RU2593334C2 - Method for detecting hands traces - Google Patents

Abstract

FIELD: medicine.

SUBSTANCE: invention relates to forensic medicine and can be used for detecting traces of organic origin, in particular, fingers and palms traces. For this purpose, treated with the analysed surface is treated by directed flow of reagent to detect visible coloured traces. Treatment is carried out by aerosol composition containing 0.1-10 % of ninhydrin, 1.0-30.0 % of methyl ethyl ketone or acetone, 1.0-20.0 % of diethyl ether, 0.1-10 % of acetic acid and ethyl or isopropyl alcohol used as ninhydrin solvent. Freon of various grades, propane-butane mix or nitrogen are used as propellant.

EFFECT: invention enables detecting hands traces on various hydrophobic and hydrophilic surfaces.

1 cl, 5 ex

Description

The invention relates to medicine, namely to the field of forensic and forensic medicine, and can be used to identify traces of organic origin, in particular fingerprints and palms.

Methods for detecting and detecting handprints are divided into visual, physical and chemical.

Visual observations are carried out with the naked eye using magnification devices and using various means and methods of lighting. Visually detect tinted, dented, surface marks, layers and delaminations, colorless faded marks on glossy transparent and opaque objects. At the same time, lighting methods play a significant role, the most characteristic of which are based on the use of artificial light sources. Using special lighting sources (for example, an ultraviolet illuminator, a laser), observation of invisible traces is also possible.

Physical methods are based on the ability of substances to maintain adhesive pressure, selective adsorption and the possibility of excitation of luminescence for a certain time.

About 40% of all forensic examinations are expert studies of handprints, which are most often found when examining the scene of incidents. Colorless traces of perspiration remain on the surface of objects, as a rule, at any touch of the fingers. However, such traces will not always be clearly visible and not in all cases they can be made visible using existing forensic technology.

The most common way to detect colorless hand marks is to dust them with powders. This method is simple, does not require complex equipment, is applicable in almost any conditions, and in many cases gives effective results.

Physical methods for detecting handprints also include:

- Dactosols, used mainly to identify handprints on large horizontal surfaces of objects and subsequent work with a fingerprint brush. An example of dactosols is:

a) black SPR atomizer and white SPR atomizer.

Two methods are known for using the SPR preparation to detect traces on the surface of evidence. The surface to be treated is sprayed from a hand sprayer, while taking into account that SPR causes severe surface contamination. Those areas that are not processed should be covered with paper or a napkin. Small material evidence can be processed by immersion in a working solution for 2-3 minutes.

Hand traces detected by SPR appear in dark gray strokes on a light-colored surface and in light gray on dark surfaces. In some cases, traces are poorly visible on the surface until they are transferred to the tracing film. Traces identified using the SPR preparation can be removed on a photocopying film after drying.

b) SPR developer for the detection of traces on wet surfaces. Trace developer SPR (MoS2 molybdenum disulfide) works by the method of physical manifestation, in which small dark particles of the substance are deposited on the fatty components contained in the traces of the hands left on the material evidence. This solution, or rather a suspension, can be successfully used on surfaces such as paper, cardboard, clean and rusty metal, brick, concrete, stone, plastic, wood, galvanized metal and glass. Like other methods for detecting traces, the results are largely dependent on the amount of substance contained in the trace.

SPR Trail Developer is well known for its ability to detect traces on wet surfaces, such as cars in rainy weather or even recovered from water bodies after incidents. When using a sufficiently powerful sprayer, it can be used even under water (with a corresponding increased consumption of useful substance). The SPR trace developer is also applicable in cases where the use of ordinary powders and brushes can ruin the trace.

Physical research methods also include treatment with iodine vapor, based on the selective ability of vapors to penetrate into the trace substance of the trace, staining it in brown. The treatment method using iodine vapor is tried and true in showing marks on paper, cardboard and other paper surfaces. Vapor treatment with iodine is preferable, since iodine reacts to fats and oils that are on the skin and does not react with other chemicals, unlike ninhydrin or silver nitrate.

In addition to the traditional ones described in practice, new physical methods are used:

- autoradiography - the introduction into the substance of a trace of radioactive isotopes with subsequent manifestation (laboratory method);

- an aerosol of cyanoacrylates (for example, Tsiakrin EO). The action is based on a reaction with amino acids and water of a potogyrate substance, causing the polymerization process, staining the trace in white and fixing it on the surface of the object. Cyanoacrylates are commonly used to treat non-porous surfaces.

The closest analogue of the developed invention can be recognized (GB, patent 936092, publ. 04.09.1963) a known method for detecting hand marks. According to the known analogue, it is proposed to use an aerosol composition for detecting fingerprints containing by weight: 0.054% ninhydrin, not more than 3% water, at least 2% acetic acid, not more than 2% dipropylene glycol, 30% isopropyl alcohol, with a combined water content and acetic acid not more than 5%. The method is applicable to detect handprints on paper, unglazed ceramics, starchy clothes and other fibrous materials.

A disadvantage of the known aerosol composition should be recognized as the impossibility of its use on a polymer surface, as well as on a glazed ceramic surface.

The technical problem solved using the developed invention is to expand the range of tools used to identify handprints.

The technical result achieved by the implementation of the developed invention consists in expanding the field of application of the known aerosol composition used in identifying hand traces on other types of surfaces on which it is necessary to identify hand traces.

To achieve the specified technical result, it is proposed to use the developed method for identifying handprints. According to the developed method, the processing of hand traces is carried out by a directed stream of aerosol reagent, through which the traces become visible at a distance, and the reagent used contains (% mass):

Ninhydrin 0.1-10.0 Methyl ethyl ketone Or acetone 1,0-30 Diethyl ether 1,0-20,0 Acetic acid 1.0-10.0 Organic solvent ninhydron - ethyl or isopropyl alcohol Rest

In a preferred embodiment, the treatment is carried out using an aerosol can, with freons of various grades, a propane-butane mixture or nitrogen under pressure are used as a propellant.

The use of ninhydrin solution to detect handprints, including in the form of an aerosol, is quite well known (Forensic Encyclopedia. - M.: Megatron, XXI Belkin RS, 2000). However, the introduction in addition to the composition of the aerosol composition of methyl ethyl ketone or acetone, and diethyl ether allowed to obtain the specified technical result.

The aerosol can is prepared according to the well-known technology (see the book. V. Zeitlin “Aerosol cans”, L .: Chemistry, 1970, p. 34, Fig. 3.1).

The developed method is implemented as follows.

1. The forensic scientist processes the material evidence (jewelry from the list of stolen items seized from the stolen buyer) with a composition containing ninhydrin - 3% by weight, acetone - 14% by weight, diethyl ether - 9% by weight, acetic acid - 4% by weight, ethanol (ninhydrin solvent) - 70% of the mass previously placed in an aerosol can. As the propellant used propane-butane mixture. Spraying was carried out from a distance of 0.20-0.25 m to light moisture. The potogo substances of organic traces of handprints are oxidized, painted, becoming white, and become constantly visible for 3-4 hours. After that, the traces are recorded and seized for further work by forensic specialists.

2. The forensic specialist processes the material evidence (the handle of the knife made of hydrophobic plastic - fluoroplastic -4 seized from the suspect) with a composition containing ninhydrin - 0.1% of the mass, methyl ethyl ketone - 14% of the mass, diethyl ether - 8% of the mass, acid acetic - 3% of the mass, isopropanol (ninhydrin solvent) - 74.9% of the mass, previously placed in an aerosol can. As the propellant used propane-butane mixture. Spraying was carried out from a distance of 0.20-0.25 m to light moisture. Potogo substances of organic traces of handprints are oxidized, painted, becoming white, and become constantly visible within 0.5-2 hours. After that, the traces are recorded and seized for further work by forensic specialists.

3. The forensic scientist processes the material evidence (silicate brick fragment) with a composition containing ninhydrin - 18% mass, acetone - 19% mass, diethyl ether - 11% mass, acetic acid - 5% mass, isopropanol (ninhydrin solvent) - 47% mass previously placed in an aerosol can. As the propellant used propane-butane mixture. Spraying was carried out from a distance of 0.20-0.25 m to light moisture. Potogo substances of organic traces of handprints are oxidized, painted, becoming white, and become constantly visible for 5-6 hours. After that, the traces are recorded and seized for further work by forensic specialists.

4. The forensic scientist processes the material evidence (a piece of viscose silk dress is a hydrophilic polymer) with a composition containing ninhydrin - 8% by weight, methyl ethyl ketone - 27% by weight, diethyl ether - 13% by weight, acetic acid - 5% by weight, isopropanol (solvent ninhydrin) - 48% of the mass previously placed in an aerosol can. As the propellant used propane-butane mixture. Spraying was carried out from a distance of 0.20-0.25 m to light moisture. Potogo substances of organic traces of handprints are oxidized, painted, becoming white, and become constantly visible for 5-6 hours. After that, the traces are recorded and seized for further work by forensic specialists.

5. The forensic scientist processes the evidence (steel open-end wrench) with a composition containing ninhydrin - 1% mass, methyl ethyl ketone - 33% mass, diethyl ether - 16% mass, acetic acid - 5% mass, isopropanol (ninhydrin solvent) - 45 % of the mass previously placed in the aerosol can. As the propellant used propane-butane mixture. Spraying was carried out from a distance of 0.20-0.25 m to light moisture. The potogo substances of organic traces of handprints are oxidized, painted, becoming white, and become constantly visible for 3-4 hours. After that, the traces are recorded and seized for further work by forensic specialists.

The method is applicable for detecting handprints on a pulp and paper carrier, fabric, wood, metal surface, glazed ceramic surface, polymer surface both hydrophobic and hydrophilic.

Claims (2)

1. A method for identifying handprints, including the processing of handprints, characterized in that the handprints are processed by a directed stream of aerosol reagent, through which the footprints become visible at a distance, and the reagent used contains (wt.%):
Ninhydrin 0.1-10.0 Methyl ethyl ketone or acetone 1,0-30 Diethyl ether 1,0-20,0 Acetic acid 1.0-10.0 Organic solvent Ninhydron - Ethyl or isopropyl alcohol Rest 2. The method according to p. 1, characterized in that the treatment is carried out using an aerosol can, while freon of various grades, a propane-butane mixture or nitrogen under pressure are used as a propellant.