This is the first edition of previously unknown documents on the participation of the Left Social Revolutionaries in the creation and activities of the Cheka. For the most part, these documents are still stored in the Lubyanka, in the archive of the former KGB. In the years 1917-1918. the Left Socialist Revolutionaries were the second, after the Bolsheviks, the ruling party and with them built a totalitarian state and its punitive institutions.