Physical evidence is crucial in proving a crime and linking suspects and victims to a crime scene. Physical evidence can be brought into the courtroom and examined, significantly impacting the verdict. Depending on the nature and setting of the criminal occurrence, physical evidence might take almost any shape or size, and it could be present at the crime scene, moved between the victim and the assailant, or in any other area based on the activity of those involved.
The physical evidence is defined as any tangible item that has some connection or information pertaining to a trial. Also known as real evidence, they can be held and touched and is often found at the crime scene.
Here we have listed some of the most typical types of physical evidence found in forensic or crime labs.
- Body fluids: This type of evidence is primarily blood, sperm, or saliva, which can be found on clothing or other fabrics or objects in liquid or dried form. These components are commonly gathered from a crime scene or a person on sterile fabric patches or swabs for species identification and possible individualization using serological methods or DNA analysis. Other body excretions, such as urine, sweat, and feces, may be identified in various stains or materials.
- Body Tissues: This includes autopsy samples of various organs, as well as blood, urine, and stomach contents, that are collected for toxicological analysis.
- Drugs and Controlled Substances: This category includes plant materials, powders, tablets, capsules, or other preparations for identification and weight.
- Fibers: This category includes fibers for identification and comparison, either natural (cotton, wool) or synthetic (rayon, dacron).
- Fingerprints, Palm Prints, and Foot Prints: This category includes visible or latent prints lifted or cast from various surfaces for comparison and identification. This category frequently includes tire and footwear impressions.
- Fire and Explosive Materials: This includes liquids, solids, or burned debris to identify accelerants and explosive residues.
- Firearms and Projectiles: This includes identification, source, and comparison of projectiles, as well as firearm test firings, distance determinations, and firearm operability.
- The glass includes traces or big chunks of glass. Glass fragments may be linked to a suspect and a break-in, or glass fractures may be analyzed to determine the direction of the force exerted or the sequence of rounds fired. Glass analysis is frequently used to reconstruct automobile accidents.
- Hair: This includes hair collected from a crime scene, a victim, or a suspect to determine the species (animal or human), race, and the origin of the body part. Hair morphological traits can be used to include or exclude a suspect if they are human. It’s also possible to tell if the hair was crushed, clipped, burned, forcibly removed, or fell out.
- Oils and Grease or Cosmetic Products: This includes oils and grease, as well as cosmetic items, that are transported between objects and people and have distinct compositions that may be compared.
- Paint and Paint Products: This includes paint that may have transferred from one object to another on numerous surfaces, such as in a vehicle collision. This form of paint fragment transfer is commonly examined on the clothing of pedestrians struck by a car.
- Serial Numbers: This includes unique identifiers that are frequently altered or removed from vehicles, firearms, and other objects. Serial numbers can be restored for appropriate identification using chemical etching.
- Soils and Minerals, Wood, and Other Vegetation: This includes soils and minerals, as well as wood and other forms of plants, which are identified and compared to find a credible source or location that can be linked to a suspect or victim.
- Tool Marks: This includes surface impressions or scratches that may reveal the type of object that created them. Wear features on the object or instrument, such as a prybar or screwdriver, provide distinct characteristics for comparison with the impression. Clothing or fabric impressions on vehicle parts have been linked to pedestrian hit-and-run accidents.
- Questioned Documents: This includes a type of physical evidence that can consist of handwritten, typed, copied, or computer-generated documents that are inspected for forgery evidence. To determine authenticity, the studies may include ink and paper analyses as well as handwriting comparisons. In the case of erased, physically damaged, or burnt papers or materials, restorative processes may be used.
Physical evidence is vital in criminal investigations. It can provide crucial links between suspects, victims, and the crime scene. Forensic or crime labs have advanced technologies and techniques to analyze and identify physical evidence. However, the admissibility of physical evidence in court depends on numerous factors, including chain of custody, authenticity, relevance, and reliability. Therefore, handling physical evidence carefully and preserving it properly is essential to ensure its admissibility in court.
