Poisons have been used by humans to rid the world of unwanted spouses,
enemies, and political opponents for at least 6500 years, writes Andrew Rankine.
Until the recent cases of Litvinenko (Po210) and Markov (ricin), one
might have suspected that poisoning was going out of fashion.
Certainly, the bullet or the bomb represent a clearer statement, but
the stealthy poison surely does have a certain élan.