LONDON - A former KGB agent turned Kremlin critic who was poisoned three weeks ago was moved into intensive care Monday after his condition deteriorated, and his doctor said the toxin has attacked his bone marrow. Prominent Russian exiles claimed Litvinenko was poisoned at the behest of the Kremlin... Thallium causes hair loss and interferes with the cardiovascular and nervous systems, attacking the vital organs. Litvinenko's white cell count is down to nearly zero, said Dr. John Henry, a clinical toxicologist treating him. "It shows his bone marrow has been attacked and that he is susceptible to infection," Litvinenko, who...