MOSCOW, August 6 (RAPSI) - Four witnesses in the Anna Politkovskaya murder case will be questioned behind closed doors, RAPSI reported from the courtroom on Tuesday.

Prosecutor Maria Semyonenko said that testimonies of these witnesses are marked as top secret, that's why they should be questioned behind closed doors, without journalists and audience.

Novaya Gazeta newspaper journalist Politkovskaya was shot and killed in her apartment building on October 7, 2006. Her murder has been linked by some experts to her coverage of human rights abuses in Chechnya.

The five suspects include former police officer Sergei Khadzhikurbanov, Rustam, Ibragim, and Dzhabrail Makhmudov, and their uncle Lom-Ali Gaitukayev.

A sixth suspect, former police officer Dmitry Pavlyuchenkov, who earlier signed a plea bargain, gave evidence against his accomplices and was sentenced to 11 years in prison in December 2012.

The investigators believe that Rustam Makhmudov committed the murder with the help of his brothers Ibragim and Dzhabrail, their uncle and Khadzhikurbanov.