Interpol has already joined the investigation into the killing of former Russian agent Alexander Litvinenko, the Interfax news agency reported Tuesday. The head of the Russian Interpol National Central Bureau, Timur Lakhonin, told reporters that "considering that law enforcement agencies of different countries are handling this, Interpol and its possibilities are certainly being used". "Interpol has already been engaged for the operative exchange of information between different countries," Lakhonin said. The death of the 43-year-old former KGB colonel at the end of November has been linked to the discovery of polonium-210 in his body.