forensic ballistics

A Probabilistic Assessment of the Complexes of Combined Traces in Secondary Tracks on Fired Bullets

Introduction. The paper analyzes the effectiveness of the application of the method of successively matching traces (CMS method) and the probabilistic method for substantiating the forensic identity of the overlapping secondary traces on fired bullets. Theoretical analysis. The theoretical foundations of the CMS method and the probabilistic method are considered. It is shown that the second method is formed on the basis of two mutually complementary probabilistic models. Experimental studies of the effectiveness of assessing the uniqueness of the complexes of combined tracks. The studies were conducted for secondary traces with high and low track density (for tracks on bullets fired from PM and AK-74, respectively). Potential trace identity criteria were defined for traces with low track density according to the CMS method. The authors determined the probabilistic criteria for the identity of the compared traces with high and low track density. It is shown that for traces with a low track density, the criterion of potential identity is the probability of random alignment of tracks no more than 5*10-3, and for traces with a high density of tracks the probability is no more than 10-6. Results. The probabilistic method allows you to obtain a quantitative assessment of the uniqueness of coincident features and correctly substantiate a categorical positive conclusion when identifying firearms by traces on fired bullets.

 Izv. Saratov Univ. (N. S.), Ser. Economics. Management. Law, 2020, vol. 20, iss. 2
Current Issues of the Criminalistic Classification of the Self-made Firearms

Introduction. The development of small weapon and structurally similar products, their use for criminal purposes force forensic science and practice to make adjustments to the forensic classification system of firearms over and over again. Theoretical analysis. In forensic ballistics, firearms are classified according to their purpose, type, method of production, barrel length, barrel channel device, number of barrels, etc. By the method of manufacture, groups of factory, artisanal and improvised firearms are distinguished. At the same time, the system of signs developed by science for the self-made manufacturing method is not effective for all cases of expert research. It is the expert practice that gives the reasons for this statement. Empirical analysis. The paper examines the practice of expert research into submachine guns, that are structurally similar to the 9 mm K6-92 submachine gun (Armenia) and are manufactured as part of criminal arms production, as well as Strelkov submachine guns chambered for 9–18 mm. Individual items had the corresponding weapon attributes (hallmarks, number designations, etc.). The weapon production format, assessed as home-made, is characterized by the choice of simple design schemes, the operation of automation, the prevalence of a cartridge sample, simple manufacturing and assembly techniques, and low quality weapons. Discussion of results. The author proposes introduction of a public law attribute to the system of evaluation criteria of a method for producing firearms – its legitimacy. Its application creates the conditions for covering all cases of the production of firearms known to science and practice, the correct assessment of its method of manufacture, and the selection of an appropriate expert methodology for resolving issues related to classifying an object as a firearm. Conclution. Taking into account the results of the study, there are reasons for supplementing the varieties of improvised firearms known to forensic ballistics with a group of weapons manufactured in industrial plants that are not legalized by central government members. 

 Izv. Saratov Univ. (N. S.), Ser. Economics. Management. Law, 2020, vol. 20, iss. 2
Metrological Aspects of Forensic Ballistic Reserch

Introduction. Conducting forensic ballistic investigations often involve changes to the results of which depend on the findings in many ways. According to local legislation, these measurements must meet certain requirements. Theoretical analysis. Analyzed compliance with the diagnostic techniques of forensic ballistic investigations homemade firing device for assigning it to firearms requirements of the Federal Law «On ensuring the uniformity of measurements». It is shown that the existing methodology is flawed, since it is in contradiction with the current metrological rules are not determined by random and systematic errors. Conclusions. It is proposed to either abandon the statistical processing of the measurement results and not to use the concept of the mean value, or increase the number of measurements for correct statistical treatment of results.

 IZVESTIYA OF SARATOV UNIVERSITY. NEW SERIES. SERIES: ECONOMICS. MANAGEMENT. LAW. 2016. Т. 16, вып. 2