Fibers are collected from a crime scene through careful and methodical procedures to preserve their evidentiary value. The common methods include:
- Using tweezers or forceps to pick up individual fibers that are visible and not firmly attached to surfaces. These are then placed in small containers like pill boxes, glass vials, or folded paper bindles to avoid loss during transport
- Using adhesive tape or adhesive lifts to collect fibers from larger surfaces or items where fibers may be loosely attached. The tape picks up fibers and can be stored for laboratory analysis. This method is especially useful for collecting fibers from bedding, clothing, or upholstery
- Vacuuming an area with a specialized vacuum device fitted with a filter to collect fibers from larger or hard-to-reach areas. However, some investigators prefer to avoid vacuuming at the scene to prevent collecting old or irrelevant fibers
Additional steps in fiber collection include:
- Documenting the exact location and number of fibers found, and photographing the evidence in place with scales for reference
- Wearing clean gloves to avoid contamination and changing gloves between collections to prevent cross-contamination
- Collecting entire items (like clothing or carpet samples) when possible, so fibers can be extracted later in the lab for comparison
- Packaging collected fibers and items carefully in paper bags, pill boxes, or cardboard boxes to prevent fiber loss during transport
Once collected, fibers are analyzed in a forensic laboratory using techniques such as polarized light microscopy, UV-Vis microspectrophotometry, and Fourier transform infrared spectroscopy to determine fiber type, color, dye composition, and chemical makeup, which can help link suspects to crime scenes
. In summary, fibers are collected using tweezers, adhesive tape, or vacuum devices, with meticulous documentation and packaging to preserve trace evidence for laboratory analysis.
