Read Online Behind the Yellow Tape: On the Road With Some of America's Hardest Working Crime Scene Investigators by Jarrett Hallcox, Amy Welch - Free Book Online Page B
Authors: Jarrett Hallcox, Amy Welch
Tags: General, True Crime
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it’s been done.” That’s very true. Forensic science is much like law or medicine—it is a practicing art. Not only does the science change each year, but the environment CSIs deal with differs with every call. Each situation they face presents new and unique challenges. “How do you string a bloodstain in a trailer hallway, with that really nasty and greasy shag carpet that nothing will stick to?” Detective Carnahan said, referencing a recent case. “You simply must improvise.” And they do—in that case, by fashioning fishhooks from safety pins (which Detective Carnahan’s wife provided by running to the store) and hooking one end into the carpet and the other end to the colored string. In Boone County, working crime scenes can truly be a team effort.
This synergy and broad view of crime scene investigation is really what nailed John Snow to the murder of Patricia Volpenhein. Despite his paranoia, the evidence he left at the scene was limited: the two tarps, a glove, and tread wear from the truck. The glove and tread wear are typical of the kinds of evidence that can be photographed, cast, or collected. But the tarps, two eight-by-ten blue plastic tarps, presented a unique challenge. “Before the academy, I wouldn’t have processed the tarps,” Detective Carnahan told us as we got back into the vehicle to head back to the sheriff’s department. But now, he said, “Instead of looking at things as if we could not process them, we now look at everything as something that can be processed; that broad perspective is what your training provided to us.”
Television has provided viewers, and therefore potential jurors, with the unrealistic expectation that all CSIs are like the ones found in prime time. Unfortunately, that could not be any further from the truth. We have held classes on developing latent fingerprints in which thirty-year veterans in the field had no idea that a fingerprint could be lifted off anything other than something smooth, like a piece of glass. Imagine working crime scenes for thirty years without having the background to know how to develop prints off all types of surfaces? How many more crimes could have been solved?
Looking for a fingerprint on two eight-by-ten tarps (front and back) is like looking for a needle in a haystack. But the only way to find that needle is to look, and look is what Detective Carnahan did. He decided that in order to process the tarps, he needed to superglue-fume them. Common, everyday superglue, dabbed into a small pan and heated, causes the glue to give off gaseous vapors that stick to the ridges of an oily fingerprint and make it more readily visible. On larger items, a fan is sometimes used to help circulate the vapors throughout the container. In order to superglue-fume something, however, the item must be completely contained so that the entire surface area is exposed. Carnahan studied the situation and jotted down a schematic for a large frame that he wanted the maintenance guys at the sheriff’s department to create. The frame would allow the tarp to hang completely inside the container with both sides exposed. The real ingenuity came when, instead of building solid walls, he decided to contain the fumes with plastic wrap—industrial plastic wrap, like the kind used to wrap pallets for shipment on trucks. In essence, Carnahan made a large box using the plastic wrap for the sides. This made it easy to put the tarp and the superglue in the container, along with a fan to help circulate the fumes. It also allowed him to put a test print, his own, on the inside of the plastic to know that the process was working. With his superglue-fuming contraption in place, he simply wrapped the frame tightly and let the tarp fume. This procedure was performed twice, once on each tarp.
“I then simply cut the plastic and removed the tarp,” Detective Carnahan told us as we all walked down the corridor in the sheriff’s department to where all of the evidence is
This synergy and broad view of crime scene investigation is really what nailed John Snow to the murder of Patricia Volpenhein. Despite his paranoia, the evidence he left at the scene was limited: the two tarps, a glove, and tread wear from the truck. The glove and tread wear are typical of the kinds of evidence that can be photographed, cast, or collected. But the tarps, two eight-by-ten blue plastic tarps, presented a unique challenge. “Before the academy, I wouldn’t have processed the tarps,” Detective Carnahan told us as we got back into the vehicle to head back to the sheriff’s department. But now, he said, “Instead of looking at things as if we could not process them, we now look at everything as something that can be processed; that broad perspective is what your training provided to us.”
Television has provided viewers, and therefore potential jurors, with the unrealistic expectation that all CSIs are like the ones found in prime time. Unfortunately, that could not be any further from the truth. We have held classes on developing latent fingerprints in which thirty-year veterans in the field had no idea that a fingerprint could be lifted off anything other than something smooth, like a piece of glass. Imagine working crime scenes for thirty years without having the background to know how to develop prints off all types of surfaces? How many more crimes could have been solved?
Looking for a fingerprint on two eight-by-ten tarps (front and back) is like looking for a needle in a haystack. But the only way to find that needle is to look, and look is what Detective Carnahan did. He decided that in order to process the tarps, he needed to superglue-fume them. Common, everyday superglue, dabbed into a small pan and heated, causes the glue to give off gaseous vapors that stick to the ridges of an oily fingerprint and make it more readily visible. On larger items, a fan is sometimes used to help circulate the vapors throughout the container. In order to superglue-fume something, however, the item must be completely contained so that the entire surface area is exposed. Carnahan studied the situation and jotted down a schematic for a large frame that he wanted the maintenance guys at the sheriff’s department to create. The frame would allow the tarp to hang completely inside the container with both sides exposed. The real ingenuity came when, instead of building solid walls, he decided to contain the fumes with plastic wrap—industrial plastic wrap, like the kind used to wrap pallets for shipment on trucks. In essence, Carnahan made a large box using the plastic wrap for the sides. This made it easy to put the tarp and the superglue in the container, along with a fan to help circulate the fumes. It also allowed him to put a test print, his own, on the inside of the plastic to know that the process was working. With his superglue-fuming contraption in place, he simply wrapped the frame tightly and let the tarp fume. This procedure was performed twice, once on each tarp.
“I then simply cut the plastic and removed the tarp,” Detective Carnahan told us as we all walked down the corridor in the sheriff’s department to where all of the evidence is
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