FIBERS - PART ONE: THE NATURAL LOOK

One could attempt to extract the dye used to color the fabric, and perform thin layer chromatography; this is considered difficult at best and impossible at worst, and would probably only be done by labs with a lot of time on their hands.

Fibers will be examined in cases where there has been physical contact—rape, assault, stabbing, cases where the body was thrown in a trunk, or the murder occurred at the suspect’s place and the victim dumped somewhere else. If you’ve got a drive-by shooting—forget fibers.

So let’s take a case where Barney beat the crap out of Phil. We have both Barney’s and Phil’s clothes. (The clothes they were wearing at the time of the crime, not the clothes they were wearing when they were arrested, which may not be the same thing. A CSI would be sure to pin their cops down on this before they did a lot of pointless work.) First you take Barney’s clothes to one room, and Phil’s clothes to another. On a clean table, or preferably a clean sheet of paper, the clothes are spread out and ‘taped’. (Ever ‘tape’ lint off your clothes? Same thing.) 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. I would even cheat and put the sheet of acetate right on the microscope stage instead of removing each fiber and mounting it on a glass slide—not proper, but a quick screening method. Now, in a perfect world, Barney would be wearing turquoise nylon and Phil would be clad in magenta polyester—nice, bright fibers that are easy to find and identify. 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.

On the other hand, if Barney is wearing a thick cotton/wool poncho in earth tones, and Phil’s shirt is covered with fibers of brown, tan, yellow and white cotton and white and tan wool…then Barney’s got some ‘splaining to do.

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