In the article on the basis of the generalization of expert practice in forensic lever locks research, on the example of research of lever locks, the signs are shown, which are reflected in the tracks on the details of the locks when opened by their native and selected keys. On the examples of several expert researches on practice, the stage of comparative research is described when comparing conformal traces to component parts of locks (lever tumblers) with working surfaces of the key beards. As examples, a list of signs and traces that are formed on the surfaces of the details of locks, in the process of opening them and native and selected keys. It is indicated the significance of this stage of study of lever locks for the purpose of their disclosure. The descriptions and illustrations of comparison of the detected traces with native and selected keys, which were used to open the locks investigated are given. Similarly, the article describes the algorithm of conducting similar studies and the approach to integrated assessment, as the traces themselves on the details of the lock mechanism, and the native keys, which created the operational traces on the details of the locks. The necessity of carrying out the stage of comparative research, determination of the mechanism of formation of traces and the necessary and sufficient complexes of signs of disclosing a lever lock with a selection key are determined. It is indicated the possibility of establishing a specific non-native key, which opened the investigated lock.
According to the results of the analysis, the recommendations for a comprehensive expert approach to the assessment of the characteristics that are reflected in the traces revealed in the research objects.