Four men suspected of being behind a deadly bomb attack last year at a Moscow airport are due to appear in court on Monday.
The preliminary hearing will be held behind closed doors, a spokesman for the Moscow Region court told journalists.
The suicide attack on the arrivals area of Domodedovo international airport in January 2011 left 37 people dead and 173 injured.
Akhmed Yevloyev, Bashir Khamkhoyev and brothers Islam and Ilez Yandiev helped set up the attack by providing accommodations for the bomber, supplying the explosives and choosing the busy airport location he struck, investigators say.
Chechen warlord Doku Umarov has said he ordered the bombing.