SUBMODULE 8.1. FORENSIC IDENTIFICATION OF THE INJURY INSTRUMENT
Identification is establishing sameness of various phenomena, objects and persons according to their individual features.
The theory of forensic identification is based on general principles of objects' sameness by due to manifestations of their features, studied by special scientific methods. Identification of an object used to inflict an injury (injury instrument) is based on the principles of traceology.
Trace evidence analysis is a forensic specialty dealing with laws of trace formation and features indentifying the object that left these traces.
A trace is the changes in the object resulting from its interaction with another object.
In particular, mechanical damage is the trace of injury instrument interacting with a body or clothes. Features of damage allow establishing sameness between the object, which left the traces at the crime scene, and one of possible injury instruments. The traces can be three-dimensional (deformations reflecting the shape and size of the object that left these traces) and superficial (application traces); according to the mechanism of formation, traces can be static (print traces) and dynamic (slip traces).
Identification of the injury instrument is performed by comparing its features reflected in injuries to the body and damage to clothes with the features of the object presented for examination reflected in the traces left in the experiment.
Identification features are properties used to establish sameness.
Common (group) features (weight, shape, chemical composition, degree of blade sharpness, etc.) allow establishing that the identified object belongs to a certain group of objects. Specific (individual) features (deformations, ledges and dents of a certain shape, width, depth and localization) distinguish the object from most or all other objects within the group.