Ten years after former Russian intelligence officer Aleksandr Litvinenko succumbed to a fatal dose of radioactive polonium in London, his wife lives with the pain of knowing his killers may never be brought to trial.
The only justice Marina Litvinenko has seen is a British public inquiry that concluded in January this year that there was a "strong probability" that her husband's assassination was carried out by Russia's Federal Security Service (FSB), and "probably" with the approval of President Vladimir Putin. Moscow, however, calls the inquiry "politicized" and has said the alleged killers -- who escaped safely to Russia -- will never be extradited to Britain.
Marina recently told Current Time TV that she takes consolation in memories of the happy times she and her husband initially enjoyed after they received political asylum in Britain in 2000. Marina told the Russian-language media outlet, run jointly by RFE/RL and VOA, that she and Aleksandr particularly loved visiting the gardens of Kensington Park.
"When we saw that squirrels run right up to you, we realized that we were in some kind of fairy-tale kingdom," she recalls. "Sasha [Aleksandr] always joked that we were in a kingdom, under the protection of a queen, on an island, and he was glad that he had brought us here and that we were safe.... Unfortunately, things didn't turn out that way."
WATCH: Marina Litvinenko: We Were Safe In A Fairy-Tale Kingdom
They had fled to London after Litvinenko, a former FSB officer, publicly spoke in 1998 about the spy agency's links to organized crime and revealed he had been asked by his superiors to kill Russian tycoon Boris Berezovsky the year before. He spent nine months in jail after breaking the FSB's code of silence and then was released on acquittal. Berezovsky, who acquired great wealth after the breakup of the Soviet Union, fell afoul of Putin after the latter's rise to the presidency, and would go into exile in London himself in 2000.
In London, Litvinenko became a British citizen and an outspoken critic of the Kremlin. He wrote a book in which he claimed FSB agents instigated the bombing of apartment blocks in Moscow and two other cities in 1999 in order to blame them on Chechen rebels and strengthen the case for a second invasion of Chechnya. He also had good relations with Russian journalist Anna Politkovskaya, who was investigating human rights abuses by the Russian military in Chechnya and would herself be assassinated in Moscow in 2006.
But perhaps equally annoying to the Kremlin, Litvinenko was working as a consultant to Britain's intelligence agency MI6. He also was working separately as a security adviser to Berezovsky, who would die under mysterious circumstances in his home in England in 2013.
According to evidence presented at the inquiry, there were two attempts to assassinate Litvinenko, both using polonium-210, a rare radioactive isotope. The first attempt, on October 16, 2006, apparently failed due to an insufficient dosage. The second attempt, in which his alleged assassins Andrei Lugovoi and Dmitry Kovtun gave him poisoned tea during a meeting at a bar in a central London hotel on November 1 the same year, succeeded. Three weeks later, Litvinenko died in a London hospital at age 44.
Lugovoi, a former FSB agent who is today a member of the State Duma, and Kovtun, a former KGB agent, returned to Russia and remain there today, far from the reach of British authorities. Moscow has both refused British extradition requests and denied any involvement in Litvinenko's death, as have Lugovoi and Kovtun.
Many mysteries still surround the case.
One is why Litvinenko drank tea with his alleged killers, one of whom -- Lugovoi -- he first met in Russia in the 1990s.
One of Litvinenko's friends, former Chechen politician Akhmad Zakayev, told RFE/RL that he finds the meeting all the stranger because Litvinenko knew he was in constant danger of being assassinated. Zakayev, the leader of Chechnya's government in exile in London, recalls that Litvinenko once told him that "if someone wants to eliminate you, he will send you a person from your past."
Mysterious, too, are the words Putin spoke when journalists asked for his reaction shortly after Litvinenko's death. Putin answered: "The people who did this are not the Lord Almighty and Mr. Litvinenko is unfortunately not Lazarus."
Marina has thought much about those words because of a quote she found in her husband's diary. He had written: "When Lazarus rose from the dead, no one asked him any questions. It is necessary to respect the silence of the dead."
What both men meant by their separate references to the biblical parable of Lazarus is unknown.
WATCH: Putin, Litvinenko, And Lazarus
For five years after his death, Marina grieved silently. But in 2011 she filed a lawsuit demanding a public inquiry in Britain.
"I did what I had to do as a normal loving wife who lost her husband," she says today. "Someone killed a person, and I have the right to know who killed him. It's not my fault that Putin's name is in the inquiry conclusion."
That the Russian state could have carried out an assassination in the heart of the British capital using radioactive materials continues to shock many observers in London, who say the reaction of the British authorities to the killing should have been stronger.
"I think we were too soft on Russia at the time," says Edward Lucas, a senior editor with The Economist. "I believe that the British government tried to play down the importance of the fact that in our country there was an act of ... terrorism which not only killed Mr. Litvinenko but jeopardized the lives of hundreds of others who walked the streets of London."
London initially reacted by expelling Russian diplomats, limiting visas for Russian officials, and virtually ending cooperation between the countries' intelligence services in 2007. But by 2010, relations warmed again and in 2012 Putin visited the British capital as Russia competed in the London Olympics. Since then, relations have since been thrown into turmoil again by Russia's annexation of Ukraine's Crimean Peninsula in 2014 and the ensuing sanctions imposed on Moscow by the West.