LONDON (Reuters) -Russia said on Thursday it had opened a criminal investigation into allegations by a Russian soldier that he was beaten and received death threats while being held as a prisoner of war in Ukraine. Russia’s Investigative Committee said the man, identified only by the initial E, was captured after a battle on March 2 in which he was seriously wounded. The soldier, a private, was returned to Russia after a prisoner swap on April 1, it said. During that time, the Committee said he was repeatedly interrogated by both military personnel and people in civilian clothes with masks on …