Vladimir Markin, an investigation committee spokesman, said that the suspect, Shamil Buraev, was released pending trial. He was released on the grounds that he had no previous convictions, had not attempted to evade the authorities, and that he had four children and a father over 100 years old.
Four of the nine suspects had earlier been released from custody, also pending trial.
Another suspect, Kyrgyz national Rustam Makhmudov, has become the subject of an international manhunt, a spokesman for the investigation committee at the Russian Prosecutor General's Office announced earlier.
Markin also said that the preliminary investigation would be completed by June 20, and that the case materials would be made available to Politkovskaya's son, and then to the defendants.
Politkovskaya, who gained international recognition for her criticism of the Kremlin and reports of military atrocities against civilians in the troubled Caucasus republic of Chechnya, was gunned down in the entranceway of her Moscow apartment building in October 2006.
Russia remains one of the world's most dangerous countries for reporters. According to data from the international organization Reporters Without Borders, 21 journalists were murdered in Russia between 2000 and 2007.
