Human Rights Voices

LONDON - In the dank, dark days of November 2006, as Alexander V. Litvinenko, a former K.G.B. officer turned foe of the Kremlin, lay dying in a London hospital, he and his associates composed a deathbed missive to President Vladimir V. Putin.

In the letter, Mr. Litvinenko said he could hear "the beating of wings of the angel of death" and blamed Mr. Putin for his plight. But, he told the Russian leader, "the howl of protest from around the world will reverberate, Mr. Putin, in your ears for the rest of your life."

The echo could be heard Thursday with the release of the final report of a lengthy public inquiry into Mr. Litvinenko's death. It was probable, said the report, by a retired judge, Sir Robert Owen, that Mr. Putin and his spy chief at the time, Nikolai Patrushev, had approved an operation to kill Mr. Litvinenko, using a highly toxic and rare isotope, polonium 210.

"Strong circumstantial evidence of Russian state responsibility," the judge wrote, had led him to the conclusion that Mr. Litvinenko was indeed poisoned when he met Andrei K. Lugovoi, a former K.G.B bodyguard, and Dmitri V. Kovtun, a Red Army deserter, for tea in the Pine Bar of the Millennium Hotel in London on Nov. 1, 2006.

The polonium that was used to poison Mr. Litvinenko, the judge said, had probably come from a Russian reactor, and he said there were "powerful motives for organizations and individuals within the Russian state to take action" against the former K.G.B. officer.

Though Sir Robert's 328-page report, more than nine years after the poisoning, cited no hard evidence that Mr. Putin or Mr. Patrushev had been aware of the plot to kill Mr. Litvinenko or had sanctioned it, the conclusions were the most damning official links between Mr. Litvinenko's death and the highest levels of the Kremlin.

"Taking full account of all the evidence and analysis available to me," Sir Robert said in the report, referring to the Russian security service, "I find that the F.S.B. operation to kill Mr. Litvinenko was probably approved by Mr. Patrushev and also by President Putin."

The report was more emphatic when it came to how Mr. Litvinenko died.

"I am sure that Mr. Lugovoi and Mr. Kovtun placed the polonium 210 in the teapot at the Pine Bar," the report said. "I am sure that Mr. Lugovoi and Mr. Kovtun were acting on behalf of others when they poisoned Mr. Litvinenko."

Sir Robert based his conclusions on public testimony from 64 witnesses and secret evidence in closed hearings, placing an imprimatur on what had been previously dismissed in Russia as speculation.

Sir Robert on Thursday listed various possible motives for Mr. Litvinenko's assassination, including a belief among Russian security officials that the former officer had betrayed the F.S.B. and had begun to work for British intelligence after he fled to Britain in 2000. Mr. Litvinenko was also a close associate of prominent opponents of the Kremlin based in London, including Boris A. Berezovsky, a former oligarch and enemy of Mr. Putin's who died in 2013, the report said.

Mr. Putin and Mr. Litvinenko, both veterans of the K.G.B., served in its successor agency, the F.S.B., or Federal Security Service, with Mr. Putin going on to lead that intelligence agency.

"There was undoubtedly a personal dimension to the antagonism between Mr. Litvinenko on one hand and President Putin on the other," Sir Robert wrote in his report.

As the deathbed letter, read to journalists, had forecast, the "howl of protest" arose anew on Thursday, with Mr. Litvinenko's widow, Marina, demanding the expulsion of Russian spies from Britain and targeted economic sanctions against Mr. Patrushev and Mr. Putin. Sitting beside her at a news conference, Marina Litvinenko's lawyer, Ben Emmerson, said it would be "craven" of Prime Minister David Cameron to fail to respond to what he called "nuclear terrorism" on the streets of London.

In Parliament, the home secretary, Theresa May, called Mr. Litvinenko's death "a blatant and unacceptable breach of the most fundamental tenets of international law and of civilized behavior," while also noting that it "does not come as a surprise" that Russia apparently had a role. She said the British assets of Mr. Lugovoi and Mr. Kovtun would be frozen, although she did not say how valuable those assets were. Ms. May also said the Russian ambassador would be summoned to be told of Britain's response.

For all that, officials indicated that Britain was not likely to do anything that would plunge relations into an icy chill similar to what occurred after Mr. Litvinenko's death in 2006.

Russia on Thursday responded to the judge's report, calling the inquiry politicized and saying it was not public at all.

"We regret that the strictly criminal case has been politicized and has darkened the general atmosphere of bilateral relations," said Maria Zakharova, a Russian Foreign Ministry spokeswoman in Moscow, the Russian news agency Interfax reported.

Mr. Lugovoi, now a member of Parliament in Russia and the recipient of a medal from Mr. Putin, said the accusation that he had poisoned Mr. Litvinenko was "absurd," Interfax reported, and a Kremlin spokesman, Dmitri S. Peskov, said the Litvinenko case "is not among the topics that interest us."

The British police have accused Mr. Lugovoi and Mr. Kovtun of murder, charges they deny, and Russia has refused to extradite them, saying such a move is banned by its Constitution.

The authorities in Britain have said traces of the isotope left by the two men created a so-called polonium trail for investigators to follow once scientists had identified the toxic substance used to poison Mr. Litvinenko. The trail led through airplane seats and hotel rooms, offices and restaurants, even a soccer stadium.

Sir Robert wrote in his report that he believed that the two men knew they were using a deadly poison, but he suggested that they might not have been aware "precisely what the chemical that they were handling was, or the nature of all its properties."

The inquiry, which began almost a year before the final report was released, had been initiated after dogged efforts by Ms. Litvinenko to press for a full accounting of her husband's death.