Moscow authorities have charged two men with involvement in the murder of Kremlin critic Boris Nemtsov, and one of the suspects had served in a police unit in the Russian region of Chechnya, according to a law enforcement official.
A total of five men were frog-marched into a Moscow courtroom on Sunday, forced by masked security officers gripping their bound arms to walk doubled over. Three of them have not yet been charged and are being treated as suspects, said court spokeswoman Anna Fadeyeva.
Court officials named Anzor Gubashev and Zaur Dadayev as the two charged, and said Gubashev's brother Shagid was one of the three suspects. Russian media reports said they originated from Chechnya, the mainly Muslim republic in Russia's southwest that has hosted a low-burning separatist insurgency over the past two decades.
The judge at Dadayev's hearing, Natalia Mushnikova, said Dadayev had admitted involvement in the killing and ordered him to be held in custody until April 28.
"Dadayev's involvement in committing this crime is confirmed by, apart from his own confession, the totality of evidence gathered as part of this criminal case," she told the court.
Nemtsov was shot dead just before midnight on Feb. 27 within sight of the Kremlin walls, in the highest-profile killing of an opposition figure in the 15 years that President Vladimir Putin has been in office.
Some associates of Nemtsov, a 55-year-old former deputy prime minister who became a Putin critic, say the Kremlin stands to gain from his death. They insist they will only be satisfied if prosecutors track down whoever orchestrated the killing, rather than just those who pulled the trigger.
Several other high-profile killings in Russia — including the 2006 shooting of journalist Anna Politkovskaya — have been attributed to gunmen from Chechnya and neighboring regions, and those who ordered the crimes were never firmly identified.
Russian officials have denied involvement in Nemtsov's death. Putin has decried the incident as a "provocation," suggesting Nemtsov was killed by one of Putin's enemies to stoke discontent in Russia.
Another theory presented by Russian police is that Nemtsov may have been targeted for his reported support of French satirical magazine Charlie Hebdo, which was attacked in January for its controversial depictions of the Prophet Muhammad.
No motives were identified by the Russian government on Sunday. A security official in the southern Russian region of Ingushetia where some of the suspects were detained, Albert Barakhayev, told Russian news agencies that Dadayev had served for about 10 years in the "Sever" police battalion, part of the interior ministry of the neighboring region of Chechnya.
There was no immediate confirmation of that from the Chechen authorities, and it was not clear if Dadayev was still a serving member of the battalion.
Court officials named the other two suspects as Ramzan Bakhayev and Tamerlan Eskerkhanov.
Chechnya is now firmly under the control of its leader, Ramzan Kadyrov, a former rebel who now pledges loyalty to Moscow and has considerable autonomy over the running of the region, including its security services.
There have been cases in the past where employees of Russian law enforcement agencies have been prosecuted after moonlighting for organized crime groups.
Russia's Interfax news agency, quoting a Chechen law enforcement source, said a man killed in a standoff with police in the Chechen capital late Saturday was wanted by police in connection with Nemtsov's killing.
The agency said when police arrived at an apartment block, the man threw one grenade at officers and then blew himself up with a second.
Nemtsov's closest aide told Reuters that the day before his death he had clandestinely scribbled a note to her about how he was investigating the involvement of Russia's military in fighting in east Ukraine.
Some of Nemtsov's friends have asked why the police took so long to arrive at the scene of the crime, and how someone could fire six shots at him and get away in an area monitored by closed-circuit television footage.
Al Jazeera and The Associated Press