The assassination of Boris Nemtsov, a former Russian bureaucrat and frequent critic of President Vladimir Putin, could trigger more instability and fear across the country as several theories about who committed the brazen act and why remains unsolved, political experts warn.
Putin vowed Saturday, hours after 55-year-old Nemtsov was gunned down on a street just steps from the Kremlin in Moscow, to find whoever orchestrated the "vile and cynical murder." Nemtsov was supposed to appear at a Sunday rally protesting Russia's role in the fighting in Ukraine — now that march will be a memorial. Some inside Russia believe the president and his powerful inner circle will have to answer for Nemtsov's death because he was such a staunch critic of Putin's policies.
"Whether it was ordered by the Kremlin, or against the Kremlin, or regardless of the Kremlin, it is Putin and it is the presidential administration that has created the situation of civil war within Russia, of a war with a neighboring nation (Ukraine)," said Sergei Medvedev, a professor at the Higher School of Economics in Moscow.
"It has created a situation of inherent instability and hatred, and this hatred has just materialized yesterday — and there’ll be more to come," Medvedev told NBC News.
Nemtsov, a former deputy prime minister in the 1990s, was shot four times in the back by killers in a white car late on Friday as he walked across the bridge over the Moskva River in Moscow with a Ukrainian woman, police said. She was not harmed.
Police sealed off the blood-stained bridge close to the red walls of the Kremlin and Red Square for two hours overnight, then hosed it down as people came to pay tribute to one of Putin's biggest opponents.
Russia's Investigative Committee, which answers to Putin, said it was following several lines of inquiry, including that the opposition may have committed the crime to rally support for a march against Kremlin policies on the economy and Ukraine.
Flowers were piled at a memorial site and a piece of white paper saying, "We are all Nemtsov," stood among the tokens. "People are afraid to support our movement. Opposition activists receive threats every day and Boris was no exception. But they won't stop us," said opposition activist Mark Galperin.
Medvedev said it is Putin who has been "destabilizing" the situation in Russia by meddling in eastern Ukraine, where pro-Russian separatists have been battling with Ukrainian troops over the past year. A new cease-fire agreement for the area has been shaky at best.
Medvedev added that Nemtsov paid the price for being so outspoken. "He was very open, frank, sincere ... and very courageous," Medvedev said, adding, "He set a standard of fearlessness."
— Alexey Eremenko and Erik Ortiz
Reuters contributed to this report.