The killing of a key opposition figure is a "disgrace" to Russia, President Vladimir Putin said on Wednesday.
In televised remarks to interior ministry employees, Putin condemned the slaying of Boris Nemtsov, who was gunned down while walking near the Kremlin late on Friday.
While the Kremlin said on Saturday that Putin had sent his condolences to Nemtsov's mother, his comments Wednesday were Putin's first public remarks on the subject.
"The most serious attention must be paid to high-profile crimes, including those with a political motive," Putin said. "We must finally rid Russia of the disgrace and tragedy of the kinds of things we recently saw and experienced: I mean the audacious murder of Boris Nemtsov in the very center of the capital."
Nemtsov, one of Putin's most vehement critics, was killed just hours after a radio interview in which he denounced the President for his "mad, aggressive" policies in Ukraine. He was also working on a report about Russian involvement in the war in eastern Ukraine.
No suspects have been detained yet in the 55-year-old's killing, despite an offer of 3 million rubles (nearly $50,000) for information related to the case.
On Wednesday, in response to questions about any possible suspects in Nemtsov's killing, Federal Security Service chief Alexander Bortnikov told Russian news agencies that "there are always suspects." He did not elaborate.
The one witness is 23-year-old Anna Duritskaya, a Ukrainian citizen who was walking with Nemtsov when the shooting occurred.
Duritskaya told news outlets Monday that the lone attacker approached the couple from behind. Russian authorities said Nemtsov was hit by four shots. Duritskaya said she hadn't seen the person, nor could she identify the license plate or make of the getaway car the attacker then sped away in. She was detained by Russian police for several days of questioning then returned on Tuesday to her hometown of Kiev.