Moscow ? A key witness in the poisoning death of former Russian security service defector Alexander Litvinenko said Monday that he had been questioned again by investigators probing the case.

“Today I met with representatives of the (Russian) Prosecutor General’s Office and the British police, and gave comprehensive answers to all their questions,” Dmitry Kovtun, also a former security service agent, told RIA Novosti. He stopped short of revealing any details.

Kovtun, who had his first interview with Russian prosecutors and detectives from Scotland Yard on Dec. 6, met with Litvinenko in a London hotel Nov. 1, just before the defector complained of feeling ill and was hospitalized with symptoms of poisoning.

Litvinenko died three weeks later.