If those guarding an aircraft crash site are also accused of shooting the plane down, how does an international team get access to prove guilt – or innocence?
That's the essence of the international challenge in the wake of Thursday's downing of Malaysian Airlines Flight 17.
A German government statement said the two leaders "agreed that an international, independent commission under the direction of ICAO (UN's International Civil Aviation Organization) should quickly have access to the site of the accident... to shed light on the circumstances of the crash and move the victims."
Shortly thereafter the Russian foreign ministry released this statement: "The Russian side appeals to both sides of the Ukrainian conflict, urging them to do everything possible to enable access for international experts to the airplane crash area in order to take action necessary for the investigation."
But does Russia really want the truth to come out and does it have sufficient influence over the rebels in eastern Ukraine to deliver? Reporters at the MH17 crash site Saturday say pro-Russian separatists are still keeping international investigators from doing their work.
Max Seddon, a reporter for Buzzfeed tweeted Saturday:
And a couple hours later, Seddon tweeted:
At one point, a Reuters correspondent heard a senior rebel tell the OSCE delegation they could not approach the wreckage and would simply be informed in due course of an investigation conducted by the separatists. However, fighters later let them visit an area where one of the Boeing 777's two engines lay.
Without access to the site, the facts about what happened will remain murky. If the alleged perpetrators of the attack are the ones guarding the crash site and reportedly removing bodies and aircraft parts, an accurate accounting will be difficult to construct. Is that the Russian and separatists' plan?
"The terrorists, with the help of Russia, are trying to destroy evidence of international crimes," the Ukrainian government said in a statement. "The terrorists have taken 38 bodies to the morgue in Donetsk," it said.
Malaysia's Transport Minister Liow Tiong Lai appealed to the moral obligation of those who have influence over the armed men guarding the crash site.
Interfering with the scene of the crash risks undermining the investigation itself. Any actions that prevent us from learning the truth about what happened to MH17 cannot be tolerated. Failure to stop such interference would be a betrayal of the lives that were lost.
Malaysia calls for all parties to protect the integrity of the crash site, and to allow the investigation to proceed. We urge all those involved to respect the families, and the nations who have lost their sons and daughters in this attack."
Philip Hammond, Foreign Secretary of the UK, told The Telegraph Saturday: "We still can't be categoric about the cause of this terrible accident but there's a growing body of evidence which clearly suggests a missile fired from separatists in Eastern Ukraine.
Our focus now is on securing the site so there is a proper international investigation to identify the cause and the perpetrators and bring them to justice and making sure the victims are dealt with with proper dignity and respect."
Reuters reported Saturday, that Ukraine's counter intelligence chief Vitaly Naida said he had "compelling evidence" that not only had the SA-11 Buk radar-guided missile system Kiev says was used to hit the airliner been brought over the border from Russia but the three-man crew was also comprised of Russian citizens. He said the unit had returned to Russia and demanded Moscow let Kiev question them.
Could the something constructive come out of this tragedy? Could the deaths of 298 innocents create pressure for Ukraine and Russia to reach a peaceful resolution to the simmering conflict in eastern Ukraine?
"Moscow may have a last chance now to show that it really is seriously interested in a solution," Merkel's foreign minister, Frank-Walter Steinmeier told Bild am Sonntag newspaper. "Now is the moment for everyone to stop and think to themselves what might happen if we don't stop the escalation."
Merkel asked Putin during their Saturday phone call to use his influence on the separatists to reach a ceasefire in Ukraine, according to the German government.
Steinmeier's remarks echo a similar line of reasoning laid out by President Obama Friday.
"This certainly will be a wake-up call for Europe and the world that there are consequences to an escalating conflict in eastern Ukraine; that it is not going to be localized, it is not going to be contained," Obama told reporters.
The Christian Science Monitor's Peter Grier wrote: The president’s remarks, as well as statements from Defense Department briefers at the Pentagon and Ambassador Samantha Power at the UN, seemed a coordinated effort to try and use the MH 17 disaster as a means to end the fighting in Ukraine’s disputed areas, at least for the moment. In essence the US may be trying to use guilt and the shock of innocent deaths to get Moscow to rethink its strategy of keeping eastern Ukraine on a slow boil."