being betrayed by the leadership. he believed he didn t do anything wrong. he was a good officer. reporter: and he didn t think it would get him in trouble? he said they will kill me or they will arrest me. reporter: he was jailed for nine months. but that billionaire he d warned, berezovsky, bailed him out and helped litvinenko and his family flee to london. there litvinenko kept up the drumbeat of criticism against the russian government. he even wrote a book accusing the fsb of starting a war in chechnya for political reasons. in response, russia branded litvinenko a traitor. his image used for target practice by russian special forces.
meet andrei lugovoi. handsome, dapper, urbane. and one of the men scotland yard believes conspired to poison former russian agent alexander litvinenko. we d been negotiating an interview for weeks. he agreed, then backed out, then finally sat down with us. what did you think of litvinenko? were you friendly? would you consider yourselves friends? translator: i have always said that we have never been friends. he was a very complicated person, slightly crazy i would say. he was given to conspiracy theories, to blowing things up out of all proportion. reporter: he and litvinenko both used to work for the fsb. both had served time in jail. it was a bond between them. lugovoi had done very well in
in there without you noticing? translator: no. why don t you think the polonium may have been put there into the cup after our meeting the next day or by a guy from mi-6? he brings the polonium and pours it into the cup. that s agatha christie stuff. reporter: mi-6 is british intelligence. lugovoi says perhaps the brits killed litvinenko to embarrass russia. retired mi-6 analyst glenmore trenear-harvey says that s nonsense if for no other reason because mi-6 would never use such an expensive weapon to kill anyone. if the british wanted to kill him, then he would have fallen out of a hotel window. he would have been placed in front of a car. we d have spent $12 million in a slightly more cost-effective fashion. reporter: you would have made it look like an accident? indeed. things are done less expensively, more cost effectively. old-fashioned bullets in bodies work rather effectively and quite cheaply.
befriend litvinenko. the british wanted to find out what he knew about his former colleagues in the russian secret services. it was of great interest to us to know who these people were. so naturally, he was debriefed to talk about any of his russian contacts that came in. reporter: was he credible? oh, yes, he was. reporter: credible enough that mi-6 began paying him a monthly salary, trading information for money was one way for a former russian agent to make a living in his new home in london. then suddenly in 2006 litvinenko, who had always been fit and healthy, got very sick. it was just incredibly strong and heavy sickness, just suddenly and not stopping. reporter: litvinenko s wife marina watched him waste away in a matter of just days. oh, it was awful. his hair started to be reporter: to fall out? yes, and he started to look like a cancer patient treated by chemotherapy. i knew he was going through
them to finally determine that it was polonium versus something else. reporter: why, if he had died 12 hours earlier, would it have made any difference? because they wouldn t have found out. they would have marked the death certificate as death unknown. he would have been put in the ground, and it would have been just a mystery. unknown unknown assailants. turn the page, move on. it s the key of this murder. polonium 210 was discovered and now we know exactly sasha was killed by polonium 210. reporter: it s an almost perfect murder weapon. polonium has no smell, little taste, and without specialized equipment, it s undetectable. if you not looking particularly for polonium, you not able to discover it. do you know, it will be everywhere, but you don t know this. reporter: the amount that killed litvinenko, slipped into something he ate or drank, was no larger than a grain of salt. but that s still a thousand times the lethal dose. and that tiny bit of polonium would have