Two arrested: What do we know now about the murder of Boris Nemtsov?

Two suspects are in custody over last week’s killing of Russian opposition leader Boris Nemtsov – the first sign of progress in the case.

Russian authorities have detained Anzor Gubashev and Zaur Dadayev, two men from the volatile and insurgency-plagued North Caucasus region in southern Russia, according to Alexander Bortnikov, head of the Federal Security Service.

"The individuals detained are, according to our investigation, involved in the organization and execution of the killing of Boris Nemtsov," the committee leading the investigation said in a statement, according to Reuters.

Bortnikov gave no details of how and where the suspects were detained, but he reportedly said Saturday that President Vladimir Putin has been informed of the detainment and that the investigation is ongoing.

The two men in custody are the first signs of any headway in the case since Mr. Nemtsov, a former deputy prime minister and a fierce critic of Mr. Putin, was killed as he walked home on the evening of Feb. 27. Nemtsov was shot four times in the back, within sight of the Kremlin, in the “most high-profile killing of an opposition figure in Putin’s 15-year rule,” according to Reuters.

Some 50,000 people attended a rally to protest the murder Sunday, and thousands more paid their respects when Nemtsov was buried in Moscow Tuesday.

A car and a camera

Neither Mr. Gubashev nor Mr. Dadayev have been formally charged, making it unclear whether either of the men are alleged to have fired the fatal shot. Russia’s Interfax news agency reported that the suspects were identified through phone records along with evidence found in a car they purportedly used, according to the BBC.

Anna Duritskaya, Nemtsov’s Ukrainian girlfriend who was with him the night of his death, has told authorities she saw nothing of the assailants – only a white car, the Financial Times reported.

Security camera footage also provided “sufficiently clear” images of the suspects, Interfax reported, according to the BBC.

Nemtsov’s political ally Ilya Yashin expressed skepticism that this investigation would distinguish itself from previous cases of political assassination in post-Soviet Russia – none of which have ever been solved. 

"Often in such high-profile cases it comes down only to detain the perpetrators, thus enabling the authorities to get a nice picture on TV," Mr. Yashin wrote on his Facebook page. "But if [authorities] will be able to avoid responsibility, the practice of political assassinations, will no doubt continue."

Few facts, many theories

Little else is known of the who and the why behind Nemtsov's murder, at this point. But theories have flourished.

The day after the fatal shooting, Russia’s Investigative Committee released a statement outlining several possible motives. These included everything from Islamic extremists offended by Nemtsov’s position on the Charlie Hebdo killings in Paris to someone angered by his affair with the much younger Ms. Duritskaya.

Another theory – one that echoed remarks by Putin’s spokesman and other Russian politicians – was that Nemtsov was a “sacrificial victim,” and that his murder was an attack on Russia’s political stability.

“The term ‘sacrificial victim’ was also the same one Putin used three years ago when he warned that his political opponents were planning to kill one of their own and then blame it on his government,” according to the Associated Press.

Others have noted that the Kremlin skirted one other possibility: That Nemtsov was killed for his vocal criticism of Putin’s regime.

“Think about this for a moment. If you are someone who opposes Putin right now and you see a high-profile leader shot in the street, you are going to be afraid,” Amy Knight, a Russian political expert who knew Nemtsov professionally, told The Christian Science Monitor. “I believe that’s a far more credible motive than to say it was his own party or a foreign faction, etc.”

At the time of his death, Nemtsov was looking into what he said was “dissembling and misdeeds in the Kremlin,” The New York Times reported. He reportedly told Yevgenia Albats, editor of the Russian magazine New Times, that he planned to publish a pamphlet, to be called “Putin and the War,” that would reveal the Russian government’s involvement in the 11-month-old Ukrainian conflict.

“He was afraid of being killed,” Ms. Albats, who met Nemtsov to discuss his plans about two weeks before his murder, told The New York Times.

“And he was trying to convince himself, and me, they wouldn’t touch him because he was a member of the Russian government, a vice premier, and they wouldn’t want to create a precedent,” she added. “Because as he said, one time the power will change hands in Russia again, and those who served Putin wouldn’t want to create this precedent.”