the BBC.
"With what is known in the West together with these things they will probably get to the bottom of it very quickly," he said.
But he added that it was likely there would always be room for doubts.
What will investigators focus on?
Former US National Transportation Safety Board (NTSB) Chairman Deborah Hersman has said the "road map" for investigators in the first day or two would be finding all "four corners of the aircraft" - the nose, the tail and the two wing tips - as well as the flight-data recorder and the cockpit voice recorder.
Investigators would be looking to "sequence" the break up of the plane - find out where it started and how it spread, Ms Hersman told US network NBC.
The flight-data recorder will reveal the exact time of the incident and the altitude and exact position of the aircraft, while the cockpit voice recorder will show what the crew knew was happening before disaster struck.
Russian experts quoted by the Kommersant newspaper (in Russian), have been detailing what the wreckage of an plane hit by different missiles should look like.
"If this was a Buk, we should expect to see holes in the fuselage, wings etc. But if it was an air-to-air missile, then we should expect elongated 'cuts' along the body of the plane, as opposed to 'holes'."
Why are the stakes so high?
Correspondents say that if it does turn out that the Boeing 777 was shot down by the separatists - with weaponry supplied by Moscow - then it could significantly alter the terms of the whole debate surrounding the Ukraine crisis.
The disaster comes at a time of already soaring tensions.
Last week, the Ukrainian authorities accused Russia of downing a Ukrainian military transport plane on a mission over the east of the country, killing two of the eight crew members on board.
Ukraine also said one of its fighter jets - Su-25 - was shot down by a Russian plane in earlier this month.
Russia denies the accusations.