Boeing engineers in Russia could help
Here's a suggestion. Boeing has a subsidiary in Moscow, “Boeing — Russia” with over 2,000 Russian engineers. How about if a Boeing team from Moscow, headed by the President of Boeing/Russia, was sent to the crash site to investigate the cause? I'll bet a few of these Russian aerospace engineers are well-versed in the capabilities of ground to air missiles. As ethnic Russians, they should have no difficulty entering this volatile area of Eastern Ukraine and would be heartily welcomed by the rebels.
Their Boeing report would be objective and unbiased, in line with Putin's latest statements.