TY JOUR TI Study of the legal category "official" as a factor in improving the quality of law in the field of operational investigation. KW research of legal category KW official KW functions KW powers KW legal responsibility JO Vestnik of the St. Petersburg University of the Ministry of Internal Affairs of Russia AU Kurtyak, A.I. PY 2019 IS 2019 PB SAINT-PETERSBURG UNIVERSITY OF THE MINISTRY OF INTERNAL AFFAIRS OF THE RUSSIAN FEDERATION