The Russian president's Kazakhstan visit has been delayed indefinitely but the Kremlin dismisses health rumors.
Critics of Vladimir Putin say his government has encouraged a hostile political environment that leads supporters to act out violently.
A member of the Kremlin’s rights council said that Zaur Dadaev confessed to killing Boris Nemtsov under duress.
A local newspaper posted the photo of Nemtsov's killers in what's said to be a getaway car, but it was unclear when the picture was taken.
British Foreign Secretary Philip Hammond accused Russian President Vladimir Putin of "subverting" the peace between nations.
The man some call a warlord has praised one of Nemtsov's alleged assassins as a "true Russian patriot."
A trailer of a new documentary shows Putin speaking about an all-night meeting that discussed annexing Crimea.
The Royal United Services Institute said the army could face massive spending cuts, after the general elections in May.
Nemtsov's associates believe that the Kremlin stood to gain from the killing because he was determined to expose official corruption.
One of two men charged in the killing of Boris Nemtsov has admitted guilt. But it is unclear which crime he has confessed committing.
Russian news agencies reported that the suspect served in a police unit in the strife-torn region of Chechnya.
Two men have been detained over the Russian opposition figure's slaying, according to the head of the country's Federal Security Service.
Alexei Navalny's imprisonment coincided with the murder of fellow Putin critic Boris Nemtsov.
Boris Nemtsov had criticized Putin in a radio interview hours before he was murdered in Moscow last Friday.
The head of Russia’s Security Council accused the U.S. of funding Russian opposition groups.
Boris Nemtsov's allies have pledged to publish a report he was working on at the time of his death.
At least 17 deaths at a Ukraine coal mine Wednesday bring the 15-year death toll there to more than 300.
Before his death, Boris Nemtsov, a vocal critic of Putin, had been organizing an upcoming rally in protest of the conflict in eastern Ukraine.
Nemstov was respected in Russian politics, despite his views. Few other opposition leaders had the support he did.
Cameras were either turned off or failed to capture relevant footage when Russian opposition leader Boris Nemtsov was killed, reports say.
Anna Duritskaya, 23, is purported to be the lone witness to the Russian opposition leader's killing.
Inna Duritskaya also claimed that Russian President Vladimir Putin is trying to link the murder to the conflict in eastern Ukraine.