LONDON (AP) -- The British coroner examining the poisoning death of an ex-KGB officer ruled Thursday the question of whether Russia was responsible will be withdrawn from the scope of the inquiry.
Robert Owen also said he won't examine whether Britain was aware of any risks to Alexander Litvinenko's life, and failed to take reasonable steps to protect him before he died after drinking tea laced with the radioactive isotope polonium-210.
Owen made the announcement following a successful legal bid by the U.K. government to keep documents under wraps that might be relevant to explaining what happened to the officer-turned-dissident who was a critic of Russian leader Vladimir Putin. Owen said that because all the evidence available can't be considered, any conclusion would be incomplete.
The coroner was particularly pointed on the question of whether Britain might have prevented the murder.
"This is an issue of the highest importance, involving as it does the possible culpability of the British state for the death of Alexander Litvinenko," he wrote. "If any investigation of this issue is to be embarked upon, it must be an investigation which can properly and thoroughly examine the issue, so that a conclusion soundly based on reliable factual evidence can be arrived at."
Britain has accused two Russians of the 2006 killing, but Moscow has refused to extradite them.
The government has ruled out a public inquiry into the ex-officer's death. Home Secretary Theresa May cited financial cost among the reasons, but also said that it was "true that international relations have been a factor in the government's decision-making."
Litvinenko's widow, Marina, has accused Britain of putting relations with Russia ahead of uncovering the truth.