>> reporter: but they could have done a better job not spreading it all over the place if they knew. >> they also might say no, there's no way i'm going to do that. >> reporter: i don't want to handle that radioactive material? >> i am not going to kill myself in the process. >> reporter: to get closer to the truth about who killed litvinenko, we had to talk to the suspects themselves, andrei lugovoi and dmitri kovtun. in kovtun's case, it wasn't easy. a few weeks after litvinenko died of polonium poisoning, kovtun was hospitalized and lost all his hair. he hasn't been seen publicly since 2012. that left lugovoi. when we got here, he didn't want to speak with us. but on the second day of our trip he called and said he was ready to talk. coming up -- at last we lay eyes on one of the men believed to have killed litvinenko. litvinenko check your free credit scores at creditkarma. here's to progress. ...work in harmony.ody... like you, they get hungry. feed them... ...with new centrum® multigummies®