>> he was a law enforcement officer. >> he worked for the equivalent of the fbi. >> yeah, i mean what he was most interested in. >> in anti-corruption. >> anti-corruption is what really he was most interested in. >> his name was alexander litvinenko, sasha to his friends. but his interest in fighting corruption had made him a lot of enemies, including in his own agency, the kgb, which was renamed the fsb. litvinenko was forced to flee russia with his wife and son and seek asylum in london where he quickly caught the attention of agents of the british intelligence service mi-6. glenmore trenear harvey was a retired and very charming mi-6 analyst who was asked to befriend litvinenko. the british wanted to find out what he knew about his former colleagues in the russian secret services. >> was he credible? >> oh, yes, he was. >> reporter: credible enough