NCJ Number
131249
Journal
Journal of Forensic Sciences Volume: 36 Issue: 4 Dated: (July 1991) Pages: 1027-1043
Date Published
1991
Length
17 pages
Annotation
The feasibility of the use of infrared microscopy as a routine technique for fiber analysis was examined, and the utility of a computerized spectral library of fibers for the identification of generic class and subclass was evaluated.
Abstract
Infrared (IR) spectra were obtained of the fibers encountered in 72 fiber matches made during routine case work at the FBI laboratory. All fibers which were comparable by visual optical microscopy were also found to be comparable by IR microscopy. In addition, the chemical subclass was identified. The most frequently encountered generic classes of synthetic fiber were polyester, nylon, and acrylic. Several minor spectral differences were observed which arose from interference fringes, contaminants, and pressure effects due to sample preparation. A correct identification of these sources is important to prevent an erroneous attribution of the differences to chemical differences between the fibers tested. IR microscopy also allows easy analysis of bicomponent fibers and new fiber types not previously encountered in a forensic laboratory. The digitized spectral library can provide valuable assistance in the identification of both the generic class and chemical subclass of the fibers. In order to confirm an identification, visual examination of the first few selected reference spectra in the computer search with the unknown spectrum is required. 14 figures, 5 tables, and 19 references (Author abstract modified)