Litvinenko had co-written a book in which he blamed former FSB superiors of carrying out bombings of Russian apartment buildings in 1999 that were blamed on Chechen militants.
He also accused Putin of being behind the 2006 contract-style slaying of Anna Politkovskaya, a journalist who exposed human rights abuses in Chechnya.
Owen said the method of killing, with radioactive poison, fit with the deaths of several other opponents of Putin and his government, and noted that Putin had “supported and protected” Lugovoi since the killing, even awarding him a medal for service to the nation.
“I am sure that Mr. Lugovoi and Mr. Kovtun placed the polonium-210 in the teapot at the Pine Bar on 1 November 2006,” he wrote — probably under the direction of the FSB.
He said the operation to kill Litvinenko was “probably” approved by then-FSB head Nikolai Patrushev, now head of Putin’s security council.
He said it was “likely” the FSB chief would have sought Putin’s approval for an operation to kill Litvinenko.
Marina Litvinenko, the spy’s widow, said she was “very pleased that the words my husband spoke on his deathbed when he accused Mr. Putin have been proved by an English court.”
She urged Cameron to expel Russian intelligence agents operating in Britain and impose economic sanctions and travel bans on Putin and other officials linked to what her lawyer, Ben Emmerson, called “a mini-act of nuclear terrorism on the streets of London.”
“It’s unthinkable that the prime minister would do nothing in the face of the damning findings,” Marina Litvinenko told reporters.
Britain’s scope for strong action is limited, however.
U.K.-Russian relations have remained chilly since the killing of Litvinenko, who was granted British citizenship shortly before his death, and worsened with Russia’s involvement in the separatist fighting in Ukraine. But the inquiry’s report comes as the two countries are cautiously trying to work together against the Islamic State group in Syria, and neither wants a major new rift.
May, the home secretary, announced asset freezes against Lugovoi and Kovtun, and said Interpol had issued notices calling for their arrest if they traveled abroad. Russia refuses to extradite them.
Lugovoi is now a member of the Russian parliament, which means he is immune from prosecution in his country. In an interview with The Associated Press, he called the British investigation a “spectacle.”
“I think that — yet again — Great Britain has shown that anything that involves their political interests, they’ll make a top priority,” he said.