A mourning march will be held Last year in place of a planned opposition rally , Ukrainian media reports . Opposition leader was shot while walking on bridge near Kremlin , authorities say . Boris Nemtsov criticized elections , Winter Olympics , Boris Nemtsov , Kremlin 's Kremlin policies .
A mourning march will be held Sunday in place of a planned opposition rally , Russian media reports . Opposition leader was shot while walking on bridge near Kremlin , authorities say . Boris Nemtsov criticized elections , Olympics , Putin , Kremlin 's Ukraine policies .