Clear packaging tape is pressed down on the surface of the clothes to lift off the hairs and fibers clinging to the surface, then placed on a sheet of clear acetate. All this clear stuff makes the fibers easy to see. In a perfect world. In reality, Barney and Phil will both be dressed in white cotton T-shirts and blue jeans, the two types of fibers so common as to have no evidentiary value whatsoever. There will be nothing your forensic scientist can do, no matter how much the cops plead.
White cotton is white cotton is white cotton.
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