Relatives and allies of an opposition politician imprisoned in Russia say they haven't heard from him in a month and are worried about his well-being.
Andrei Pivovarov, who was sentenced to four years in prison last year, was transferred from a detention center in southern Russia in December. In the following weeks, he occasionally wrote letters to his loved ones from detention centers in other Russian cities, stopovers on the way to his undisclosed final destination.
