Types of arc patterns. Types and types of papillary patterns

Depending on the structure of the central pattern, the papillary patterns of the fingers are divided into three types: arc, loop, curl.

In arc patterns, the papillary lines of the central flow begin on one side, rise from the middle part, and end on the other side of the finger. In most cases, the delta in the arc pattern cannot be distinguished.

Each type of pattern is divided into types.

Arc patterns on: simple, pyramidal, tent, fir-tree and patterns with an indefinite structure of the central part.

Loop patterns on: simple, half, closed, curved, parallel and double.

Curl patterns on: simple, spiral loops, spirals, snail loops, ball loops, incomplete curl patterns.

The most complex is the curl pattern, and the simplest is the arc pattern.

Such a classification of papillary patterns makes it possible to identify a person by them. Identification tasks are solved by comparing a set of features, fingerprints found during the inspection of the scene and control prints obtained from the suspect or the accused.

In accordance with the classification adopted in forensic science, in each papillary pattern, general and particular signs of its external structure can be distinguished. General features characterize the pattern or its separate relatively large element as a whole, while particular features are related to smaller details of the pattern structure.

The general features of the structure of the papillary pattern include:

a) type and type of papillary pattern;

b) the structure of the central part of the pattern;

c) the position of a part of the pattern;

d) structure and position of deltas;

e) steepness of arcuate lines;

e) width and frequency of papillary lines.

Private features include:

a) details of the papillary pattern (beginning and end of papillary lines, merging and branching of papillary lines, interpapillary lines, short papillary lines and dots);

b) combinations of details of the papillary pattern (the details listed above can be in the pattern not only in isolation, but also in groups, forming certain combinations, sometimes complex and unusual, in a small area or even a segment of one papillary line);

c) details of the papillary lines (these are the features inherent in the papillary lines themselves in the form of breaks, bends, kinks, thickenings, thickenings, edge configurations, as well as the locations and features of the pores).

Fingerprints are currently classified on various grounds, depending on the conditions in which trace formation occurs.

Fingerprints, depending on the conditions in which a person finds himself when committing a crime, are voluminous and superficial. Volumetric ones are formed from a hand touching a plastic trace-receiving surface (plasticine, oil, etc.), and surface ones appear on solid surfaces.

Visible traces of layers are formed due to the presence of a layer of coloring matter (blood, paint, etc.) on the surface of the hands.

Hardly visible traces-layers occur due to sweat-fat secretions of the skin on hard surfaces that do not absorb the substance of the trace, such as glass, porcelain, metal, plastic, etc.

Detachment marks occur when a hand touches a surface covered, for example, with a thin layer of dust.

Scientific researchers have long been trying to learn how to determine a person's character and other features by fingerprints. In this case, we can say that Russian scientists have succeeded. According to the drawing of papillary lines, they were able to identify the sex and height of a person.

Such discoveries should be of benefit to criminologists. It is possible that fingerprints found at the crime scene can be used to compile a psychological portrait of the offender.

Previous materials:

Subject, methods and system of criminalistics
- The essence and tasks of forensic science, its place in the system of other sciences
  - The object of the science of criminology
  - Relationships of forensic science
- Forensic methods
  - General scientific methods used in forensics
  - Special Methods
- System and basic concepts of forensic science
  - Forensic categories
  - Investigative situation
History of the development of forensic science
- The origin and development of forensic knowledge in pre-revolutionary Russia
  - The origin and development of forensic knowledge in pre-revolutionary Russia - page 2
- The development of forensic science in the Soviet period
  - The development of forensic science in the Soviet period - page 2
- Development of foreign forensics
Forensic identification and diagnostics
- The concept and scientific basis of forensic identification
- Objects and process of forensic identification
  - Objects and process of forensic identification - page 2
- Types of identification studies
- Forensic diagnostics
General theoretical provisions of forensic technology
- System and rules for the use of technical and forensic means
- Classification of technical and forensic means
- Technical and forensic means used in the course of investigative actions
- Technical and forensic tools used for expert research of forensic objects
- The use of technical and forensic tools to solve other forensic problems
Computers as a means of forensic technology
- The value of information and computer support for forensic activities
- Computerization of the crime investigation process
  - Means of automating the investigation of criminal cases
  - Automated fingerprint identification system
- Computerization of expert research
  - Computerization of expert research - page 2
Forensic photography, videotape and holography
- The system and meaning of forensic photography
- Forensic operational photography
  - Photographing during the inspection of the scene
- Forensic research photography
- Forensic videotape
- Forensic holography
  - Forensic holography - page 2
  - Forensic holography - page 3
Forensic Habitoscopy
- Rules for verbal description of a person's appearance
  - Rules for verbal description of a person's appearance - page 2
- Anatomical (morphological) signs of the external structure of a person
  - Eyes
  - cheekbones
  - hairline
  - torso
- Functional signs, special and catchy signs of appearance
- Sources of information about the appearance of a person
- Using the technique of "verbal portrait" in operational-search and investigative practice
  - Using the "verbal portrait" technique in operational-search and investigative practice - page 2
- Photo-portrait expertise
- Identification of a person by genetic characteristics
  - Identification of a person by genetic characteristics - page 2
Traceology
- Classification of traces, rules for their detection and seizure
  - Classification of traces, rules for their detection and seizure - page 2
- Handprints
  - The mechanism of the formation of handprints and methods for their detection
- footprints
- Traces of hacking tools and tools
  - Inspection of broken locks and barriers
  - Fixation of traces
- Vehicle tracks
Materials, substances, products as carriers of forensically significant information
- General provisions and tasks of forensic research of materials, substances and products
- Types and possibilities of forensic research of materials, substances and products
  - Types and possibilities of forensic research of materials, substances and products - page 2
- Forensic investigation of micro-objects
  - Forensic investigation of micro-objects - page 2
  - Forensic investigation of micro-objects - page 3
Forensic odorology
- The concept and classification of odorological objects
- Working with human scent traces
Forensic weapons science
- General provisions of forensic weapons science
  - General provisions of forensic weapons science - page 2
- Classification and information content of ballistic objects
- Classification and characteristics of handguns
  - Ammunition for firearms
  - Traces resulting from the use of firearms
- Detection, inspection, fixation and seizure of firearms and traces of a shot
- Forensic analysis of weapons and traces of their action
Forensic explosives
- General provisions of forensic explosives
- Detection, examination, fixation, removal and examination of explosive objects
Forensic documentation
- The concept, types and tasks of forensic documentation
- The concept and classification of objects under study
- Identification of means and materials used for the production of documents
  - Research of printing materials
- Establishing the presence and method of falsification of documents
  - Establishing the presence and method of falsification of documents - page 2
- Restoration of unreadable records, torn and burned documents, reading encrypted correspondence
- Study of document materials
Forensic investigation of writing and writing
- Scientific foundations of forensic research of writing and writing
  - Scientific basis of forensic research of writing and writing - page 2
- The concept, classification and information content of handwriting features
  - Topographic features of handwriting
  - General signs of handwriting
  - Private signs of handwriting
Forensic phonology
- Scientific foundations of forensic phonology
- Determination of personal qualities of a person on the basis of oral speech
  - Determination of a person's personal qualities on the basis of oral speech - page 2
- Automated methods for analyzing oral speech
Forensic registration
- General provisions of forensic registration
  - Legal basis for the functioning of the forensic registration system
  - Forensic registration system
- Operational reference, search and forensic records
  - Forensic and search records
  - Forensic and search records - page 2
- Forensic accounting
  - Regional forensic records
- Reference and auxiliary accounting
- Forensic information arrays of international organizations
General provisions of forensic tactics
- The concept, essence and categories of forensic tactics
  - Investigative situation
  - tactical operation
  - Tactical decision
  - tactical risk
- Forensic tactics and investigative practice
- Investigative tactics
Forensic leads and investigation planning
- Features of the versioning process in forensics
  - Features of the versioning process in forensics - page 2
- Crime investigation planning
  - Planning methodology
- Planning of individual investigative actions and operational-search activities
  - Planning of individual investigative actions and operational-search activities - page 2
Forensic examination and examination
- The concept and general tactical provisions of the investigative examination
  - Participants of the investigation
- Scene inspection tactics
  - Scene Inspection Tactics - Page 2
- Types of investigative examination
- Certification
Investigative experiment
- General provisions for the production of an investigative experiment
- Preparation for the production of an investigative experiment
- Tactics for the production of an investigative experiment
  - Tactics for the production of an investigative experiment - page 2

Handprints

The branch of traceology that studies handprints is traditionally called fingerprinting (from the Greek daktilos - finger, skopeo - examination). Fingerprinting is a branch of forensic technology that studies the structure of skin patterns on a person's fingers in order to use their traces in order to identify, register and search for criminals. It also includes palmoscopy and plantoscopy, which study the patterns of the palms of the hands and feet of a person. In recent years, forensic dermatoglyphics has begun to take shape, in which fingerprinting has become one of the main parts.

It is known that the relief of the skin is not the same. On the palms (feet of the legs), in addition to ridge-like protrusions called papillary lines and separated by grooves, there are flexor (flexion) lines, wrinkles and folds (white lines), as well as pores. The most noticeable relief elements are flexor lines. White lines (wrinkles) appear due to loss of elasticity and dryness of the skin, as well as age-related changes. These lines usually play an auxiliary role in identification.

The most significant are papillary lines and pores, which have a different shape and are located at different distances from one another and from the edges of the papillary lines. These lines on the palms and nail phalanges of the fingers have a rather complex and diverse structure.

The main properties of the papillary pattern are individuality, stability and recoverability.

Individuality lies in the fact that each person has a pattern pattern that is peculiar only to him. This is due to the peculiarities of the anatomical structure and biological functions of the skin, as well as the genetic originality of a person. Even in identical twins, the set of details of skin patterns never repeats.

For more than a hundred years in the world practice of fingerprinting, not a single case of the coincidence of all the details of the skin pattern in different people has been identified. Details are not repeated on different fingers of one person. According to mathematical calculations, the probability of coincidence of papillary patterns on all ten fingers in two people is vanishingly small, so it can be neglected.

Stability means that papillary lines appear on the 3-4th month of intrauterine development of a person and persist until the complete putrefactive decomposition of the skin. With the growth of the organism, only the dimensional characteristics change, but not the patterns themselves.

Restorability guarantees complete renewal of the pattern in case of damage to the upper layer of the skin (epidermis). With a deep injury to the dermis (skin itself), scars or scars are formed, which even increase the number of individualizing signs.

An important characteristic of the skin is the ability to be displayed on those objects that a person has touched. The formation of fingerprints, palms, feet occurs regardless of his will and desire, since it is due to the physiological properties of the skin: its surface is always covered with sweat-fat secretions, which stick to trace-receiving surfaces.

To date, about 30 amino acids have been discovered that are present in the sweat fat substance. Their set for each person is individual, and besides, their ratios in a particular individual are distinguished by a noticeable originality. It is on this that the method of identifying a person by the amino acid composition of his sweat-fat substance is built.

Moreover, its biochemical studies allow obtaining information about the blood group, gender, certain diseases of the body, especially those associated with the immune system, medications taken, drugs, habitual food, etc. This significantly narrows the circle of suspects among whom it is necessary to search for the criminal.

The papillary patterns of the nail phalanges are formed by three papillary streams: center lines, peripheral lines and basic lines. The part of the pattern where these streams meet forms a characteristic area called the delta, since it looks like this letter of the Greek alphabet.

Papillary patterns of the nail phalanges of the fingers are divided into types and types depending on the pattern of their center. On this basis, three types of patterns are distinguished: arc, loop and curl.

Loop patterns are the most common - 65% of the total. Curl patterns are about 30%, and arc patterns are about 5%. Each type of pattern has varieties depending on the structural features of the central part. So, arc patterns can be simple, hipped, etc.

Loop patterns are distinguished by the direction of the legs of the loop and the structure of the latter. In the direction of the legs, the loop patterns are divided into radial (the legs are turned towards the thumb) and ulnar (the legs of the loop are turned towards the little finger). Depending on the structure of the loop, the patterns are simple, half-hearted, curved, closed, etc.

Curl patterns are simple: circular, oval, spiral (complex spiral, double helix), (homogeneous and heterogeneous) and complex.

In the arc pattern, there is usually no delta, since it is formed by only two streams. In the loop pattern there is one, and in the curl pattern there are two or more deltas. By this feature (the number of deltas), it is easiest to distinguish patterns.

Types and types of papillary patterns, the size of papillary lines, the degree of their curvature, the outline of flexor and white lines are common features.

Particular features of the papillary pattern used for individual identification are individual features in the structure of each specific papillary line, its small morphological differences are details. These include eyes, islands, hooks, bridges, fragments, bifurcations (forks), the beginning of lines, scars, pores, ruptures, bends, thickenings, features of deltas, dots, merging papillary lines and their fragments.

For individual identification in the compared traces, it is necessary to identify a unique set of matching particular features.

Fingerprinting (from the Greek Daktylos - finger and skopeo - I look) studies the properties and structure of human skin patterns. The palms and feet of a person are covered with papillary patterns. Because of their properties, they are of high value as evidence.

papillary lines - linear elevations, very small in width and height, bending, form complex structures and patterns of various shapes (papillary patterns), are located along the entire palmar surface and are separated by small grooves. They have the greatest identification value in handprints.

Let us consider traceologically important properties of papillary lines of human hands.

Individuality - each papillary pattern has the features of the pattern that are inherent in one particular person. The coincidence of papillary patterns in different people, as well as in the same person on different fingers, is excluded.
Stability - the papillary pattern is formed during fetal development, over time, only the size changes, but not the details of the pattern.
Restorability - after damage to the epidermis (upper skin), the papillary pattern is restored.

Signs of papillary patterns are divided into general and particular (details).

Common signs are divided into the following types of patterns.

arc patterns are formed by an external flow of papillary lines and in the middle part of the pattern have a bend - an inner arc, the structure and shape of which serve to divide them into types: simple and tented;

Loop patterns consist of external and internal flows of papillary lines and have one delta. They are formed by an internal stream, the papillary lines of which, starting at one edge of the finger, bend upward and towards the center and, forming a loop, return to the same edge. The loop pattern consists of a series of loops located one inside the other, but to classify the pattern as a loop type, it is necessary that at least one line in the center of the pattern forms a complete loop head or a complete loop.

The most concave part of the central loop is called hinge head, the rest - her legs: the upper point of the loop head, dividing it into two equal parts, - top of the loop. The inner loop can have a complex structure due to the inclusion of individual lines, fragments, dots.

Types: depending on the construction of the loop: simple, half, curved, closed

Depending on the direction of the legs, the loops are radial (legs towards the thumb, ulnar (legs towards the little finger)

Curl patterns consist of external and internal flows of papillary lines and have two deltas (less often - three or more). They are formed by an internal flow, the papillary lines of which in the middle part are curved in the form of circles, ovals, spirals, flows that envelop each other or form different combinations. Types: circular, oval, spiral, ball, etc.

Previous materials:

Traces of human hands are found at the scene much more often than any other traces. These traces are of great forensic significance, since they contain information that can be used to identify a specific person, about the personality traits of the participants in the event under study and some of its circumstances.

Ways to detect handprints

Methods for identifying and detecting handprints can be divided into visual-optical, physical and chemical. Often, the methods are classified into visual-optical, physical, chemical, physico-chemical and microbiological.

Visual-optical methods

Visual-optical methods for detecting traces are based on the observation of specific differences in the interaction of the surface of an object with the light of the trace itself: total or spectral absorption or reflection, scattering, refraction, shadowing and radiation (luminescence). A specific optical method consists in a certain combination of the method of illumination and observation in order to obtain the greatest difference in the contrast of the trace and the surface of the object (with radiation - color), where the choice of angles of view and illumination is important.

Visual-optical methods are used to detect volumetric, colored or hardly visible traces. These methods are based on enhancing contrast by creating favorable lighting and observation conditions. These methods include: examining objects with the “naked eye” from different angles of view or transparent objects through the light or using optical magnification devices (loupe, microscope), lighting ( lamps, lanterns), as well as using a laser, sources of ultraviolet rays, light filters.

The advantages of these methods are simplicity, accessibility and rationality, since they do not lead to the violation of either traces or surfaces of perceiving objects and therefore should be used in the first place.

Physical methods

They are based on the properties of adhesion (attraction) and selective adsorption (absorption) of the trace substance and the possibility of excitation of its own luminescence (glow).

Fingerprint powders

Processing with fingerprint powders is the main and most common way to detect faintly visible and invisible surface handprints on various surfaces.

This method consists in mechanical coloring of the surfaces of objects with powders that differ in structure (fine, coarse), in specific gravity (light and heavy), in color (light, dark, neutral), in magnetism (magnetic and non-magnetic), in composition ( single-component and mixtures, fluorescent and phosphorescent).

When working with powders, the following conditions must be observed: the surface of the object to be treated with powder must be dry and not sticky; powders should be dry and fine, contrasting with the treated surface. All powders are used to detect fresh handprints.

Powders are applied to the surface of a trace-perceiving object in one of several ways:

a) bulk (rolling the powder over the surface of the object under study);

b) using a fluffy brush, fiberglass or magnetic brush;

c) using aerosol dispensers, "air mills".

The main disadvantages of the method:

short detection time, up to 20 days;
contamination of the tracker, which makes it difficult to study it later;
the use of this method on porous objects excludes the subsequent use of iodine, ninhydrin, silver nitrate and its mixture with iodine.

When working with powders, it is necessary to protect the respiratory organs - use a gauze bandage or a disposable respirator.

Method of ultraviolet and infrared rays

This method is used to detect old and invisible traces on multicolored objects; it is universal, i.e. can be applied both at the scene (if the necessary equipment is available) and in the laboratory.

Ultraviolet rays reveal invisible and slightly visible handprints formed by various mineral and vegetable oils, glue, blood, as well as traces processed with luminescent fingerprint powders. In infrared rays, it is possible to detect faintly visible traces and traces of hands stained with soot (soot).

First, the surface to be examined is treated with fluorescent substances (special luminescent fingerprint powders) that penetrate into the trace and luminesce in ultraviolet rays. If luminescence is observed in ultraviolet rays of both the object and the trace, then the trace is photographed in infrared rays after preliminary treatment of the surface of the object with graphite powder, which is opaque to infrared rays. Handprints revealed in this way can be recorded using photography.

digging

Footprint digging is used to reveal handprints on polished surfaces. Its essence is as follows: when burning individual objects (for example, casts made using K paste, polystyrene foam, camphor, naphthalene, pine torch, etc.), soot will be abundantly released, which is a fine powder, which colors sweat hand trace.

Using Physical Developers

For this method, molybdenum disulfide (MoS2) is used - the most famous of foreign aerosols is SPR (Small Particle Reagent). In practice, dark (SPR1OO-Black), white (SPR200-White) and fluorescent (SPR400-UV) aerosol suspensions are used. The essence of the method is that small dark particles of molybdenum disulfide (a physical finely dispersed developer) are deposited on the fatty components contained in the traces. Physical developers detect marks on wet surfaces, surfaces covered with sediments (salt, dirt, grease), such as surfaces, cars in rainy weather or objects removed from bodies of water, where the use of conventional fingerprint powders and brushes can ruin the mark. The finely dispersed suspension works well on dry surfaces, as well as on surfaces that are “difficult” for powders: greasy glass, reinforced concrete, brick, stone, wood, rough and rusty galvanized iron and galvanized metals. SPR can be used on paper, cardboard, wax coatings, plastics, metal, glass, packaging materials. With a powerful atomizer, the SPR can be used underwater.

Surfaces are sprayed from a hand sprayer, and small objects are immersed in the working solution for 2-3 minutes. Then, using a spray bottle with clean water, the identified traces are rinsed, and the moisture is removed (it is not recommended to use a hair dryer to dry the traces). Handprints are revealed in dark gray strokes on a light surface and in light gray strokes on a dark one. Individual traces may be poorly visible on the surface before removal to the trace film. With a solution of molybdenum disulfide, it is possible to process handprints identified by ninhydrin to enhance their contrast. The method also makes it possible to detect traces not detected by ninhydrin. In low concentrations, the molybdenum reagent enhances the traces identified by silver nitrate, which is especially important for "old" traces.

The shelf life of the working qualities of the solution is about four weeks. The shelf life of the aerosol is one year.

The disadvantages of using SPR are: the formation of difficult-to-remove dirty marks when the SPR working substance is left on the treated surface for several months, as well as the fact that the treatment of marks on dry surfaces is inferior to the treatment with powders. The above products are not poisonous, but they are not recommended for indoor or outdoor use where property damage may occur. SPRs are highly contaminating agents and require rinsing with water to remove any residual reagent before photographing and removing the identified traces. The room where they are supposed to be used must be ventilated. It is recommended to use rubber gloves, gauze bandage (disposable respirator) and goggles when working with SPR.

Fumigation with iodine vapor

This method can be attributed to physicochemical methods. It is based on the physical adsorption of iodine vapor on the sweat-fat substance of the trace and its chemical reaction with saturated fatty acids, staining the traces brown.

The advantage of this method is that traces can be processed several times. The disadvantage is that the traces quickly disappear and become invisible.

Crystalline iodine - grayish-black plates with a metallic sheen or intergrowths of crystals with a characteristic odor. Volatile at ordinary temperature, when heated, it actively sublimates, forming vapors. Slightly soluble in water.

Obtaining iodine vapor is possible in two ways:

1. "cold" way. Iodine crystals sublime at room temperature. To do this, the object is brought into contact with glass, on which there is a thin layer of small iodine crystals, or placed in a vessel with iodine crystals at the bottom;

2. "hot" way. Vapors are obtained by heating iodine crystals in a sand bath, spirit lamp, in special apparatus with an electric heating method, etc.

Processing of an object with alleged traces can be done in various ways, the most common of them:

movement of an object over a container (plastic bag, deep dishes) filled with iodine vapor (it is advisable to use a transparent container to control the detection of traces);
placing the object in a container with iodine vapor (if the surface is completely immersed);
movement on the surface of the funnel object (preferably transparent), filled with iodine vapor;
imposition on the surface of an object of an even flat object (for example, clean and dry glass), previously treated with iodine vapor, while the tighter the contact, the better the detection of traces (the neck of the jar in which iodine evaporates is closed with flat glass). After some time, the smallest crystals of iodine are deposited on the glass. This side of the glass is superimposed on the surface where traces are expected. Iodine from the glass passes to the sweat-fat substance and stains the traces;
the use of special iodine tubes of various configurations.

Iodine vapor is produced by passing a jet of air at room temperature through the tube. During operation, the tube is clamped in the hand, the heat of which ensures the transition of crystalline iodine to a gaseous state. Iodine vapor is blown out towards the surface where colorless handprints are expected. With the help of an iodine tube, sweat-fat traces of hands are found on surfaces of any shape.

It should be noted especially that with iodine vapor it is possible to reveal fresh (up to two hours old) traces of hands on the skin of a corpse. To do this, the skin of the corpse is fumigated with iodine vapor using a wide funnel. The removal of traces of hands fumigated with iodine vapor from the human body can be carried out by contact and on silver plates (or less expensive copper plates galvanized with silver) with increased contrast of traces under the action of bright lighting. On such plates, up to four copies can be made from one fumigated trace with a change in the contact time of the plate with the trace. At the time of fixation, the mark should have a light brown tint on the yellow surface of the skin. As a result of using an incandescent lamp for 1-2 minutes, the marks may darken, up to a purple color. The identified traces lose their color after 15-20 minutes, therefore they should be photographed or fixed on the surface of the object with iron powder reduced by hydrogen (carbonyl iron), starch solution, dactolin, iodocopy paper (impregnated with 2% orthotolidine solution).

Iodine is dangerous when inhaled, volatile, causes burns of the respiratory tract, mucous membranes, if ingested - severe burns of the gastrointestinal tract, lethal dose - 3 g.

Chemical methods

Chemical methods are based on a chemical reaction between the components of the trace fatty substance and special reagents that cause their staining or luminescence. They are carried out, as a rule, in laboratory conditions, allow to identify traces of great age and exclude the subsequent biomedical study of the substance of the trace.

Since chemicals change the original appearance of the object, it is recommended to use them in the process of inspecting the scene in exceptional cases.

Ninhydrin

Ninhydrin (triketohydrindenhydrate; 2,2-dihydroxy-1,3-indan-dione) is a white crystalline powder, one of the best chemical reagents for detecting handprints on porous and rough surfaces, on paper and cardboard, traces on planed and unpainted wood, on fabrics. It interacts with a-amino groups of amino acids, peptides, proteins, sweat-fat substances, staining them in pink-violet color (Ruemann's purple). The use of ninhydrin makes it possible to detect traces of very long prescription (up to 10-15 years).

In practice, various solutions of ninhydrin are used - in acetone, ethanol, petroleum ether, in a multicomponent solution based on HFE-7100, pyridine, ethyl ether, methanol, fluorisole, etc.). Mainly applied 2-5% solution of ninhydrin in acetone, for the preparation of which it is necessary to mix 2-5 g of crystalline ninhydrin and 98-95 g of acetone. To prepare a 2-5% solution of ninhydrin in ethanol (ethyl alcohol), it is necessary to mix 2-5 g of crystalline ninhydrin and 98-95 g of ethanol. The solutions are stirred until the crystalline precipitate is completely dissolved, and should have a transparent yellow color. Please note that the above solutions can dissolve various dyes (ballpoint pen ink, gel pen ink, printing ink, etc.), so if documents are processed, the content of which is important, then processing must be done with extreme caution or a less aggressive solution should be selected .

A characteristic feature of these multicomponent solutions is that the processed document undergoes minimal changes, since not a single dye is practically washed out (including ink, seals and stamps) and the substrate of the object is practically not stained.

The reaction with ninhydrin proceeds well in conditions of high humidity, the best results are achieved with humidity The appearance of traces begins after 20-30 minutes, and within 4-6 hours they become bright purple in color, however, some "old" traces are detected on the surface very slowly gradually - up to 10-14 days from the date of processing.

The chemical activity of ninhydrin continues after the treatment of the object, which, when touched, leads to staining of hands and documents.

If necessary, traces from the object can be removed by wetting with a 15% hydrogen peroxide solution or a saturated sodium thiosulfate solution.

Disadvantages: ninhydrin is relatively easy to decompose during storage and its quality must be periodically checked on control traces; traces found on dark and colored surfaces are poorly distinguishable; the method is designed to detect no more than 60-80% of handprints on the object and is not suitable for objects that have been moistened due to leaching of chlorides. The enzyme quickly loses activity, so it must be stored in a cool, dry place. Traces kept in iodine vapor for more than 10 minutes, and then detected with ninhydrin, have a weaker luminescence after treatment with metal salts compared to untreated with iodine. Fixation of handprints identified by iodine with benzoflavon does not affect their reaction with ninhydrin and may increase their contrast. In some cases, an increase in luminescence is observed after the treatment of traces of hands with metal salts, which were first identified with iodine and fixed with benzoflavon, and then treated with ninhydrin. Re-treatment of traces of hands identified by ninhydrin with zinc or cadmium salts changes their color due to the formation of a luminescent complex when excited by a laser or argon lamp. The quality of the detected traces, especially on texts or painted surfaces, is improved.

The prepared solution of ninhydrin in a spray can is sprayed evenly onto the surface of the object. The spray can should be kept at a distance of 10-15 cm from the surface of the object. After processing, the object is dried in a fume hood. The reaction in room conditions takes about 24 hours, and in some cases - 2-3 days - the traces turn purple. When processing objects that are coated with dyes that are sensitive to solvents (for example, ballpoint pen paste, print impression, etc.), it is most effective to use special ninhydrin solutions. If this is not possible, then the following method can be applied: a blank sheet of paper is impregnated with a solution of ninhydrin, after which this sheet is superimposed on the surface with traces and ironed on top with a hot iron. The same method is used to detect traces on the surface of objects such as plaster, whitewashed wall, building bricks.

To speed up the reaction, an express processing method is used: the object is placed in a ninhydrin chamber at a temperature of 80-115°C. Under these conditions, the trace is painted after 15-20 minutes. Traces on cardboard, plywood, wood for greater contrast can be treated twice with ninhydrin or the concentration of the latter can be increased to 2-5%. Further manifestation of the trace is carried out in normal room conditions or with the use of heat sources.

The traces revealed by ninhydrin do not lose their contrast for several years. If it is necessary to preserve traces, then in this case the ninhydrin that has penetrated the thickness of the paper should be neutralized. Otherwise, subsequent touching of the document with unprotected hands may stain the resulting skin marks. The surface of the examined document is wetted with this solution. In this case, the identified traces of purple ninhydrin turn red. A change in the color of the traces is a sign of the complete neutralization of ninhydrin.

Nitrate silver

Silver nitrate (AgN03 lapis) - the method is photochemical in nature, based on the interaction with salts of sodium chloride and potassium chloride of the fat substance and is used to detect handprints on paper, cardboard, plywood, unpainted wood up to one month old (in some cases - up to six months) sometimes on fabrics.

In practice, 1-10% solutions are usually used (in various solvents). As a result of the reaction, silver chloride is formed, which, under the influence of sunlight or ultraviolet rays, easily decomposes and turns into metallic silver, which colors the skin pattern displayed in the trace in a dark brown (up to black) color.

Most often, a 5-10% solution of silver nitrate in distilled water is used, or from 0.5 to 5 g of silver nitrate, 1 g of citric acid, 0.5 tartaric acid are dissolved in 100 ml of distilled water and 3-5 drops of concentrated nitric acid.

The solution is applied to the surface with a spray gun, a cotton swab, or the object is immersed in a solution of silver nitrate. For fresh traces, a less concentrated solution is used. Fixing the identified traces is carried out with a solution of sodium hydrosulfate.

The process of detecting traces can be accelerated by irradiating the treated object with ultraviolet rays until the trace appears. After a few days, the traces that appear become indistinct and unsuitable for identification due to the darkening of the general background, so the identified traces are immediately photographed.

Silver nitrate is used to enhance the traces of hands identified by ninhydrin, for which a solution - 0.3 g of silver nitrate 100 ml of ethyl alcohol - is applied to weakly identified traces with a cotton swab and exposed to light. With a combination of methods for detecting traces, silver nitrate can only be used after the use of ninhydrin.

Alloxan

A 1-1.5% solution of alloxan in acetone or alcohol is used. The marks turn orange and have a bright crimson glow in ultraviolet light. Traces appear in a time from 2 hours to 1-2 days.

A solution of benzidine in alcohol with hydrogen peroxide

A solution of benzidine in alcohol with hydrogen peroxide (five parts of a 0.1% solution of benzidine in alcohol and one part of 3% hydrogen peroxide) is used to detect handprints formed by layering of blood. Blood traces treated with this solution turn blue-green. The color is stable and does not require additional fixing.

Luminol

Luminol - an aqueous solution of 3-aminophthalhydrazite and sodium carbonate (in a ratio of 0.14: 0.2), is used to identify and diagnose hand marks formed by blood, vegetable and fruit juices, as well as some paints and metal powders.

Surface treatment is carried out by spraying in a darkened room and leads to a short-term glow of traces. It should be borne in mind that when using luminol, the luminescence of blood or metals is not differentiated, and the possibility of a subsequent biological study of traces formed by blood is also excluded.

Ardrox

Ardrox is a reagent for traces on non-porous plastic surfaces and PVC materials. It is used both in pure form and in solution with sequential mixing of 10 ml of Ardrox concentrate + 20 ml of acetonitrile + 980 ml of isopropyl alcohol (as well as in methanol, ethanol). Two minutes after spraying, the object is washed with water and dried. Yellow-green luminescence traces are observed in ultraviolet rays (UFL) at a wavelength of 350-365 nm, the best results are achieved at a wavelength of 450-480 nm.

Rhodamine

Rhodamine 6G (Rhodamine 6G) - a saturated solution in methanol, diluted four times with freon.

Luminescence is observed at a wavelength of 514.5 nm in the beams of an argon-krypton laser. It is one of the best laser dyes. Can be diluted in methanol, a simple solvent or water and used on metal, glass, leather, plastic and more.

Illustrations for methods for detecting handprints

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Methods for fixing and removing fingerprints

Traces of hands found (revealed) at the scene of the incident must be recorded. The main method of fixation is the description of the traces in the protocol of the inspection of the scene, additional - photographing; drawing up schematic sketches, diagrams, plans; fixing the trace on the object; trace copying.

In the most general form, the description of handprints in the protocol can be carried out according to the following scheme: characteristics of the object on which traces were found, its name, location, state of the object itself and its surface; individual features of the item (number, marking); method of detecting traces, quantity, shape, size, location on the object and relative position; the type of each trace (superficial, volumetric, fat-fat - hardly visible, invisible, if colored, then its color); type of papillary pattern (curl, loop, arc); whether the traces were processed, if so, how; whether photographs of handprints were made; methods of removing the trace (object), the color and dimensions of the trace copy film on which the traces were withdrawn; how the trace was packed (characteristic of the material), the content of the inscription made on the packaging and what seal it was sealed with.

If possible, an object with traces of hands is removed in kind, and if it is impossible to do this, the traces are fixed by copying, i.e. transferring them to a trace copy film. Depending on the color of the powder used to detect traces, a special trace copying black (for light powders) or a transparent film (for black powders) is used. It consists of two sheets of celluloid, on one of which (the main one) a copying mass is applied. The other sheet is protective, it protects the copy mass from drying out during film storage; after copying the trace, the protective layer is again superimposed on the main one and protects the copy from damage.

Direct fixing of traces on the object is carried out with the help of aerosols (hairspray, etc.); traces treated with iodine vapor, as noted above, are fixed with iron powder reduced by hydrogen.

Contact copying of traces is carried out on: sticky tapes; fixed soaked photo paper; medical adhesive plaster; insulating tape; vulcanized rubber; polymer materials (trace copying tool "Copy"); traces treated with iodine vapor can be copied onto self-coloring film or paper.

The production of casts from volumetric traces of hands is carried out using various synthetic materials (pastes, solutions, mixtures).

	Loopback	Curlic
Simple single hinge curved hinge closed hinge half hinge	Simple simple circle simple oval simple spiral loop-spiral
Difficult: hipped with indefinite center	Difficult: parallel loops counter loops
False: false loop arc false whorl arc rare, related to arc	False: false-curl loop rare, related to loop	False: rare, related to whorls
Abnormal According to the ten-finger fingerprint classification, abnormal papillary patterns are equated to arc ones and are indicated by the number 1

Arc patterns are formed by an external flow of papillary lines and in the middle part of the pattern have a bend - an inner arc, the structure and shape of which serve to divide them into species.

Rice. nine.

1 - simple arc pattern; 2 - tent arc pattern; 3 - an arc pattern with an indefinite structure of the center; 4, 5 - false-loop arc patterns; 6, 7 - false-curl arc patterns; 8 - a rare pattern related to arc; 9-anomalous pattern (classified, like arcs, by the number 1).

The types of arc patterns include the following (Fig. 9): simple arc patterns - papillary lines form a small, relatively smooth rise in the middle part of the pattern;

hip arc patterns - papillary lines form a sharp bend in the middle part with several vertical lines in the middle. A variety of tent patterns are fir-tree and pyramidal arcs;

arc patterns with an indefinite center structure - papillary lines in the inner part of the arc form a kind of indefinite pattern that does not allow it to be attributed to other types of arc patterns;

false-loop arc patterns - papillary lines in the inner part of the arc form a pattern that resembles a loop in its external structure, but is not one. There are three cases of determining the falsity of patterns:

a) two lines converging at an angle into one do not form a semicircular head, characteristic of loop patterns;
b) two lines converging at an angle continue as one, without forming a loop head; between them there may be one or more lines that enhance the effect of falsity;
c) the head of the inner loop merges with the line that is part of the outer flow and goes into it, bypassing the false delta;

false-curl arc patterns - papillary lines in the inner part of the arc form a pattern that looks like a curl, but it lacks features that determine the curl types of patterns;

rare patterns related to arcs - papillary patterns of loops-balls and curved loops, the heads of which are located at the very edge of the pattern (near the nail), and the central part has an arc-type pattern; are not displayed on the fingerprint card with a slight underrolling of the fingers;

abnormal pattern - the papillary lines of the internal flow outwardly resemble a loop pattern, but none of the lines of the loop forms; they merge at an acute angle at the top of the pattern or "go" up (towards the nail). Abnormal patterns are classified as arc patterns.

Loop patterns consist of external and internal flows of papillary lines and have one delta. They are formed by an internal stream, the papillary lines of which, starting at one edge of the finger, bend upward and towards the center and, forming a loop, return to the same edge. The loop pattern consists of a series of loops located one inside the other, but to classify the pattern as a loop type, it is necessary that at least one line in the center of the pattern forms a complete loop head or a complete loop.

The most concave part of the central loop is called the loop head, the rest is called its legs: the upper point of the loop head, dividing it into two equal parts, is the top of the loop. The inner loop can have a complex structure due to the inclusion of individual lines, fragments, dots.

Rice. 10.

1 - simple loop pattern; 2 - curved loop pattern; 3 - half loop pattern; 4 - closed loop pattern "racket loop"; 5 - loop pattern with a system of loops "parallel loops"; 6 - loop pattern with a system of loops "counter loops"; 7, 8 - false-curl loop patterns; 9 - a rare pattern related to the loop.

Depending on the shape of the loops, the mutual arrangement of the legs of the loops and the position of the loops in the plane of the internal flow, they are divided into types (Fig. 10):

simple loop patterns - papillary lines form a central pattern, which is a typical loop (the head has a semicircular shape, the legs are relatively straight parallel lines);

curved loop patterns - the papillary lines that form the loop head (and do not have a second delta in the loop head area) are curved towards the base of the pattern. If the loop head is lowered to the base of the pattern and located between two deltas, the type of pattern is defined as a whorl;

half-loop patterns - the legs of one or more loops that enter one another, merge into one line on one side;

closed loop patterns - the legs of one or more loops that enter one another merge with each other and are on the same papillary line located in the inner loop (“racquet loop”);

parallel loop patterns (parallel loops) - the internal flow of the pattern consists of two independent loops located parallel to each other;

counter loop patterns (counter loops) - the internal flow of the pattern consists of two independent loops, located with their heads to the center of the pattern, and legs - to its opposite edges;

false-curl loop patterns - the papillary lines of the internal flow form a pattern that looks like a whorl, but does not have signs of closed and half loops, and also does not form a circle, oval or loop-tangle system;

rare patterns related to loops - papillary lines of loops-balls and curved loops, the heads of which are located at the very edge of the pattern (near the nail), and the central part has a loop-type pattern; are not displayed on the fingerprint card with a slight underrolling of the fingers.

Curl patterns consist of external and internal flows of papillary lines and have two deltas (rarely three or more). They are formed by an internal flow, the papillary lines of which in the middle part are curved in the form of circles, ovals, spirals, flows that envelop each other or form different combinations.

Rice. eleven.

1 - a simple curlic pattern - a circle; 2 - simple curl pattern - oval; 3 - a simple curlic pattern - a spiral; 4 - loop-spiral; 5 - spiral loops; 6 - ball loops with a versatile arrangement of loop legs; 7-loop-balls with one-sided arrangement of the legs of the loops; 8 - snail loop; 9 - curved loop; 10 - incomplete curl pattern; 11, 12 - rarely seen scroll patterns.

Varieties of curl patterns are due to the peculiarities of their internal structure (Fig. 11): simple curl patterns - papillary lines of the internal flow form a pattern in the form of circles and ovals;

spiral - papillary lines of the internal flow form a pattern in the form of one or more spirals that make at least one full turn around their axis;

loop-spiral - papillary lines of the internal flow form a pattern in the form of a loop, curved spiral;

spiral loops - papillary lines of the internal flow form a pattern in the form of two independent loops that envelop each other, curved in a spiral;

tangle loops - papillary lines of the internal flow form a pattern in the form of two independent loops, one of which (called the envelope) goes around the head of the second (enveloped). The legs of the loops can be turned to one edge of the pattern - one-sided or to its opposite edges - versatile;

loop-cochlea - a pattern formed by two curved streams of papillary lines, starting from opposite edges, converging and enveloping each other in the middle of the pattern;

curved loop - papillary lines form a loop pattern, the loop head of which is lowered to its base and located between two deltas;

incomplete curl pattern - the papillary lines of the internal flow form a pattern in the form of incomplete circles (ovals) or spirals, which, with their convex side, face the delta (or deltas) of the patterns and in the upper part go around the loop or arcuate lines of the external flow. In incomplete scroll patterns, an incomplete circle (oval) must be at least a semicircle;

a rare whorl pattern - the papillary lines of the internal flow form a pattern that consists of a circle and a loop, a spiral and a loop, randomly located papillary lines of a complex shape.

The definition of the conditional center of the loop pattern, which largely determines the complexity of its internal structure, is important both for classification and for a comparative study by common features.

The conditional center of the loop pattern is considered to be a point at the top of the inner loop or one of the lines inside it and entering the head of the loop.

Rice. 12.

In cases where the inner loop is “clean”, the top of the loop will be the center of the pattern (Fig. 12). Direction and steepness of papillary line flows

Papillary patterns of loop and curl types are subdivided according to the relative direction of the papillary line flows:

a) in the direction of the legs of the loops:

ulnar - the legs of the loops are directed towards the little finger of the hand (little fingers);

radial - the legs of the loops are directed towards the thumb (large);

in the fingerprints of the right hand, loop patterns will be ulnar, the legs of the loops of which are directed to the right, and in the fingerprints of the left hand - to the left;

in the fingerprints of the right hand, loop patterns will be radial, the legs of the loops of which are directed to the left, and in the fingerprints of the left hand - to the right (This feature is used in practice when determining the hand and finger that left traces: the right loop patterns correspond to the right hand, and the left ones - left (with the exception of 30% for the index fingers);

b) in the direction of the papillary lines of the central flow of whorl patterns:

right-handed - twisting the lines into a spiral from the center of the pattern to its periphery clockwise by determining the hand that left the trace: right twist - right hand; left twist - left hand);

left-handed - twisting the lines into a spiral from the center of the pattern to its periphery counterclockwise.

There is the same exception for the direction of papillary lines in index finger prints with patterns of whorl types as for looped ones.

The rule applies to those types of curlicue patterns where the streams of lines in a spiral are clearly visible: a simple spiral; loop-spiral; spiral loops and snails.

Papillary patterns within their type and species may differ (except for the indicated signs) in the relative direction (slope) of the axes of the flows of papillary lines to the base of the pattern - the interphalangeal fold. This feature can be successfully used not only in the process of a comparative study of patterns similar in structure, but also as an independent feature in determining the hand and finger that left traces. To some extent, the slope also determines the steepness of the papillary line flows, which is also used in patterns of the same type and kind.

In fingerprint ten-finger accounting, when deriving an additional part of the formula, radial loop patterns are indicated by the number 2; ulnar - depending on the number of papillary lines from the delta to the center of the pattern - in numbers 3, 4, 5, 6.

The relative position of the parts (elements) of the papillary pattern. Number of papillary lines between them

In the papillary patterns of the loop and curl types, the sign of the relative position of the parts of the papillary pattern is independently investigated:

centers of loop patterns - in relation to the delta;

centers of curl patterns - in relation to the right and left deltas;

deltas of curl patterns relative to each other.

For the centers and deltas of loop patterns, their relative position is considered in two aspects:

firstly, the location of the delta of the pattern relative to the center along the vertical, determined by the height of the delta relative to the length of the loops of the internal flow (lower, middle, upper);

secondly, the distance from the center to the delta, expressed through the ridge count - the number of papillary lines between their central points (Fig. 13). This feature is used in 10-finger fingerprinting as classifying loop patterns when deriving an additional part of the formula with their digital designation:

number 3 - from 1 to 9 lines;

number 4 - from 10 to 13 lines;

number 5 - from 14 to 16 lines;

number 6 - 17 lines or more.

Rice. 13.

For centers and deltas of papillary patterns, only the option of counting lines from the right or left delta to the conditional center of the pattern is used, which in some cases (with a complex structure of the center) can be determined purely subjectively.

The sign of the relative position of the deltas in the patterns of the curlic type is classifying in the 10-finger fingerprint recording, which is based on the position of the left delta relative to the right one, determined by the number of papillary lines between their lower sleeves:

the internal position of the left delta - three or more lines above the right - is indicated by the number 7;

the middle position of the left delta - its lower sleeve is connected to the lower sleeve of the right delta or the number of lines between them is not more than two - the number 8;

the external position of the left delta - three or more lines below the right - the number 9.

When performing fingerprint examinations and conducting a comparative study, the relative position of parts and elements can be determined without regard to their exact quantitative expressions, general characteristics: higher-lower, right-left, less-more.

The internal structure of individual parts (elements) of the papillary pattern

Signs of the internal structure are considered as the complexity of the structure of the centers, deltas and nearby flows of papillary lines that make up the pattern.

For the centers of patterns, this may be due to the inclusion in their structure of the details of the structure of patterns in the form of short lines, fragments, dots, eyes, and for deltas - with a certain internal structure of the delta itself, its branches, with the presence or absence of features that simplify or enhance the visual perception of its structural complexity.

Some features of the structure of centers and deltas were described above (the structure of deltas, types and types of papillary patterns, the definition of a conditional center in loop patterns).