Trasology: when Sherlock follows the trail

[Brother]

If the title of the article mentions the shrewd detective Sherlock Holmes, then we will talk about the investigation of crimes. Elementary! In this article we will talk about why modern Sherlocks solve criminal cases - about traces. And that a whole discipline is devoted to their study - traceology. We wish everyone who is ready to replenish their knowledge base a fascinating reading. However, before that, it will be good if you check your knowledge in this area before reading the article.

Definition of traceology​

Trasology is a section of forensic science that deals with the analysis of traces found at a crime scene. Tiny pieces of physical evidence, such as hair, fibers from clothing or carpets, pieces of glass, paint, etc., help investigators to put together a picture of what happened. They are called footprints and are formed when two objects come into contact with each other.

The main principle of traceology is as follows: it does not matter what actions the offender committed, but at the crime scene he will definitely leave traces, and also take some of the traces with him. The offender can leave fingerprints or footprints, skin particles, blood, or other bodily fluids. In turn, the objects with which the attacker came into contact will also leave traces on him. For example, dirt from the crime scene can get stuck in the sole of his boots, and hair from the victim's head can remain on the sweater.

Types of footprints​

There are situations when traces become the only source of information for the investigation, therefore, forensic experts at the scene are purposefully looking for and carefully collecting everything that can give clues and identify suspects. The following traces may be left at the crime scene:

Hair​

Hair is the most common type of marks. They fall out easily (the average person loses about 100 hairs a day) and are easy to spot. Examination can show whether individual hairs belonged to a person or an animal. If it turns out that the hair is human, then further analysis is able to determine the race and the area of the body on which it grew. If a hair follicle (root) is attached to the hair, it is sent for DNA testing to try to establish the identity of the owner.

Fiber​

Fibers are filamentary elements of fabric and other materials. They are divided into 2 categories: natural (animal or plant fibers such as wool, cotton or silk) and synthetic (completely artificial). For example, carpet fibers found on a suspect's shoes may indicate their presence at a crime scene.

Glass​

In forensic science, glass is used both to collect evidence, such as fingerprints or blood stains, and as an independent trace for further analysis. Fragments of glass from a crime scene can be valuable evidence of a person's involvement in a crime, because small fragments easily get stuck in the soles of shoes, in hair or on clothes.

Dye​

The study of paint traces is especially relevant when it comes to crimes related to transport and burglary. Particles of vehicle paint (vehicle), deposited on the clothing of the injured pedestrian, may become the only evidence in the investigation of the accident. Paint analysis allows you to determine the brand, model, and sometimes the year of the vehicle.

In the event of a break-in, when tools were used to enter the room, the paint from them may remain on the opened door, or vice versa, particles of the painted surface on the tool.

Shot marks​

The analysis of the shot marks shows whether a firearm was used at the crime scene and, if so, how far the shooter was from the object / person. In some cases, it is also possible to determine the type of weapon.

Prints​

Fingerprints are formed when two objects come into contact with sufficient force. They are either two-dimensional, such as fingerprints, or three-dimensional, such as bullet marks.

Tire and shoe prints are often present at the crime scene. After conducting the analysis, the investigator receives information that helps in the search for suspects: the type of shoe and the approximate size, the number of people at the crime scene, the type and model of the vehicle.

Other​

This category covers other types of physical evidence and may include traces of: biomaterial (remains, saliva, blood, skin particles), chemicals, soil, debris left after a fire, etc.

The search for traces is carried out both at the crime scene and on the clothes of the victim, suspect, or in the place where they could have been before the moment of the incident.

How traces are collected and analyzed​

When examining a crime scene, the investigator determines which traces need to be collected and sent to the laboratory, in which order they should be processed. The priority of the analysis is assessed based on the level of identification that a given piece of evidence can provide.

In the process of collecting traces, a variety of tools are used: tweezers, film (electrostatic for removing dust, adhesive, protective), special paper (for example, for taking tire prints), vacuum cleaners, brushes, sterile swabs, alternative light sources, lasers, etc. The collected samples are packaged, documented and sent to the laboratory.

When analyzing traces, different methods are used:

1. Microscopy and spectroscopy. In this way, the color and shape of the cross-section of the fibers is determined; look, texture and visual aspects of hair; optical properties of glass; thickness and structure of paint layers.
2. Chemical tests. They show the presence of nitrites, copper and lead when analyzing the traces of the shot; toxins, drugs and dyes when examining hair; and also help determine the composition of fibers and dyes.
3. DNA research. This method is used to analyze biomaterial: hair follicles, saliva, blood, skin particles, fingerprints, etc.
4. Magnetic resonance imaging and computed tomography. Most often it is used to identify the remains of the body, for example, in a fire, and allows you to determine the sex, age and individual characteristics of a person.
5. Mathematical methods. With their help, you can analyze shoe prints and calculate the walking line, the length and width of the stride, the angle of the foot turn.

After identifying the key characteristics of the footprints, analysts turn to special databases that contain samples of various materials, and try to find a correspondence between the footprints from the crime scene and the samples. There are bases of fingerprints, firearms, bullets, glass, fibers, etc.

For example, the United States has the National Automotive Paint Archives, an FBI database that contains over 45,000 samples of automotive paint produced since the 1930s. With its help, you can determine the year, make and model of the car.

Trasology in action​

Could powder be the main piece of evidence in a murder case? Is it possible to catch a maniac thanks to dog hair or carpet fluff? The answer is yes. The importance of footprints in the context of an investigation should not be underestimated. The examples below are proof of this:

• In 1912, the murder of a young girl Marie Latelle at her parents' house shocked the whole of France. It happened at midnight, and no signs of a break-in were found, which gave the police reason to suspect the girl's lover, Emil Gurbin, of the crime. But he had an iron alibi: during the murder, Gurbin played cards with friends, who unanimously confirmed this fact. Since the victim was strangled to death, the police decided to scrap the suspect's nails, and found something that looked like skin particles in the sample. At that time, forensic science was in its infancy, so biological tests were out of the question. On closer examination under a microscope, the investigator noticed that the skin particles were coated with a pink powder, which was found to contain magnesium stearate, zinc oxide, bismuth and red iron oxide, ingredients used in cosmetics. It was the face powder used by Marie Latelle. Gurben was exposed, and he pleaded guilty, saying that he deliberately moved the clock in the card room to provide himself an alibi.
• Serial killer and necrophiliac Ted Bundy, who operated in the United States in the 1970s, was convicted in part because of evidence that bite marks found on the body of one of the victims were from his teeth.
• Another maniac, Wayne Williams, was sentenced to two life sentences in the infamous 1982 Atlanta murder of children, thanks to the fibers from Williams' home carpet found on the bodies of the victims.
• A dog is a friend of man, but its fur can become an enemy for a criminal. It was wool that became one of the key pieces of evidence in the case of the murder of seven-year-old Daniel van Dam in 2002 in the United States. The girl disappeared without a trace from her bedroom at night. Suspicion fell on the neighbor. When police officers searched his trailer, they found dog hair, although the suspect did not keep pets. The forensic lab determined that it was the fur of the Van Dam family dog that was caught in the killer's trailer from Danielle's pajamas.

These stories prove the importance of traceology as one of the forensic methods to expose a criminal.

Trasology to help an ordinary person​

Transport and traceological examination (TTE) is the case when traceability can be useful in life for an ordinary person. It is carried out in case of road traffic accidents (RTA) or other damage to the vehicle and helps:

• restore the picture of events;
• establish the brand and model of the vehicle involved in the accident;
• identify the culprit of the accident;
• find out how the damage was caused (by an object, another vehicle or an animal).

TTE will be useful if a dispute arises between the participants of the accident, with the insurance company or, for example, with a neighbor who is sure that you scratched his car when leaving the parking lot. In these cases, you can safely contact an expert traceologist who will fix the traces, collect the necessary samples for analysis and make an opinion.

Footprints tell a story. For this reason, some criminologists call them "silent witnesses." Both the literary hero Sherlock Holmes and the real police officers are directly related to traceology and demonstrate the importance of this discipline: they find traces, analyze them and draw reasonable conclusions about what actually happened at the crime scene.

And we just can't help but mention that we have a special course "Profiling". If you want to learn how to “read” people and their true emotions, understand the motives of their actions and deeds, recognize lies and deceit, we highly recommend that you go through it. Who knows, maybe the knowledge that you will receive will one day save your life or allow you to avoid a serious danger, so that the matter simply does not come to the same traceology.

Friends, we wish you to be attentive, discerning and comply with the laws of the state and conscience. Good luck!