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Application of Fluorescence Line Narrowing Spectroscopy to Forensic Fiber Examination

NCJ Number
Date Published
April 2011
144 pages
This project's objective was to develop a nondestructive analytical methodology capable of producing highly discriminating identification of textile fibers collected as physical evidence in criminal investigations.
The method developed focuses on the total fluorescence emission of fibers. In addition to the contribution of the textile dye (or dyes) to the fluorescence spectrum of the fiber, this research examined the contribution of intrinsic fluorescence impurities - i.e., impurities embedded in the fiber during fabrication of garments. This is a reproducible source of fiber comparison. This method of comparing and matching fibers eliminates the need for destructive dye extraction while significantly increasing the discriminating power of fluorescence microscopy. This method of comparing fibers is important because it does not require the destruction of the evidence in the course of extracting the dye from both the known and questioned fiber for further chemical analysis. In addition to destroying the fiber evidence, the comparison of extracted dyes is difficult because of the large amounts of textiles produced each year in replicate fiber types and colors. Further, it may not be possible to discriminate between two fibers that have been dyed with highly similar dyes. The spectral features of the visually indistinguishable fibers studied in the project provide remarkably different RTF-EEMs (room-temperature fluorescence spectroscopy and excitation emission matrices). Although a larger pool of visually indistinguishable fibers should be examined in the future, the current project achieved the goal of presenting proof of concept that provides a foundation for the development of a nondestructive methodology for forensic fiber analysis. The new methodology should be tested across multiple types of data often encountered in forensic science, so that the practical implications of the results are understandable and the methodology easily explained to juries. Extensive figures, 84 references, information on the dissemination of research findings, and appended supplementary information

Date Published: April 1, 2011