1. LitvinenkoIt is hard to keep track of all the people and places where polonium 210 may have been found. For example, we should not forget Litvinenko's wife, who presumably got contaminated by Litvinenko rather than by Lugovoi. There is also that strange fellow Mario Scaramella -- another ex-KGB agent --, who met with Litvinenko in the Itsu sushi bar.
2. Two or three airplanes that flew between Moscow and the UK, airplanes on which the possible assassin traveled
3. British embassy in Moscow, which the possible assassin visited
4. Millennium Hotel in Mayfair, London, where the possible killer Lugovoi, or Lugovoy, met with Litvinenko and Litvinenko's friend or associate, Dmitry Kovtun
5. Sushi bar Itsu, where Litvinenko met with Mario Scaramella, on the same day (before or or after?) Ltivinenko met with Lugovoi
6. Dmitry Kovtun, who himself now lies in a coma
7. Six or seven staff members of the bar in the Millennium Hotel
Of course, it may turn out that all of these people worked at a nuclear power plant on the side -- or perhaps they had the hobby of collecting anti-static brushes (some of which carry small amounts of polonium 210).
Or perhaps the waiter did it!
Does Lugovoi live near Chernobyl? Does he meet with former KGB agents to trade stories about the good old days and exchange souvenirs of the tools of the KGB trade?