The widow of Russian spy Alexander Litvinenko has told ITV News she is "not fighting with Russia" in her battle to discover the circumstances surrounding his death.
Mr Litvinenko's family believes he was working for MI6 at the time of his death from radioactive poisoning and claim was killed on the orders of the Kremlin.
Speaking as a public inquiry into his death got underway, Marina Litvinenko said she "can't be calm until we realise who commited this crime".
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The singer, 31, said on Twitter that she and her partner Jonathan Powell were grieving their loss.