Whence the polonium-210?

The death of former KGB spy and Putin critic Alexander Litvinenko through poisoning by the exotic nuclear material polonium-210 has occasioned a good deal of outrage and a mad scramble to try to track down possible suspects. Vladimir Putin's government is a prime suspect, of course, though there may be reasons to doubt that and there are plenty of unsavory characters in the Russian underworld who might have a motive.

In this article, however, longtime watcher of things clandestine Edward Jay Epstein argues that the most important thing is to try to track down where the polonium-210 came from -- which will probably help in identifying who did it. But a leak of polonium is troubling for this reason:

"If a rogue nation (or terrorist group) obtained access to any quantity of polonium -- even, say, a half gram -- it could use it as in initiator for setting off the chain reaction in a crude nuclear bomb. With a fissile fuel, such as U-235, and beryllium (which is mixed in layers with the polonium-210), someone could make a "poor man's" nuke. Even lacking these other ingredients, the polonium-210, which aerosolizes at about 130 degrees Fahrenheit, could be used with a conventional explosive, like dynamite, to make a dirty bomb."

Epstein tracks what is known about where traces of polonium-210 have shown up to offer a guide for investigators and interested observers.