andrei lugovoi and dmitry kovtun. in kovtun's case, it was an easy.tun was hospitalized and lost all his here. he hasn't been seen publicly since 2012. that left lugovoi. when we got here, he didn't want to speak to us. but on the second day of our trip, he called and said he was ready to talk. >> coming up -- we ask the question the world wants answered. >> did you put polonium in the tea? >> when "dateline" continues. >> meet andrei lugovoi. one of the men scotland yard believes conspire to poison former agent alexander litvinenko. we've been negotiating an conspired to interview for weeks. poison he agreed, then backed out, alexander litvinenko. we had then finally, sat down with been negotiating an interview for us. weeks. , we what did you think of agreed, then backed, litvinenko? out then finally sat down with us. >> what did you think? were you friendly. were would you consider yourself you friendly? france? did you consider yourselves friends? >> >> i have always said that we i have always have never been friends. said that he was a very compl

reactor of the fourth unit of the nuclear power plant, deputy chairman of the kgb about the ussr kovtunording to the official version, which subsequently or the head of the basis of the criminal case , the plant personnel conducted a planned experiment at the fourth unit, which, according to the plan, was supposed to increase the safety of the nuclear power plant of change, they say that this experiment is to blame. at the same time, the program of the experiment, which was going to be carried out for the fourth time, was not agreed with the security department. and more importantly, with the designers of the reactor, the reactor is designed as a is the norms and rules of the station is designed. if we omit the technical details, the picture will turn out to be a simple reactor of the type that was installed at the chernobyl plant has a number of design features and the personnel should not have known. true reasons this tragedy is a serious constructive and shortcomings of the apparatus itself, that is, the protein-1000 reactor, as well as the control and protection system of this react