Russian security services have blamed two members of a fascist gang for the murders of human rights lawyer Stanislav Markelov and journalist Anastasia Baburova.
The arrest of Nikita Tikhonov, 29, and Yevgenia Khasis, 24, was confirmed on Thursday when the two suspects appeared in court wearing black stockings over their faces - echoing the disguises worn by the killers in the January shooting in central Moscow.
Federal Security Services chief Alexander Bortnikov told President Dmitry Medvedev that the killer had confessed to the crime, one of a string of contract-style killings against journalists and human rights campaigners. Tikhonov's lawyer said on Friday that his client had confessed to the killing, but insisted he was acting alone.
Tikhonov was a suspect in the 2006 murder in Moscow of anti-fascist activist Alexander Ryukhin. Several members of a fascist gang were found guilty of Ryukhin's murder in 2007, but Tikhonov evaded arrest.
Markelov, who represented Ryukhin's family in the case, had identified Tikhonov as a member of the fascist group United Brigade-88, named after the initials in the Nazi salute "Heil Hitler", according to the Sova human rights group.