Trasology is the field of forensic science engaged in the study of traces, objects that leave them, and mechanisms of trace formation. In this area, the means, methods and techniques of detecting, fixing, preserving, seizing, examining fingerprints to establish the circumstances of the commission of a criminal act are also investigated. These circumstances are identified and recorded for further criminal proceedings. In trasology, the classification of traces is diverse, and the use of each of them contributes to the rapid disclosure of crimes.
Trasology system
The study system includes the following aspects:
- General questions, including consideration of trail classifications in trasology.
- The study of prints of various types (from legs, arms, teeth, vehicles, weapons of crime).
- The study of objects that are traces of illegal actions (establishing their condition, collecting the whole of the parts, determining the source of the occurrence of objects by conducting a study of the mechanisms of their production).
- Investigation of various substances - traces of criminal offenses.
Definition and classification of traces in trasology
A trace is a material display of the signs of the structure of real objects on other objects with which these objects interacted. Impressions in trasology allow us to determine the set of facts important for the investigation of a case. The following circumstances are established for them:
- impact mechanisms (e.g., angle or strength of interaction);
- the key circumstances of the crime (the method of mutilation or penetration into the premises);
- group affiliation (type of car on tire prints);
- the identity of the subject (the fact of leaving fingerprints of one person in different places of crime).
There are three large groups of traces in trasology:
- Mappings - indicators of signs of the object that left them, and the mechanism of formation (signs of hacking, fingerprints, residual blood).
- Items - the remains of objects that were used to commit illegal actions (lock, torn seal, broken glass).
- Substances - secondary indicators for establishing the mechanisms of impression formation, their grouping and identifying other signs (dust deposits, car paint particles).
Classification Types
Classification of traces in trasology is carried out for various reasons:
- by source of occurrence;
- by the mechanism of appearance, the strength of interaction with the object;
- according to the level of perception;
- by the features of the impact provided by the objects of trace formation;
- at the locations of deformations on trace objects.
Each of the presented groups is divided into different types. The study of prints from different positions allows you to effectively solve crimes.
According to the source of occurrence, four types of tracks are distinguished:
- human
- impressions of tires and paints of vehicles;
- animals;
- prints of tools, implements, industrial-type mechanisms.
According to the mechanism of appearance and the strength of interaction with the object, two types of prints are distinguished:
Imprints of a surface type are left by subjects who act on an object with a force that is not able to cause a complete deformation of the trace-perceiving object. They cause changes exclusively on the surface.
Volumetric impressions arise due to the deformation of the object, on which the criminal acted with special force. A feature of such traces is specularity, display in three-dimensional format of the affected object.
According to the level of perception, three types of prints are distinguished:
- Visible - detectable without the use of special tools, techniques, distinguishable to the naked eye.
- Weakly visible - the presence of which is established by using special devices because of their small size or color masking.
- Invisible - detected only with the use of special tools, tricks due to their small size, as well as the presence of other concealing circumstances.
Classification of traces in trasology according to trace-forming objects, their impact on objects establishes two types of prints:
Fingerprints of a statistical type (prints) appear if, during the contact of a track-forming object with a track-sensing object, friction of one object on the outer surface of another is present.
Traces of a dynamic type occur during the sliding movement of two objects interacting with each other (or one of them). As a result of their mutual influence, two forces in different directions leave prints on the contact surface in the form of rollers or furrows.
Types of prints at the location of the changes that occurred on the track-perceiving objects:
Peripheral traces appear as a result of changes in the zone located outside the territory of interaction of the two objects. Fingerprints of a local type arise due to changes that occur within the boundaries of contact between the trace-accepting and trace-forming objects. At the same time, the surface has not changed around this track.
Hand marks
One of the classifications of material traces in trasology is the grouping by human fingerprints. One of the types of prints is handprints. This type of fingerprint most often contributes to the successful disclosure and investigation of the crime. The increased detection of criminal offenses is due to the fact that they carry out the main function when performing actions, having at the same time potogiruyu substances that allow you to quickly identify the owner.
On the palms (or soles of the feet) there are papillary lines - linear elevations of small width and height, which are separated by small furrows. In areas of small size, the lines of the papillary type are straight, and in the longer sections they are curved, as a result of which they form different patterns. These lines on the arms do not intersect. They can merge, disconnect, creating complex patterns as a result.
In addition to papillary lines, in contact with the surface of the hands, other types of prints are left: flexion (flexor) lines, wrinkles, wrinkles, scars, pores, burns, etc.
Of great importance in the classification of traces of mappings in trasology is the relief, which is created by lines of the papillary type. Basically, these are patterns located on the pads of the upper phalanges of the fingers on the hands. They are studied by a special section of trasology - fingerprinting. At the same time, not only fingerprints are examined, but also their properties: stability, individuality, and recoverability.
Footprints
The classification of material traces in trasology as a separate group distinguishes footprints. By frequency of detection, they are in second place after fingerprints. Detection of footprints with their subsequent investigation allows you to establish key circumstances that are important for the successful search for the offender, bringing him to justice.
These prints allow you to learn a lot of information about a person:
- height;
- gait features (e.g. lameness);
- signs of criminal footwear;
- circumstances of the act (pace, direction of movement).
Together, these facts make it possible to identify the offender to restore the picture of what happened.
There are different types of tracks:
- foot prints;
- traces of the sole of the shoe;
- prints of bare feet in socks.
In trasology, the classification of footprints by probability of detection distinguishes two types of prints:
- superficial (which is clearly visible only if the shoes are stained or painted);
- voluminous (which are easily detected at the crime scene).
When examining footprints without shoes, the following symptoms are determined:
- foot length;
- width, finger length;
- sole shape;
- the structure of common papillary patterns;
- the presence of flexion (flexor) folds.
When examining footprints in socks, three signs are determined:
- stocking size (sock);
- scheme, type of interweaving of material threads;
- factory-style seams on toes and heels.
Teeth imprints
In trasology, types of tooth marks can remain on products, other objects, the human body. These prints make it possible to establish the circumstances of their formation and identify the person. Dental examination is carried out by a dentist and forensic specialist.
According to the features of the process of formation of prints, the traces of a bite and a bite are distinguished. If we are talking about bite prints, investigators can determine the shape and size of the dental arch, the presence of asymmetry of the left and right, the inclination of the teeth, their number, the presence of prostheses, the distance between the dental units.
Prints of nails
In trasology, the concept and classification of nail traces is often associated with the body of a criminal or victim. According to human nails, seven signs are determined:
- The form.
- Relief.
- Contour of the nail plate.
- The value of the free edge.
- The length and width of the plate.
- The color of the nail.
- Features
The fact of self-defense, the methods of mutilation, the fact of strangulation, etc., are established by the location and presence of fingerprints. Nail prints are photographed and recorded in the protocol. If there is a suspicion that the suspect has particles of the victim’s skin or other foreign substances under the nails, the nails are cleaned, trimmed, and all this is sent to a forensic examination.
Traces of clothing
In trasology, the concept and classification of traces of clothing is rather narrow. Particles of clothing can be found on the surface of the vehicle (when hitting a pedestrian), on the ground (during the fight between the victim and the offender), at other objects.
Traces left by clothing are photographed by shooting to scale, recorded in the protocol. If particles of things are located on the surface of the machine, they are copied onto a fingerprint film. Plaster casts are made from volume prints.
Traces of blood
In trasology, the concept and types of material traces of blood are defined as fingerprints-substances. Examination of the form of the traces left at the crime scene or the clothes of the suspect helps to establish how they arose.
According to the results of the study, you can determine the conditions for the appearance of blood, get a picture of the individual moments of the crime.
Residues are divided into five types:
- spray;
- puddle;
- drops;
- blots;
- blood loss.
A full study of the prints left allows you to restore the course of action, which as a result makes it possible to solve the crime and bring the guilty person to justice.
Based on the results of the audit, the following facts are established:
- Location of the crime.
- Possible nature of damage.
- Options for moving the body of the victim.
- Whether self-defense or struggle was present.
- Could some of the blood remain on the suspect’s body and clothes.
- What was the victim’s posture when injured.
Forensic scientists take pictures of all the places where at least a drop of blood has been detected. If the remains are dried, they are redrawn through transparent paper, with the contours circled. A study of the fingerprints is carried out at the crime scene and in the laboratory (based on the photo).
Mechanoscopy
The general provisions of trasology on the classification of traces left by instruments of crime and other objects used as weapons are studied by a special section of trasology - mechanoscopy.
Forensics determines that the mechanisms and instruments of crime are devices whose fingerprints and actions are not directly related to the strength of human hands, but depend on the design and functioning of the details of the subject and the level of intelligence of the subject.
Fingerprints of a mechanical type are indirectly related to the physical characteristics of a person. They indicate only the presence of the subject of specific skills, knowledge, skills. With the help of investigative measures and actions, a causal relationship is established with the subject and object of the crime.
In the process of diagnosing mechanisms, tools and implements on the left prints, signs of the size, shape and location of the prints are taken into account. When conducting identification studies, the sizes, configuration, and location of the features that make up the micro- and macrostructure of the surface are checked.
According to common signs, imprints of tools and items used in the process of committing a crime are divided into four types:
- voluminous;
- superficial;
- dynamic;
- static.
In trasology, the types of traces of crime instruments are divided for various reasons:
- by types of items;
- by methods of exposure;
- by the nature of the impact.
By types of objects, four types of impressions are distinguished in trasology:
- Cutting (scissors, knives, etc.).
- Mortising and cutting (chisel, ax, crowbar, etc.).
- Drilling (drills, drills, etc.).
- Sawing (saw, file, etc.).
Types of tools and implements by methods of exposure:
- thermal (electric and gas devices intended for cutting and welding of metals);
- mechanical (glass cutters, scissors, knives, chisel, ax, saw, crowbar, drills, drills).
By the nature of the impact, three types of traces are distinguished:
- Spin (pressure) - formed from pressure or impact by a hacking tool on the outer surface of the obstacle.
- Friction (slip) - occurs when the gun acts on the surface of the obstacle at an angle.
- Sawing, cutting, drilling - arise in the process of the corresponding impact on the barrier.
Trasology allows for the remnants of the skin, blood, other substances and objects left by the criminal and victims to get a complete picture of the crime and establish the identity of the guilty person.