Litvinenko, a former Russian intelligence officer turned fierce Kremlin critic, died in 2006 after drinking tea poisoned with the radioactive isotope polonium-210 at a London hotel. His family says he was working for Britain's intelligence services, and believes the Russian state was behind his death.
Britain has named Andrei Lugovoi, a former KGB officer and Russian lawmaker, and businessman Dmitry Kovtun, who met Litvinenko hours before he fell ill, as the main suspects. Both deny their involvement and have refused to attend the inquest, though they have sent legal representatives. Russia has turned down British requests to extradite the two men.
In Britain, inquests are held to determine the facts whenever someone dies violently, unexpectedly or in disputed circumstances, though they do not apportion blame. But in Litvinenko's case every detail of the inquiry is being scrutinized for clues to the alleged involvement of Russia's secret services.
Parts of the inquest have been held in secret after the British government cited security reasons, over the objections of Litvinenko's family and media. Russia's top investigative agency has conducted its own investigation of the crime and said that Lugovoi, who claims he was also exposed to the polonium, was also a victim.
Lugovoi claimed the polonium trail in fact led from London to Moscow and scoffed at allegations in the British media that the Russian state ordered Litvinenko's death.
"Litvinenko's not Trotsky - he doesn't have enough stature for secret services to run around the whole world after him with an icepick in their hand," he added, referring to the prominent rival of Stalin assassinated in Mexico in 1940.
Brandishing what he said was a classified British police report into Litvinenko's death, Lugovoi said that the accusations against him were "nonsense" and that Scotland Yard was ignoring alternative theories of the crime in order to smear the Kremlin.
Litvinenko's alleged work for British intelligence, collaboration with Spanish authorities investigating the Russian mafia and private intelligence work was a "lifestyle that earned him all sorts of open and covert enemies," Lugovoi said.
Logovoi alleged that the British inquest has been influenced by Boris Berezovsky, a flamboyant and outspoken Russian oligarch in London exile who had close ties to Litvinenko. Lugovoi says Berezovsky was involved in the poisoning, a charge that Berezosvky has denied.