‘It is too early to say whether those responsible for Alexander Litvinenko’s end intended its cause to be discovered,’ I wrote in the LRB nine years ago. ‘A lingering death caused by a painful poison unknown to science sends out a powerful message.’ The evidence presented to Sir Robert Owen’s Public Inquiry Report, published on 21 January, is clear. The plotters of Litvinenko’s death intended its cause to remain a mystery. The closing statement of the Metropolitan Police Service to the inquiry says:

it is clear that polonium would not have been identified through the normal post mortem toxicological process. Polonium was the almost perfect murder weapon – we use the past tense because it no longer has that accolade – as a result of this investigation it has lost its anonymity for ever and will now be first on a pathologist’s check list if ever a Russian dissident dies in similar circumstances.

Radiation poisoning did not emerge as a likely cause of Litvinenko’s illness until two days before his death. His wife had raised the possibility of poisoning early in his three-week illness. Thallium intoxication was strongly suspected. But some of its typical features were missing and his total bone marrow failure didn’t fit. On 21 November an eminent toxicologist was interviewed on TV. He suggested that the thallium might have been radioactive. A detective saw the interview and mentioned it to the senior investigating police officer, who had blood and urine samples sent to the Atomic Weapons Establishment. A spike of polonium-210 was found in the urine. It was thought to be an anomaly, and an unlikely cause. Another urine test was done. It arrived at AWE on 23 November. Polonium-210 contamination was confirmed in the afternoon; Litvinenko had a cardiac arrest at 8.51 p.m., and was declared dead at 9.21. The Met concluded that he survived longer than the masters behind his murderers expected; although doomed because of the lethal dose, he was young and fit, and got top quality medical care in hospital. They very nearly got away with it.

I was right to speculate that the likeliest poison vector would be food or drink, but wrong in suggesting that the polonium would be coated and camouflaged as grains of salt or crystals of brown sugar. The police investigation, Operation Whimbrel, determined that the lethal dose was in a cup of green tea with lemon and honey, poured from a white porcelain teapot, and drunk without sugar. The polonium had been put in the pot by Andrey Lugovoy and Dmitri Kovtun. They left a polonium trail wherever they went. But as the Met said in their closing statement, they ‘were not bungling assassins’ but

simply ignorant of the true qualities of the poison they carried and we suggest that ignorance was essential for those engaged to administer it covertly... their masters would not have been unduly concerned about the polonium trail because they would not have expected the cause of death to be discovered.

Owen’s Inquiry finished on time and within budget (it cost £2,249,381) in spite of his team getting, as he says, ‘silkier and silkier’, starting with two junior counsel but finishing with three QCs. Against most people’s expectations, he concluded that the poisoning operation was probably approved by President Putin. The evidence is circumstantial only, but Putin is a Chekist, and proud of it. The Cheka was the forerunner of the OGPU, the NKVD (which masterminded the assassination of Trotsky), the KGB and the FSB. Ice picks in the head are too blatant. My guess is that the search is probably on for a polonium-210 successor. Ricin is out because it would be suspected. But its mode of delivery, in a little pellet shot from an umbrella, would do nicely for other lethal poisons. If a rapid death is wanted, consideration would probably be given to puffer fish tetrodotoxin. For a slow and painful death, some exotic snake venoms would do nicely. They would be harder to detect in the UK than polonium-210.