Russia has detained two suspects for the murder of opposition leader Boris Nemtsov, the head of Russia's federal security Alexander Bortnikov told state television.
Bortnikov said Saturday the two men he identified as Anzor Gubashev and Zaur Dadayev were from the North Caucasus region, but he gave no other details.
It was not clear if either of the two suspects are accused of firing the shots that killed Nemtsov a little more than a week ago. Bortnikov said President Vladimir Putin has been told of the arrests.
At least one gunman shot Nemtsov four times late on Friday, February 27 while he and a female companion crossed a bridge over the Moscow River, just steps from the Kremlin. The woman was not hurt.
Nemtsov was to have led an anti-war and anti-Putin rally in Moscow that weekend. Instead, the rally was transformed into a tribute to Nemtsov whom U.S. President Barack Obama called a "tireless advocate" for the rights of the Russian people.
A few weeks before the shooting, Nemtsov told the Russian news website Sobesednik he thought Mr. Putin wanted him dead, and he did not hold back his contempt for the Russian leader.
"I'm afraid Putin will kill me. I believe that he was the one who unleashed the war in Ukraine. I couldn't dislike him more," Nemtsov said.
Ukrainian President Petro Poroshenko condemned Nemtsov's murder, calling him a "bridge" between Ukraine and Russia.
President Obama called the killing "brutal" murder, and said Russia must carry out a prompt and impartial investigation.
French President Francois Hollande expressed anger at Nemtsov's death. He called the shooting a "hateful murder," and described Nemtsov as a "defender of democracy."
Nemtsov was a deputy prime minister in the 1990s, and many Russian observers predicted he would succeed then-President Boris Yeltsin.
After President Yeltsin chose Vladimir Putin as his successor, and Mr. Putin's subsequent election in 2000, Nemtsov became one of Russia's sharpest and most outspoken Putin critics, especially since last year's uprising in Ukraine.
In September, Nemtsov told VOA that Mr. Putin wants revenge for Ukraine's overthrow of its pro-Russian president.
He said Putin fears that what happened in Ukraine could happen in Russia, and sees a pro-European Ukraine as a threat to his own power.