a very unusual cross-section. they were also very brittle. they were brittle because of degradation due to age and exposure. the fibers were triangular in shape, or trilobal. using an infrared spectrometer, palenik discovered the fibers were polypropylene, a synthetic fiber used for carpeting. he then analyzed the fibers gathered from smithart s truck and clothing. we find in smithart s environment exactly the same kind of fibers. not only the same cross-sectional shape, but the same pigments used to color them. everything is there. the fibers in smithart s truck were manufactured by the same company and had the same degree of environmental damage as those found on mandy s clothing. finally, palenik examined the most unusual evidence, the