We'll begin this blog with a few of the stories that we've produced in the hours since Russian media made the shocking announcement that 55-year-old opposition politician and former Deputy Prime Minister Boris Nemtsov had been killed, apparently shot four times from a car as he walked across a bridge with a companion in the heart of Moscow.
And this excellent obituary from Washington correspondent Carl Schreck, who spent many years as a journalist in Russia.
Boris Nemtsov, A Russian Political 'Golden Boy' Who Battled Putin, Dead At 55
Looking ahead to a planned March 1 opposition rally, in an interview with RFE/RL’s Russian Service earlier this month, Nemtsov portrayed the demonstration as just a first step in a long struggle.
Boris Nemtsov: 'We Must Free Russia From Putin'
Russian Opposition Cancels Sunday's Rally In Marino District
Leonid Volkov, an opposition activist and close ally of Aleksei Navalny, wrote on Twitter that the opposition rally due on Sunday has been canceled despite weeks of intense preparations because of the "force majeur" of Nemtsov's death. He said the city authorities had approved a march of mourning in central Moscow to the spot where Nemtsov was gunned down.
"3. The march will happen tomorrow at 15:00 from Kitai-Gorod to the bridge to the place of the death, the march has been agreed with City Hall, we can and must call everyone there"
In a move that some are interpreting as a sign that any investigation might be seriously compromised, authorities appear to have washed away potential clues within hours of the killing. In this shocking video from our Russian Service, firemen use hoses to clean the crime scene as a crowd gathers.
Our Russian Service is live-streaming clips (in Russian) of Nemtsov's colorful career, discussion of his legacy, and analysis of what his death means.
Gleb Pavlovsky, a former Kremlin spin doctor, wrote on Facebook:
"A person who drives -- not just anywhere, but on Red Square to kill a former member of government, an opposition figure under the lights and video cameras of the Kremlin walls where hundreds are positioned -- is making a political demonstration. It is an address to the country and to the authorities that is no less powerful than an address from the president. Not to heed it and react to it will cost dear."
LATEST: U.S. Ambassador to Russia John Tefft has laid flowers today at the scene of the Nemtsov killing, Russian and other media report.