Trace evidence
Importance of Trace Evidence in Forensics

Importance of Trace Evidence in Forensics

Trace evidence is the microscopic material found on the crime scene which has great significance in solving criminal cases. These are very small in nature and can’t be seen by the naked eye sometimes and can be transferred from one place to another very easily.

Each and every contact leaves behind a trace and hence a person can be linked/unlinked to being present at a particular place.

Trace evidence is also known as “silent witness”. Trace evidence links a culprit to the crime scene, or things involved. Trace evidence is found in many forms from as large as a brick to as small as a hair strand. It can be used to investigate every type of crime from rape to terrorist attacks.

Trace evidence characterizes a particular environment there will be an infinitesimal correlation between the evidence of different environments. Typically trace evidence includes hair, fibers, bloodstains, paint, glass pieces, gunshot residues, body fluids, etc.

Types of Trace Evidence

Depending on the nature of the crime, different amount of traces is found at the crime scene that correlates to victim, perpetrator, and environment. The environment in this case means either the natural or the precise location of the crime.

In a crime scene, different types of evidence are found however the common examples are:

  • Hair
  • Paint
  • Glass
  • Fibers
  • Soil
  • Fire debris
  • Body fluids
  • Chemical residues

1. Hair

Hair is a characteristic feature of all mammals including humans. It is an integral part of the skin derived from the epidermis of the skin. Human hair can be connected with a specific racial group grounded on recognized prototypes for every group. Forensic experts distinguish between the hair of animals and humans.

Forensic scientists distinguish six types of hair on the human body i.e.,

  • Head hair
  • Eyebrows and eyelashes
  • Beard and mustache hair
  • Underarm hair
  • Auxiliary or body hair Pubic hair.

Hair also helps in differentiating between sex of humans. Male hairs are Coarser, darker, and thicker while female hair is long, fine, and silky. Hair also includes Human DNA that helps in concluding if a particular strand belongs to a suspect or not.

2. Paint

Paint is found at a crime scene and is generally transferred from one place to another through the suspect. Paint chips are generally found in hit-and-run and burglary cases. It is used to compare the vehicle involved in the incident.

Paint chips from burglary tools can be used to determine whether the tool is used in a crime or not. In assault cases, paint can be used if it is left at the crime scene and the weapon consisting of paint could be found at the suspect’s home.

3. Glass

Glass plays an important role as trace evidence in cases of arson, hit and run, burglary, and theft. Glass that has been broken or fragmented at a crime scene is crucial forensic evidence found.

In theft cases, broken window pieces are found, and glass fractures are seen in gunshot cases. Through this, we can identify the direction of the bullet shot. The density method is used to compare the glass to observe the origin of the glass.

4. Soil

Soil can provide important information during criminal investigations as transfer evidence because many criminal cases take place under circumstances such that soil transfers to a criminal or victim. The variation in soil from place to place makes the soil a valuable piece of evidence to prove the linkage between a suspect and a crime scene. The texture of soil varies from place to place.

5. Fire Debris

The basic role of an investigator at a fire scene is twofold: firstly to determine the origin of the fire (the site where the fire began), and secondly to examine closely the site of origin to try and determine what it was that caused the ignition at or around that location.

An examination would typically begin by trying to gain an overall impression of the site and the fire damage; this could be done at ground level or from an elevated position. From this, one might proceed to an examination of the materials present, the fuel load, and the state of the debris at various places.

6. Body Fluids  

Body fluid traces recovered at crime scenes are among the most important types of evidence to forensic investigators. They contain valuable DNA evidence which can identify a suspect or victim as well as exonerate an innocent individual.

The first step of identifying a particular body fluid is highly important since the nature of the fluid is itself very informative to the investigation, and the destructive nature of a screening test must be considered when only a small amount of material is available.

Importance of Trace Evidence

  • Since they are smaller in size and almost invisible to the naked eye they remain hidden from the culprit to later help in the investigation.
  • Provides a vital link between the crime, suspect, and the victim.
  • Helps in confirming the theory of the investigators.
  • Helps in matching the original origin of the evidence with accuracy for clear ideas during an investigation.
  • Also helps in reconstructing the crime scene.
  • May provide clear information about the suspect(s).

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