Tens of thousands of people are gathering in the Russian capital to mourn Boris Nemtsov, the former deputy prime minister turned harsh critic of President Vladimir Putin who was gunned down on a Moscow street last week.
The march, originally scheduled to oppose Russian involvement in Ukraine, was to have been led by Nemtsov himself. Following his murder, however, the gathering has turned into a wake for the fallen opposition leader.
NPR's Corey Flintoff, reporting from the rally in Moscow, says the demonstration is peaceful.
"Mr Nemtsov's allies call it a political killing linked to his opposition to Mr Putin and the Ukraine conflict.
"Opposition supporters are meeting at a point not far from the Kremlin, from where they will march to the spot on Great Moskvoretsky Bridge where Mr Nemtsov was killed."
Russia's Investigative Committee said in a statement on Saturday "that investigators are currently working on two main theories: The murder was either an attempt to destabilize the political situation in Russia or was conducted by Islamic extremists in revenge for Nemtsov's stance over the Charlie Hebdo shooting in Paris," according to The Moscow Times.
However, as The Associated Press notes: "Whoever was responsible for the slaying, the signal it sends to Putin's foes is that if Nemtsov can be killed for his political activism then no one is safe. As a former deputy prime minister and longtime politician, he retained strong ties among Russia's political and business elite."
As we reported on Saturday, Western leaders have called on the Kremlin to allow an independent investigation of the shooting, but Putin has vowed to personally oversee the probe.