You are correct, that the evidence is rather flimsy. Hence, my decision that we need conclusive evidence. All we have is an accumulation of circumstantial evidence so far, and that provided by "our side" is no better than that provided by "their side".
But, in all of this, I keep coming back to the fact that a president was deposed, and another president installed - that president largely relying on some "irregular" forces who keep order in the realm. And, everywhere you look, are western investors who have financial interest in the region.
I remain quite suspicious of Kiev - although I'm not yet willing to state anything like "Kiev did it in an attempt to gain world support for a genocidal campaign in the east of the country." Not willing to commit myself to such a statement yet, but I'm leaning that way.