Russian investigators have finished a probe into four men suspected of being accomplices to the deadly bombing of Moscow's Domodedovo Airport in January 2011, a spokesman for the Russian Investigative Committee, Vladimir Markin said.

The blast, which killed 37 people and left 173 injured, was organized by Chechen terrorist, Doku Umarov, whose gang included about 35 people, the Russian investigator have concluded, as cited by RIA Novosti.

Among the main suspects were suicide bomber Magomed Yevloyev, 20, who blew himself up in the arrival hall of Domodedovo airport on January 24, 2011, as well brothers Islam and Ilez Yandiyev, who were detained in March 2011 in the North Caucasus republic of Ingushetia, and Bashir Khamkhoyev, 19, who had also been arrested, Markin said.

The investigators carried out 600 examinations, including linguistic, psychological, photographic, explosive and biological checks and almost 400 forensic checks.

The investigation into the organizers of the terrorist attack is underway, the Investigative Committee's spokesman said.