In cases of murder, rape, traffic accidents and in some other cases, hair or fragments belonging to the participants of the incident can be found at the scene of the crime, on the clothing and body of people, on vehicles and other objects. Their study allows you to check the possibility of involvement in a crime of a certain suspect or crime instrument, as well as to clarify the details of the incident.
Detection of hair at the scene and on the evidence is made by inspecting them with the naked eye and using a magnifying glass.
The hairs found during the inspection are described in the protocol of the inspection of the scene of the incident and only after that they are carefully removed. Hair from each item is placed in separate envelopes or bags, on which the corresponding inscriptions are made. They remove hair with fingers or tweezers with rubber or cork tips, at the same time they try not to damage them and to preserve extraneous contaminants.Go
To establish the hair of a particular person - the suspect or the victim, hair samples are taken from him and sent to a forensic expert for comparison. As samples, hair is directed from the frontal, parietal, temporal, and occipital parts of the head (at least 15–20 hairs are taken from each area in the form of a bundle, cutting them off at the base with scissors or pulling them out). If necessary, hair samples can be removed from other parts of the body - pubis, axillary hollows, etc. Hair samples from each area are placed in separate bags or envelopes, on which the corresponding inscriptions are made. When removing hair from living persons, it should be noted whether they have been cut, curled, dyed, discolored, or otherwise exposed or modified from the moment of the incident to the moment of taking the samples. Detection of hair on the body of the abuser or victim of sexual offenses and their removal is made by an expert.
When examining a hair by a medical examiner, the following questions can be solved.
1. Are the sent objects hair?
2. Does the hair belong to a person or an animal (establishing the species of hair)?
3. What part of the body does the hair originate from (regional origin of hair)?
4. Are these hairs dropped or torn out?
5. Is there any damage or changes to the hair - coloring, perm, discoloration?
6. What is the group and gender of hair?
7. Is the origin of hair from a certain person possible? Depending on the circumstances of the incident, other issues may be raised to resolve the expert.
Affiliation of the object under study to the hair is established on the basis of their characteristic structure (morphological picture). In the hair, there is a root (the part of the hair located in the skin) and the stem (the outer part of the hair located above the skin). The root is a hair follicle, it is examined if the hair is torn from the root. The hair shaft is more often studied, in which there are three layers. The outer layer of the hair (cuticle) is a tile-like flat cells located. The cortical layer consists of spindle-shaped cells, in the middle of the hair there is a core. The discovery in the object of study of these three layers allows us to conclude that it is hair. If necessary, other more specific research methods can be applied to solve the issue of the object's belonging to the hair: study of the pattern formed by the free ends of the cuticle cells (for which a hair imprint is prepared on the emulsion layer of a fixed photographic film), the cuticle in the object being examined indicates that he is a hair; production of cross sections of the object (determine the shape of the slice, the presence of the core, the location of the pigment); study of the microelement composition of the hair by the method of emission-spectral studies.
Having established that the sent objects are hair, the expert determines their belonging to a person or an animal, based on the characteristics of their structure (Fig. 96).
The core of a person's hair usually looks like a thin band or individual islands. It is an insignificant part of the thickness of the hair, but the main mass of the human hair is represented by the cortical substance. In animals, the main mass of the hair is the core with a well-pronounced structure. The cortical substance of the animal hair is narrow, the free edges of the cuticle cells are somewhat separated from each other, which under microscopic examination creates the impression of the dentate edge of the hair. The structural features of the cuticle pattern formed by the free edges of the cuticle cells and the core structure allow one to distinguish the hair of animals of different species (Fig. 97).
Fig. 96. Hair, and - man; b - goats; in - rats.
Fig. 97. Hair cuticles. a - fox fox; b - sheep merino; in - North American deer.
The species of the hair can be determined using emission spectral analysis (according to the composition of the elements).