Moscow: Russian President Vladimir Putin Saturday pledged to do everything to bring the killers of opposition leader Boris Nemtsov to justice.
"We will do everything to ensure that the perpetrators of this foul and cynical crime and those who stand behind them are properly punished," Putin said in a condolence message to Nemtsov`s mother, according to a Xinhua report.
Nemtsov was shot dead in downtown Moscow in the intervening night of Friday-Saturday. He was the former deputy prime minister of Russia and the co-chair of the RPR-Parnas party. He had held a number of government positions in the 1990s.
"Boris Nemtsov has left his mark in the history of Russia (and) in its political and public life. He occupied significant posts in a difficult time of transition in this country. He always openly and honestly voiced and upheld his views," the president added.
The Russian Investigative Committee launched a comprehensive investigation into the incident, and is probing several possible causes behind the assassination, including an attempt to destabilise the political situation in Russia, the conflict in Ukraine and personal animosity.
Earlier in the day, Russian Prime Minister Dmitry Medvedev said he was shocked by Nemtsov`s killing, adding that "this is a personal tragedy for his relatives and friends and a great loss for our society".
On Saturday afternoon, crowds of people, some with flowers in their hands, flocked at the site of the attack to mourn the death of the noted leader.