To the question about the use of thermal methods to find out fingerprints on the receipt tape

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TO THE QUESTION ABOUT THE USE OF THERMAL METHODS TO FIND OUT FINGERPRINTS ON THE RECEIPT TAPE

PhD in Law, Associate Professor Irkutsk Law Institute (Branch) of the University of prosecution of the Russian Federation

Yakovlev Gleb Dmitrievish Technician-criminalist of the Department № 10 of the forensic center of the Main Department of the Ministry of internal Affairs of Russia in the Irkutsk region

Abstract

The article discusses the author's method of find out traces of hands on the check tape. The hypothesis of the experiment is presented. The effectiveness of this method is evaluated. It is indicated that failure to comply with the conditions of detection leads to the loss of trace. It is summarized that the use of this technique will allow to identify traces of hands in the detection and investigation of various types of crimes.

Keyword: forensics, daktyloscopy, fingerprints, receipt tape, thermal method.

One of the conditions for the high quality of crime investigation is the wide use in the collection and evaluation of evidence of the latest achievements of science and technology in various fields of expertise. Based on these achievements and using them in their practical activities, employees of the investigative apparatus solve complex crimes, investigate them at a high professional level.

Especially great is the role of science and technology in the collection and expert study of material evidence. The introduction of highly sensitive analytical methods of research into expert practice, the involvement of experts in the field of natural Sciences, who have mastered the methodology of forensic examination, open wide opportunities for in-depth and comprehensive study of numerous material objects.

The greatest difficulty in dealing with material traces of the crime is the identification of traces, since the vast majority of them are latent, i.e. are invisible or invisible.

To date, volumetric Arsenal of various means and methods for the detection of traces of material (including and potozhirovyh), but to talk about the universality of their application is not possible [1, 68-107]. The type and condition of the surface of the object-the carrier, the characteristics of the material from which it is made, the amount of fat remaining after direct contact - this is not a complete list of factors that influence the choice of a specific method of identifying fingerprints.

In addition to traditional objects made of metal, glass, paper, wood, etc. at the crime scene there are objects made of thermochemical tape (check paper). Depending on the type of thermal paper produced, the products may differ in a number of specific characteristics. For example: the number of layers, printing method, width and outer diameter of the roller, the inner diameter of the sleeve.

The main difference from other manufactured paper and pulp products, which is used to display the typewritten text, is the presence of a resistive thermoactive layer-a coating that is applied to one of the sides in the production of thermochemical tape.

The presence of this layer gives the check paper some special properties that affect the mechanism of trace formation and, consequently, on the features of the detection of the trace.

Based on the above, we have proposed the following method of identifying traces of fingers.

The essence of the method is reduced to a uniform heating of the thermochemical tape with traces of the fluidized matter by a flat heating surface for a certain time.

In contrast to the use of chemical methods to detect traces of human hands, this method, subject to temperature, is safe for the thermoactive layer, which is covered with paper, which reduces the risk of damage to the latter to a minimum.

The recommended temperature conditions when working with a thermosetting layer are: 60-100 degrees Celsius. This is due to the fact that, in this temperature segment, the thermal paper begins the process of manifestation.

The strength and degree of thermal impact, before the study should be checked on the experimental object.

In case of exceeding the above temperature regime, the blackening of the thermoactive layer occurs, which leads to the loss of the displayed trace and, accordingly, criminally significant information (Fig.1).

Figure 1. The residual deformation of the thermo layer

During the experiment, it was empirically found that when exposed to different types of thermochemical tape, in the same temperature range, the degree of contrast of the detected handprints can vary from slightly visible to confidently contrasting.

In accordance with this, it is advisable to use graphic editors for color correction in order to minimize the risks of repeated thermal effects on the object under study (Fig.2.3).

Figure 2. The revealed traces of fingers on the thermal tape before color correction

Figure 3. The revealed traces of fingers on the thermochemical tape after color correction in the graphic editor

Figure 4. The result of the application of the thermal method of identifying traces of fingers

trace hand crime finger

Technically, the method is implemented by direct thermal effects on the object under study for 5-10 seconds. To do this, it is necessary to prepare 8 sheets of pure non-laminated A4 paper, place the object under the specified paper sheets and perform heat treatment in the specified time range (Fig. 4). Figure 4. The result of the application of the thermal method of identifying traces of fingers

Another feature of the thermochemical tape after its processing by means of thermal action is its ability to preserve on its surface the identified traces of hands, without their complete or partial destruction.

This is due to the fact that after exposure, potozhirovye traces under the influence of high temperature, securely fixed on the thermosetting layer, without losing its contrast after the manifestation, becoming immune to external influences, such as:

-directed mechanical action on the surface of the thermoactivated tape (friction, sliding, etc.).);

-high humidity in the environment where the object is located, or accidental contact with the surface of the thermochemical moisture tape;

-exposure to ultraviolet rays when exposed to direct sunlight.

These properties of thermochemical tape, as the object of study, allow to exclude the loss of criminally significant information in case of incorrect packaging or transportation of material evidence, as well as provides an opportunity for unhindered research work after a long time.

Undoubtedly, the use of the described method is safer, more practical and does not require special technical support.

It should be borne in mind that, as with other methods of detecting traces of papillary lines on the surface of pulp and paper objects of the investigators, the further result depends on numerous factors, such as:

-the time interval between the contact of the person with the object under study;

-strength and degree of tactile contact with the object;

-condition of the skin;

-the degree of allocation otogirisou substances; -the nature of mechanical action (static, dynamic, etc.).

Bibliography

1. Ekspert. Rukovodstvo dlya ekspertov organov vnutrennikh del / pod. red. d.yu.n. prof. T.V. Averiano- voy. k.yu.n. V.F. Statkusa. - M.: KnoRus. Pravo i za- kon. - 2003. - 592 s.

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