An alleged former member of the separatist insurgency in Chechnya has been detained in Russia's southern Stavropol Krai region.
The Investigative Committee in a December 12 statement identified the suspect as Shamil Kazbulatov, born in 1972.
Kazbulatov is suspected of taking part in a February 2000 attack in Chechnya's Shatoi district in which 84 Russian soldiers were killed.
In November, the Investigative Committee said two other men, Nazhmudin Dudiyev and Ibragim Donashev, had been arrested on suspicion of taking part in the assault by an armed separatist group led by Shamil Basayev.
The attack has been officially seen in Russia as an example of bravery and sacrifice by Russian soldiers, although some military experts in the country consider it as a defeat that could have been avoided.
Basayev has led several major attacks by Chechen insurgents against federal troops and terrorist acts in the North Caucasus between 1994 and 2006.
Once the most wanted man in Russia, he was killed in an explosion in 2006 in Ingushetia, a North Caucasus region neighboring Chechnya.