A British inquiry into the 2006 death of Russian dissident Alexander Litvinenko led by retired judge Sir Robert Owen has concluded that Russian President Vladimir Putin very likely the ordered his assassination. Litvinenko died of poisoning as a result of drinking polonium 210 which was slipped into his tea in a London hotel room.
Let's just say you can't buy polonium 210 at the Boot's drug store down the road from Westminster.
Litvinenko was a former FSB (Federal Security Service) agent who broke from the group when he accused his superiors of ordering the assassination of Russian businessman Boris Berezovsky in 1998. Berezovsky later died under suspicious circumstances in Britain in 2013. While in exile in London, Litvinenko wrote two books about the inner workings of the FSB and their efforts to bring Putin to power. But what probably sealed his fate was his allegation in October 2006 that Putin ordered the assassination of journalist Anna Politkovskaya. A month later, Litvinenko would be dead.