Bear in mind that no evidence whatsoever has been produced linking the authorities to Litvinenko's killing, and the two men who are being investigated, Kovtun and Lugovoi are both associates of Putin's most vocal critic in the UK.
But don't let the facts get in the way of a good story, it is enough just to say 'what lies behind the rash of Russian poisonings?' and point the finger at the Kremlin. In the same way, you only have to keep asking the question 'what are the links between Al Qaida and Saddam Hussein?' and eventually they will become inextricably associated in the public mind, or 'where are Saddam's weapons of mass destruction?' and his failure to answer will damn him.
On the television show Question Time, author Martin Amis was satisfied to intone that with the poisoning "here we see the asiatic side of Russia" - as if 'asiatic' was synonymous with poison. (Amis is rapidly morphing into his dad who wrote a crackpot novel Russian Hide and Seek "The scene is England 50 years after its conquest by the Soviets.")