On April Fool’s Day, I reported on two more possible additions to the long list of critics of the regime of Russian ruler Vladimir Putin who have been the recipients of violent attacks — a list I laid out in detail for Instablog readers. I only wish my report had been a springtime jest.

The member of that list whose case has been most clearly established is the famous KGB defector Alexander Litvinenko. Murdered by radioactive poison in London in late 2006, Scotland Yard has traced the toxin to Russia and accused a man closely tied to the Russian government of carrying out the hit. Russia’s response has been to refuse extradition and allow the accused to take a seat in parliament, where he is immune from Russian prosecution as well. Litvinenko had been vociferously accusing the Kremlin of complicity in the bombing of two Moscow apartment buildings in 1999, just after Vladimir Putin became prime minister — bombings Putin used to justify his immediate invasion of the breakaway province of Chechnya.

Now, the British wires are burning with news that a second KGB defector is accusing the Kremlin of trying to poison him. Colonel Oleg Gordievsky (pictured above), the highest-ranking KGB officer ever to have defected to the West (he did so in 1985 after working for three years as a double agent, taking up residence in Britain; last year, he received high decoration from the Queen in recognition of the valuable Russian secrets he passed along to Britain after his escape from the USSR). He told the Daily Mail: “I’ve known for some time that I am on the assassination list drawn up by rogue elements in Moscow. They murdered my friend Alexander Litvinenko. I have no doubt my sudden illness last November was a similar attempt on my life.”

As with the other two most recent incidents, there is not yet any clear proof of foul play. This could mean the Kremlin isn’t responsible, or it could mean that the Kremlin is cleaning up its act, not leaving behind as many traces as in the past. Gordievsky is an old man and the symptoms he complained of were stroke-like, but the doctors who examined him found no trace of any natural medical condition that could have caused them. The Kremlin, of course, was infuriated by his royal decoration, and Gordievsky has been staunchly supporting keeping the Litvinenko investigation in the public eye. A police investigation is ongoing.

A film about the Litvinenko killing is in theaters now. Director Andrei Nekrasov’s Poisoned by Polonium: The Litvinenko File details the attack and subsequent cover-up in a way that can only bring to mind the words days of the Cold War.