A lawyer for Paul Whelan, a former U.S. marine jailed in Russia on espionage charges he denies, told Reuters on Wednesday she was unable to confirm his whereabouts. Olga Karlova, the lawyer, said she had sent a request to the prison colony where he is serving out his term in order to find out where he is. A number of Russian dissidents and people convicted for their opposition to Moscow's war in Ukraine have disappeared from Russian prisons in recent days, in what rights activists say is a possible sign that a prisoner swap with the West involving people like Whelan may be close.