The court on July 27 said Russian authorities had failed to carry out an effective criminal investigation into the disappearance and presumed death of Khadzhi-Murat Yandiyev.
It also ordered Russia to pay his mother 35,000 euros ($45,000) in damages.
Television news in 2000 showed Yandiyev being interrogated by a Russian officer, who then ordered him shot.
The Chechnya Conflict
The aftermath of a December 2002 Chechen resistance attack on the main government building in Grozny (epa)