I rather liked the commenter who suggested that the whole thing was an exercise in performance art by the amateur painter Stone, designed to mock the NI politicians' desperate efforts to get the world's attention.
Much more depressing is the death of Alexander Litvinenko. The Viking catherd has details on polonium-210 and comments that it was "a curiously elegant and vicious assassination method". Indeed. The horror of it should be argument enough against the notion that he administered the poison to himself to discredit Vladimir Putin. Suicide-bombers, after all, go out in an instant, and self-immolation (Buddhist/Prague style) is both easier to arrange and more publicly theatrical. And where would he have laid hands on enough of the stuff? Any theory of his assassination must first climb the mount improbable of his killer having access to something found only in quantity in a nuclear reactor or linear accelerator, and in a form pure enough to be handled safely and innocuous enough to be administered easily.
Steinn points out that, at least within the US, small quantities of it are on open sale, but the amount required to kill would have cost $500,000, not to mention being a very noticeable sale. George "Dick Destiny" Smith points out that half a gram in a capsule would reach 500 degrees Celsius - "Litvinenko was cooked from the inside".
There is something about this story, though, that almost makes the suicide theory plausible - the rainswept November streetscapes of London and the doomed radioactive exile wandering towards death through the flickering mobs of Christmas shoppers. There have always been exiles and foreign secret policemen conspiring in obscure corners of the city, and Litvinenko's death is almost uncannily fitted to the genius loci. I am reminded of "The Professor", the prototype suicide bomber and proto-fascist in Conrad's Secret Agent, who carries an explosive charge triggered by a pneumatic bulb in the sleeve of his jacket, ready to blow himself up if arrested. In conversation with a comrade, he lets slip that the fuse is not instant - twenty seconds must elasp before the explosion, to the comrade's utter horror and astonishment.
But a suicide-weapon that means not seconds, but weeks of irreversible radiation sickness, is innately improbable. The Government, of course, is desperately hoping against hope that it was anyone, anyone but