The arrest of Dmitry Pavlyuchenkov was the latest twist in the long-running legal saga to find the killers of the anti-Kremlin journalist which has raised numerous concerns about the rule of law in Russia.

The mastermind of the killing has still not been identified.

Herewith follows a chronology of key dates in the process to bring her killers to justice:

— October 7, 2006: Anna Politkovskaya is shot dead in the stairwell of her apartment in Moscow in an apparent contract killing after returning from a shopping trip.

— October 10, 2006: Russia’s then president Vladimir Putin says the killing was “an unacceptable crime that cannot go unpunished” but also describes her ability to influence political life in Russia as “insignificant”.

— August 27, 2007: Russian prosecutors announce the arrest of 10 people in connection with the murder in what they describe as a major breakthrough in the case.

— October 8, 2007: Investigators say they have identified the killer who they later say is in hiding in western Siberia.

— June 18, 2008: Russian prosecutors charge three men over the killing but admit that the assassin remains at large. Of the suspects, Dzhabrail and Ibragim Makhmudov are Chechen brothers while Sergei Khadzhikurbanov is an ex-police investigator.

The suspected gunman, Rustam Makhmudov, who is the brother of Dzhabrail and Ibragim Makhmudov, remains at large.

— November 17, 2008: The trial into the murder opens at a Moscow court with all the suspects present. The defendants plead not guilty.

— January 19, 2009: Anastasia Baburova, a young journalist working on Politkovskaya’s Novaya Gazeta newspaper and rights lawyer Stanislav Markelov are gunned down in central Moscow as they emerge from a news conference.

— February 19, 2009: A jury in the trial acquits all the accused after three months of hearings that observers lament failed to shed any significant light on the case. The three suspects walk free.

— June 25, 2009: The Russian supreme court quashes the acquittal verdicts and orders a new trial of the three suspects.

— July 15, 2009: Poltikovskaya’s friend and fellow campaigner against abuses in the Caucasus, Natalya Estemirova, is found shot dead after being abducted in Chechnya.

— August 4, 2009: The new trial opens with the same suspects accused. The suspected killer remains at large and the mastermind has still not been identified.

— September 3, 2009: The Russian supreme court halts the new trial and orders the case be brought back to prosecutors to search for the assassin.

— October 6, 2010: Russian investigators ask for more time to investigate the murder, amid few signs of tangible progress in the probe four years after her death.

— May 31, 2011: Russia announces the arrest of suspected gunman Rustam Makhmudov accused in the investigation of firing a series of bullets into Politkovskaya’s body. He is then charged with murder.

— August 24, 2011: Russia announces the arrest of retired police lieutenant colonel Dmitry Pavlyuchenkov on suspicion of organising the criminal group that carried out the murder as well as obtaining the murder weapon.