Andrei Lugovoi
On November 1, 2006, Alexander Litvinenko, a former lieutenant colonel of the Russian FSB who had defected to the UK and become a vocal Kremlin critic, met two former Russian intelligence contacts—Andrei Lugovoi and Dmitri Kovtun—at the Millennium Hotel in London. UK Crown Prosecution Service charges Lugovoi with murder; Russia refuses extradition.
If you're learning about this topic for the first time, these are the best places to continue — documented evidence and historical relationships are the guide.
Andrei Lugovoi is documented in the evidence record of this published dossier.

Co-documented with Andrei Lugovoi in 1 published dossier, including “The Litvinenko Poisoning”.
Co-documented with Andrei Lugovoi in 1 published dossier, including “The Litvinenko Poisoning”.