Two suicide bombings struck in Volgograd Dec 29 and Dec 30 separately, leaving at least 34 people dead and scores of others wounded.
According to media reports Monday, Sochi police were searching for a suspected member of the "Black Widow", a militant group, who planned to launch a terror attack during the games.
A video was posted online Sunday, in which two suicide bombers believed to have launched the Volgograd attacks warned they had "prepared a present" for tourists who will attend the Winter Olympics.