AVALIAÇÃO FORENSE DE FIBRAS VIA MICRO ESPECTROSCOPIA (FTIR-ATR)

Abstract

Forensic assessments may involve sampling textile fibers when examining crime scenes. The need to characterize and identify these fibers is of great importance, as they can provide comprehensive information about a crime, linking a suspect to a location, based on characteristics such as length, diameter and, particularly, the composition of the fibers. Fourier transform infrared micro spectroscopy in attenuated total reflectance mode (micro FTIR-ATR) is considered a non-destructive, fast and practical method for fiber identification. In this study we performed a forensic evaluation of sixty textile fibers recovered from twenty fabrics, all with white color, via micro FTIR-ATR analysis. Fiber collection was based on the tape lifting method, in order to simulate a collection in a real crime scene. The data were plotted in a two-dimensional analysis of principal components and in a radar chart to favor the comparison of the composition of the materials. The results of the infrared spectra revealed that the technique allows the discrimination of textile fibers according to their spectral composition (cellulose, ester, polyester or a mixture of these compounds) and some characteristics, such as number and width of peaks, position of the peak according to the wave number, absorbance index related to peak sharpness. It was concluded that the technique was useful and practical in the forensic evaluation of the fibers, presenting quick and enlightening results.