I know Putin is above the law. Still the only evidence we got is that he has all appearances against him. Yes, a motive has has, the victim was a political enemy. And most of all, he has the opportunity. Nobody can sue him (at least not by national law, and Russia doesn't recognize international law). And of course, the pattern. I lost track of counting how many of Putin's opposers ended up either dead, in very bad health conditions or in jail for tax fraud. May not irrefutably prove Putin is behind it, but the pattern is uncanny.
I don't know about the U.S. news channels, but here in the Netherlands the news is pretty full of it. Now honesty requires me to say that the Netherlands and Russia have been on very bad terms since the MH17 incident and Russia denying all its involvement, (not to mention that Russia showed nerve by accusing the NL of spying less than a year after they were caught in action themselves while spying at an international complex in the NL) but still, things look very clear here...