Investigators have identified the suspected killer of Chechen human rights activist Natalya Estemirova in July, a law enforcement official told Interfax on Thursday.
But Memorial, the rights group that Estemirova worked for, said it had been unable to confirm the development with investigators.
Estemirova was abducted from outside her home in the Chechen capital, Grozny, on July 15 and was found shot dead hours later on a roadside in neighboring Ingushetia.
The killing drew condemnation from Western governments, and President Dmitry Medvedev has ordered a quick investigation.
"Investigators know the name of the criminal," an unidentified law enforcement official in Chechnya told Interfax on Thursday.
The official said investigators were now looking for the suspected killer, while the identity of the mastermind remains unclear.
Estemirova's colleagues have linked Chechen President Ramzan Kadyrov to her death, saying she had criticized his rule and he had threatened her over her reports on human rights abuses in Chechnya.
Kadyrov has denied involvement in the killing and at the same time said Estemirova lacked "honor, dignity or a conscience." Kadyrov said last month that he believed the murder had been organized by tycoon Boris Berezovsky, who lives in self-imposed exile in Britain.