Uh, they did. And the (so far, preliminary) investigation found no military aircraft in the vicinity. But the Russians continue to vomit their "theory" on this forum.
Can you point me to the source where it can be seen that the recording of the conversation between Kiev ATC and MH17 recorded IN ATC was given to the commission?
Not the recorder from MH17 showing alleged 14 minutes radio silence from other airliners in vicinity. Preliminary report uses non-specific and rather unusual language full of weasel wording and unheard of terminology (e.g. high-energy objects). Preliminary report does not say anything. Question is why?