Former policeman Dmitry Pavlyuchenkov was tried and found guilty of arranging the murder of Russian journalist Anna Politkovskaya, who was found shot dead in a lift at her block of flats in Moscow in 2006.
Pavlyuchenkov struck a plea bargain in court admitting his guilt, but without having to testify.
The other defendants include the alleged killer and getaway drivers, who all belong to the same Chechen family.
At the time of her murder, Politkovskaya was working for Novaya Gazeta, a small newspaper known for its reports, which strongly criticised the Russian authorities.
The paper’s editor-in-chief stated that there was a “political taboo” on identifying exactly who ordered the assassination.
But the family of Politkovskaya has argued that without Pavlyuchenkov’s testimony, they will never fully get to the bottom of her death.