Attacks by poisoning are possibly even more common in Russia than assassinations by gunfire. Most famously, Alexander Litvinenko, a secret-police whistle-blower, was killed by polonium in London, in 2006. Last week, British newspapers reported that a Russian businessman who dropped dead while jogging in a London suburb in 2012 had been killed by a rare plant poison. He had been a key witness in a money-laundering case that had originally been exposed by the Moscow accountant Sergei Magnitsky, who was tortured to death, in 2009, in a Russian jail.