If the Kremlin is really behind Litvinenko's death, it's worth asking a big question: Why? Why would Putin approve such an aggressive and risky act on a foreign nation's soil? What had Litvinenko, a former Russian intelligence officer who was a British citizen at the time of his death, done that merited his assassination?
In the 300-plus pages of the inquiry's final report, some potential clues as to what may have lain behind Litvinenko's death can be found.
Litvinenko claimed to be revealing Russian secrets
Litvinenko had worked for the KGB during the final years of the Soviet Union, and after the Soviet Union collapsed he worked for its Russian successor, the Federal Counterintelligence Service (FSK), which was eventually reorganized into the Federal Security Service (FSB). His work largely involved investigations into criminal organizations, though he also moonlighted in security for the oligarch Boris Berezovsky. He would later claim that the FSB ordered him to kill Berezovsky, and after he went public with allegations about the FSB in November 1998, he was dismissed from the agency.
Litvinenko would later flee Russia and end up in Britain, where he set to putting his knowledge of the Russian security world to work. While in Britain he wrote books that accused the FSB of corruption.
One notable book, "Blowing Up Russia," suggested that the agency was behind a series of apartment bombings in September 1999 that had killed more than 300 people. These bombings had been blamed on Chechen separatists and were a key rationale for Russia engaging in the Second Chechen War — a war that clearly helped the popularity of Putin, prime minister at the time of the bombings. Litvinenko's book presented the argument that the bombings were a "false flag" that killed ordinary Russians for political purposes — something that would create incredible anger in Russia if ever proven.
A second book, "The Gang from the Lubyanka," accused the FSB (including Putin, the former head of the agency) of criminal acts.
These books did not necessarily conclusively prove wrongdoing by Putin or the FSB, but the inquiry notes they were considered serious investigations and clearly riled the FSB. Litvinenko would go on to make more dramatic claims in interviews, including the suggestions that the 2002 Moscow theater siege or the Beslan school hostage crisis — two highly dramatic events blamed on Islamist militant terror groups — were the work of FSB manipulation.
He was working with Putin's rivals and critics
While Litvinenko's billionaire ally Berezovsky was once a key supporter of Putin, the two had fallen out when Putin rose to become president. Facing investigation in Russia, he had fled to Britain and was granted asylum in 2003. Berezovsky became a key supporter of Litvinenko's whistleblowing projects and funded him and other Putin critics with his own sizable fortune. The inquiry's report notes that Berezovsky was often portrayed as a man who funded terrorism in Russian state media and that Litvinenko also socialized with Akhmed Zakayev, a Chechen leader who is regarded as a terrorist in Russia.
Litvinenko was linked to a number of foreign intelligence agencies while living in London. The inquiry did not find conclusive evidence on whether the Russian was working with the British intelligence agencies — the home secretary "neither confirmed nor denied" it — but it is clear the FSB believed he was. U.S. cables published by WikiLeaks have also suggested that Litvinenko may have been working with Spanish intelligence agencies.
In particular, however, the inquiry's report notes that Berezovsky's declining financial support of Litvinenko had led the former spy to look to private security work for funding. This work would often involve writing "due diligence" reports on Russian individuals and enterprises. The inquiry found evidence that Litvinenko had been asked to investigate a senior Russian politician named Victor Ivanov. Litvinenko eventually produced a report that was described as "extremely damaging," portraying the former KGB operative Ivanov as a "failure." The report is believed to have led to the breakdown of an important deal involving Ivanov.
The inquiry found some evidence that the Litvinenko's report on Ivanov may have fallen into the Kremlin's hands shortly before his assassination, though it also adds that the short timeframe makes it difficult (though not impossible) to imagine it led to the killing.
It's also worth noting that Berezovsky himself died in Britain in 2013. There was speculation of another assassination attempt — the oligarch was believed to have survived a number — but an inquest could determine a cause of death.
A personal antagonism with Putin
Another notable detail from the inquiry is what appears to be a personal side to Litvinenko's dispute with Putin. Putin himself was head of the FSB when Litvinenko tried to raise issues about the way the agency was conducting itself, and the two men are believed to have met in person. "I immediately had the impression that he is not sincere," Litvinenko would later recall in his book "The Gang from the Lubyanka." "He looked not like an FSB director, but a person who played the director."
Putin, a former KGB man himself, is believed to have viewed Litvinenko's attempts at whistleblowing as a breach of the FSB code of loyalty. This view was widely shared in the FSB, the inquiry found. After Litvinenko fled to Britain, he accused Putin of personal involvement in a whole range of criminal activities. These weren't limited to bribery or even plots like the alleged FSB apartment bombings — in July 2006, Litvinenko had accused Putin of being a pedophile and claimed that the FSB had secretly filmed him having sex with underage boys.
The inquiry's report notes that there was "undoubtedly a personal dimension to the antagonism" between Putin and Litvinenko, both due to perceived betrayal of the FSB and the allegations made about Putin himself. This could have influenced any decision by Putin to approve the assassination of Litvinenko. After Litvinenko died, Putin made a public comment that many took as an attempt to not only dispel rumors but also publicly insult the former KGB spy one last time.
“The people that have done this are not God," he told reporters on the day of Litvinenko's death (referring not to the death itself but a note Litvinenko had written accusing him of involvement), "and Mr Litvinenko is, unfortunately, not Lazarus.”