This collection was prepared on the materials of commissions created in different years (1956, 1961, 1967 and 1989) by decisions of the Politburo (Presidium) of the CPSU Central Committee to investigate the circumstances of the murder of S. M. Kirov. This huge array of documents was deposited in the Russian State Archive of Contemporary History (RGANI) and was mainly declassified already in the post-Soviet period. The published set of archival materials is designed to acquaint readers with the most significant documents that comprehensively reflect the actual side of the events and the main directions of investigations.