Please remember, polonium isn't a GIANT nuclear facility red flag -- a tiny amount is sputtered onto gold foil, and is in the back of many laboratory balances, the alpha emission functions to mitigate static charge.
I knew something radioactive was there, but I didn't know the choice was polonium. When I'd heard it, and people also mentioned Litvienko's poisoning, I said, "How about that. Marie Curie finally got one."
For those of you not up on chemistry trivia, Marie Curie, physicist for France, was Maria Skłodowska, and she named the element she discovered Polonium for her homeland Poland, at that time under domination by Tsarist Russia. A real pre-WWI scandal, politicizing the periodic table, like that.
In fact some people, likely Putin apologists, point out that anyone could have scraped off a bunch of static blockers, and fed his tea -- rival spy agencies, disgruntled oligarchs, random serial killer -- or, you know, the obvious likely culprit.
Whenever I see a laboratory balance, missing its foil in the holder, I like to ask, "who paid you to take out whom?" Currently, one is half corroded -- I don't even know how to explain that, unless its not gold foil for some reason.