Opposition leader Boris Nemtsov was shot dead while walking near Kremlin with girlfriend . The gunman has been identified as Alexander Zaldostanov, a former member of the Russian military intelligence service who had served in Chechnya and Afghanistan. Russian President criticizes `` extremists '' for use of `` illegal street protests '' and social media .
Opposition leader Boris Nemtsov was shot dead while walking near Kremlin with girlfriend . Vladimir Putin : Russia should be safe from `` disgrace and tragedies '' like Nemtsov 's killing . Russian President criticizes `` extremists '' for use of `` illegal street protests '' and social media .