All the more reason to check out the Ukrainian missile batteries isn't it?
Assuming you really want to find out who did this...
We have been monitoring that area with our intelligence satellite technology for months. We know exactly where the missile was fired from and NSA has all of the ground communications directing it. We probably shared some of it with the Brits hence the British UN Rep's remarks.
For whatever reason, we don't want to share that information with the public. Perhaps we are using it as leverage against Putin to pressure him into doing something helpful re the Iranian talks or in other areas.