The published work is one of the first studies in the open scientific literature of the issues of legal regulation of citizens' assistance to bodies - subjects of operational investigative activities. The monograph is based on the available literature, extensive regulatory and legal material and documentary sources previously not available to a wide range of readers. The appendices contain the texts of rare documents from the history of operational investigative activities and investigation, as well as the text of the current Federal Law “On Operational Investigative Activities” dated August 12, 1995. For all those interested in the issues of legal regulation of operational investigative activities and the history of its development.