the russian mobsters he was investigating. perhaps someone who thought he was a traitor for working with british intelligence. since november 2006 litvinenko s widow marina has been asking how big was the conspiracy? who was behind it? s h how high did it go? dangerous questions, as she knows better than anyone. you think you play chess, but they play russian roulette. reporter: those who were closest to litvinenko believe the kill order may have come e from the very top because rd litvinenko picked a fight with the wrong person from his past. none other than russian president vladimir putin. sasha was on a mission. he was trying to prove that putin is as corrupt as anybody in post-communist russia. reporter: the mission may have started years before when litvinenko made that flow chart of corruption in the fsb.
originally called a suicide, last year a judge said he couldn t rule out murder.ul the way he killed himself reporter: he hanged himself with a scarf. with a scarf, in the bathroom, and the fact that his bodyguard was not there, it lfsc raises questions. reporter: in february, 2015,5 another putin opponent, boris ti nemtsov, was gunned down in the shadow of the kremlin. several suspects have been arrested, and the office of the president has denied involvement. the victim was about to lead a major rally against putin. it went on without him. people shouldn t be killed because theyt happen to disagr with the government.
the head of the agency at the time was putin. after litvinenko fled to london, and putin became president of russia, litvinenko attacked him relentlessly and by name. i and others said that this is a very dangerous thing to do because you re you re personalizing this. reporter: you told him that? yes. reporter: but marina and others believe the ultimate motive may not have been personal at all, rather, it was all about money. we learned that in 2005 and 2006 litvinenko made multiple visits to spain helping prosecutors take down a major organized crime ring. one that litvinenko publicly claimed had financial ties to president putin. putin s office has never responded to that allegation. anne applebaum, a pulitzer prize winning author and expert on russia ri i think anything that litvinenko was doing that came close to the source of putin s
awful realization that he had been the victim of a political assassination by agents of the russian state. reporter: an expert witness testified the polonium that killed litvinenko could have ss only come from russia. and in 2015 putin gave lugovoi a medal, the order of merit to the fatherland, second class, for his work in the duma. you think russia will ever come clean and this will be known? i believe one day we will know this. it will be very obvious for people to decide.er reporter: in the years she s been looking for answers, otherf questions have multiplied, other deaths have been recorded. there was boris berezovsky the russian oligarch litvinenko saie he refused to assassinate. another prominent critic of putin. in 2013, he was found dead in his london home.wa