The conceptual approaches to the formation and implementation of private criminalistics doctrines (theories) have been considered as scientific constructions that form the basis of the structure of the general theory of criminology and determine the level of development of the theoretical and methodological basis of this science. The author's definition of the notion "private criminalistics doctrine (theory)" has been proposed, and suggestions are made to systematize private criminalistics doctrines and determine their place in the structure of the general theory of criminology. It has been emphasised that the nature of the regularities, explored by each of the particular criminalistics doctrines (theories), determines their order in the structure of the general theory of criminology. At the same time, there are relations of subordination of the whole and the part between the subjects of the general theory of criminology and private criminalistics studies. It is noted that the modern system of private criminalistics doctrines (theories) is dynamic and its improvement is conditioned by the needs of judicial and investigative practice, by the development of related branches of knowledge, the general theory and private criminalistics theories themselves, by changes in connections and dependencies between them. The criteria, that a private criminalistics doctrine (theory) must meet, are determined. The discussion questions in the problem under study are identified, the ways to optimise scientific research in this field of knowledge are outlined

Keywords: criminalistics diagnostics, criminalistics theory, inquiry mechanism, degeneracy mechanism