 One theory is he may be the murderer or an accomplice of one of the murderers of Alexander Litvinenko and mishandling the substance used, polonium-210.The Crown Prosecution Service accused Kovtun as being the second suspect of murdering Alexander Litvinenko based on the discovery of new evidence in 2011 and requested his extradition to England to stand trial in February 2012.On 22 March 2015, Kovtun appeared on "BBC News at Ten" and announced that he would testify, by video-link, to the enquiry into Litvinenko's death.