The short and vague announcement of the detentions by Federal Security Service director Alexander Bortnikov prompted only skepticism and weak satisfaction from his comrades.

Bortnikov, in comments shown on state television, said the two suspects were from Russia's North Caucasus region, but gave no details other than their names.

He said they were "suspected of carrying out this crime," but it wasn't clear if either of the suspects was believed to have fired the shots that killed Nemtsov as he and a companion walked over a bridge near the Kremlin on Feb. 27. No charges were immediately announced, but the two were expected appear in a Moscow court on Sunday.

Bortnikov didn't say where the detentions took place, how they were conducted or what led agents to the suspects.