It was in 2004 when they were in the news for trying to poison the Presidential candidate of Ukraine Viktor Yushchenko with another inconspicuous compound called dioxin. If you're going to Knock people off, at least pick something that is generic and off the shelf, not something like "POLONIUM" 209 or dioxin.
http://en.wikipedia.org/wiki/Polonium
Sure, lets go to the supermarket and buy some "POLONIUM". Give me a break; even a sudden break failure on a car like from some cheap Hollywood 60s flick would be more believable!
http://en.wikipedia.org/wiki/Dioxin
The Ukraine issue for those living under a rock:
http://news.bbc.co.uk/2/hi/europe/4088345.stm
http://www.msnbc.msn.com/id/6697752
Truth is, the Russians were notorious for using "contact poisons to eliminate people all through the Cold War.
Along with those seeking to overthrow the Russian government, the term is also applied to "those causing mass disturbances, committing hooliganism or acts of vandalism".
Much more controversially, the law also defines "those slandering the individual occupying the post of president of the Russian Federation" as extremists.