MOSCOW — Russian investigators have charged a retired police officer with helping organize the 2006 killing of an investigative reporter who was gunned down in the elevator of her Moscow apartment building.

The killing of Anna Politkovskaya, a sharp critic of Kremlin policies in Chechnya, caused widespread suspicions of government involvement. Six men have been charged with the killing, but investigators still have not named the person who ordered the assassination.

Investigative Committee spokesman Vladimir Markin said Monday that Dmitry Pavlyuchenkov, who was a lieutenant colonel at the time of the killing, has been formally charged 11 months after his arrest. Investigators said earlier that Pavlyuchenkov tracked down Politkovskaya's movements to help the suspected triggermen.

Pavlyuchenkov served as a witness during the 2009 aborted trial of two Chechen brothers and another ex-police officer.