Interpol has joined the investigation into the killing of former Russian agent Alexander Litvinenko, Russian news agencies reported Tuesday.
"Cooperation through Interpol channels has already started, as several countries are involved in this case," said Timur Lakhonin, the head of Interpol's Russia division, according to the RIA-Novosti news agency.
The investigation so far has pulled in witnesses in three countries: Britain, where Litvinenko fell sick and died after being poisoned with polonium-210, Russia and Germany. Some of the men who met with Litvinenko on Nov. 1 the day he is believed to have fallen ill traveled to London from Moscow and Hamburg.
The involvement of Interpol, the largest international police organization, should ease the way for investigators in each country to obtain evidence and testimony. Interpol, which has 186 member nations, coordinates cross-border police cooperation, reports AP.
British investigators on Monday questioned Andrei Lugovoi, a key witness in the killing, in the Moscow hospital where he was undergoing radiation checks, Russian news reports said. Lugovoi told the agencies that he had been questioned for three hours.
"I gave testimony exclusively as a witness. I was officially informed of that before the interrogation," the ITAR-Tass news agency quoted him as saying. "They made no charges against me."
Lugovoi said the results of his medical tests would be known later this week but said he was "unlikely" to make them public.
German authorities, meanwhile, found traces of polonium-210, the rare radioactive substance that killed Litvinenko, in locations visited by Dmitry Kovtun, another Russian contact, before his Nov. 1 meeting with Litvinenko. The Russian Prosecutor General's office said Kovtun had been diagnosed with radiation poisoning.