A Russian court Sunday charged two men with the murder of opposition activist Boris Nemtsov, including an ex-police officer from Chechnya who confessed to his involvement in the brazen assassination.

Five suspects appeared in a court in central Moscow a little over a week after Nemtsov, a longtime critic of President Vladimir Putin, was shot four times in the back as he strolled with his girlfriend along a bridge in full view of the Kremlin.

Court spokeswoman Anna Fadeyeva told the RIA Novosti news agency that three of the men who were not charged were only considered suspects at this stage. All five were remanded in custody.

Zaur Dadayev, a former deputy commander for the Chechen police, and Anzor Gubashev, who worked for a private security company in Moscow, were arrested Saturday in the republic of Ingushetia, which neighbours Chechnya.

They were both charged with murder but Gubashev denied involvement. “The participation of Dadayev is confirmed by his confession,” said presiding judge Nataliya Mushnikova.

However no information has emerged as to the possible motive the men could have had in killing the charismatic opposition leader.

His allies believe his assassination was a hit ordered by the top levels of government determined to silence dissenters. The allegation has been strenuously denied.

On Sunday the Investigative Committee announced three further arrests in the case: Gubashev’s younger brother Shagid, Ramsat Bakhayev and Tamerlan Eskerkhanov, who news agencies reported had also been arrested in Ingushetia.

The men are all from the volatile northern Caucasus region where Russia has fought two devastating wars against Chechen rebels and where security forces continue to clash with Islamist insurgents.

“The suspects denied their involvement in this crime but investigators have proof of their involvement,” a representative for the probe told the court of the three.

The Interfax news agency meanwhile cited a source in law enforcement as saying that another suspect sought by police over the murder had holed himself up in the Chechen capital Grozny Saturday and blown himself up with a grenade after throwing another at police surrounding the building.