Detectives traced three distinct polonium trails in and out of London, at three different dates, which according to the investigation suggests Andrey Lugovoy and Dmitry Kovtun made two failed attempts to administer polonium to Litvinenko before the final and successful one. After the first unsuccessful murder attempt  Litvinenko, Lugovoy and Kovtun went to this sushi restaurant, where polonium-210 contamination has been found.