Fibers are collected using various methods, primarily depending on the location and nature of the material being collected. Here's a breakdown of how it's typically done:
Methods of Fiber Collection
Fibers are commonly gathered from crime scenes, or other locations of interest, using the following techniques:
-
Tweezers:
- Used for picking up individual, visible fibers.
- Ideal for collecting larger or more robust fibers.
- Allows for precise and careful handling to prevent damage.
-
Tape:
- A sticky tape is pressed onto the surface containing fibers, capturing them.
- Effective for collecting small, numerous, or difficult-to-see fibers.
- The tape is then carefully placed on a clean backing for preservation and analysis.
-
Vacuum:
- Specialized forensic vacuum cleaners are used to collect fibers from larger areas.
- Often used on carpets, upholstery, and clothing.
- The vacuum cleaner has a filter that captures fibers, preventing loss.
Practical Steps
Once collected, fibers are carefully handled to prevent contamination:
- Secure Packaging: Collected fibers, whether on tape or as individual samples, are placed into a clean, sealed container or bag.
- Labeling: Each collection is labeled with relevant information, such as the date, time, and location.
- Chain of Custody: Following the chain of custody ensures the integrity of the evidence.
Laboratory Analysis
After the fibers have been collected, they are sent to a lab for thorough analysis. Here, various tests are performed to help identify the fiber, including:
- Microscopic Examination: Visual analysis of fiber shape, size, color, and structure.
- Spectroscopy: Using light to analyze the molecular composition of the fiber.
- Chemical Tests: Analyzing the fiber's reaction to different chemicals.
These tests help determine the type of fiber (e.g., cotton, polyester, wool), its source, and its possible association with a person, place, or object of interest.
| Method | Description | Best Use |
|---|---|---|
| Tweezers | Picking up individual, visible fibers | Large or robust fibers |
| Tape | Pressing sticky tape to capture fibers | Small, numerous or hard to see fibers |
| Vacuum | Using forensic vacuums to collect from large areas | Carpets, upholstery and clothing |
By using a combination of these methods and a rigorous lab analysis process, experts can accurately identify and use fiber evidence effectively.
