Russian prosecutors have opened a criminal case in the poisoning death in London of ex-security agent Alexander Litvinenko, as well as the attempted murder of an associate. Bill Gasperini has more for VOA from Moscow.

Alexander Litvinenko

Russian prosecutors say Dimitri Kovtun, a business associate of Alexander Litvinenko, was exposed to the same radioactive substance that killed Litvinenko.

They say the two men met in London on November 1, the day Litvinenko became seriously ill. A third man, who was also part of the London meeting, Andrei Lugovoi, has been undergoing tests for radiation at a Moscow hospital.

Members of the British police are in Moscow carrying out their own investigation of Litvinenko's death, which they are treating as a murder. However, under rules imposed by the Russian prosecutors, the British have not been able to interview any witnesses directly.

A flag over the British Embassy in Moscow

Russian Prosecutor General Yuri Chaika also says the visiting police will not be able to issue arrest warrants, or take any suspects back to Britain with them because Russian law forbids this.

Some analysts have speculated that the Kremlin or others linked with Russia's intelligence agencies may have poisoned Litvinenko, who had long lived in exile in London and was a strong critic of President Vladimir Putin and the Kremlin. In a deathbed letter, Litvinenko accused Mr. Putin of ordering his killing,

Kremlin officials describe the suggestion of official involvement as "nonsense." Many Russians refuse to believe their government is involved in any way, saying the killing may have been committed by people who want to make the Kremlin look bad.

Some British officials say "rogue elements" may have acted independently of the Russian government in a case that has strained relations between Britain and Russia.

Litvinenko died three weeks after he became ill, and traces of radiation have been found in dozens of places where either he or associates went in London.