The diversion could have come from only a limited number of places. Just four facilities are licensed to handle polonium-210 in Russia: Moscow State University; Techsnabexport, the state-controlled uranium-export agency; the Federal Nuclear Center in Samara; and Nuclon, a private company. Although these licensees are monitored by the Russian government, it would not necessarily require an intelligence service to divert part of the supply into private hands. A single employee who was bribed, blackmailed, or otherwise motivated conceivably could filch a pinhead quantity of polonium-210 and smuggle it out in a glass vial (in which its alpha particles would be undetectable). Such corruption is not unknown in Russia.
Or the diversion could have come from outside Russia. A number of other countries with nuclear reactors have been suspected of clandestinely producing or buying polonium-210, including Iran (where it was detected by IAEA inspectors in 2000), North Korea (where it was detected by U.S. airborne sampling), Israel (where several scientists died from accidental leaks of it in the 1950s and 1960s), Pakistan, and China. But whatever its source, the polonium diversion has serious implications. The real problem is not its toxicity, since its alpha particles can't penetrate the surface of the skin and therefore have to be ingested or breathed in to cause any damage. (That can happen if you have polonium-210 on your person or clothes.) The more serious danger is that it could be sold to a country that wanted to set off a nuclear device, clean or dirty.
Given its value on the nuclear black market, the relationships Litvinenko had with his contaminated associates may be relevant to its origin.
To begin with, there are his contacts with Mario Scaramella. According to Scaramella, Litvinenko told him at their sushi lunch that before he had defected from Russia, his activities had included the "smuggling of nuclear material out of Russia." If true, why did the ex-KGB officer broach the subject of nuclear smuggling?
Then, there is the intriguing relationship between Litvinenko and Lugovoi. According to Lugovoi, the two former KGB officers met "12 or 13 times" in London to discuss business. Three of these meetings occurred between Oct. 15 and Nov. 1, and after each of them Lugovoi flew back to Moscow. Between the last two meetings, Litvinenko flew to Tel Aviv and Lugovoi's associate Kovtun flew to Hamburg. Trails of polonium radioactivity have so far turned up in Hamburg and Moscow. So, the purpose of these trips is part of the mystery.
Finally, there is Boris Berezovsky. Both Litvinenko and Lugovoi worked for him. Litvinenko had been on his payroll in London since his defection in 2000; Lugovoi had helped organize his security in Moscow and recruited ex-KGB men to work with him. Moreover, his London offices showed traces of polonium-210, suggesting Lugovoi and/or Litvinenko might have met with him.
The problem here is not merely catching a murderer—if indeed it was murder—but plugging a leak in the hellish diversion of polonium-210.