Russian state role seen in death of poisoned spy

LONDON — New testimony that emerged Thursday deepened the intrigue surrounding the death of the former K.G.B. officer Alexander V. Litvinenko, offering “prima facie” evidence of Russian state involvement and indicating that he had been a paid agent of the British Secret Intelligence Service, MI6, lawyers at a preliminary inquest hearing said.

The accusations evoked the murky world of rumor, claim and counterclaim in which Mr. Litvinenko appeared to operate before his death in November 2006 and raised questions about his role in the twilight arena of competing intelligence services.

Mr. Litvinenko died after ingesting a rare and highly toxic radioactive isotope, polonium 210, which British investigators later traced to a pot of tea served to him at an upscale hotel in Grosvenor Square, opposite the American Embassy in central London. British prosecutors have charged another former K.G.B. operative, Andrei K. Lugovoi, with the killing. Mr. Lugovoi has denied the charge....