Device detects whiffs of stiffs: sniffer tube offers new way to find where bodies are buried.
Researchers have unearthed a new way to find a buried body. The method can detect trace compounds emanating from decomposing rats months after death.
If the technique also works for human remains, it may help police find hidden graves of victims months after a murder, researchers say. Because the method relies on a superthin, flexible tube to catch faint chemical signatures in air pockets near a corpse, it could be used to detect bodies buried in hard-to-reach areas, such as under concrete slabs.
"There are about 18,000 homicides annually in the United States and 100,000 missing persons, so stuff like this is needed," says forensic scientist Arpad Vass of Oak Ridge National Laboratory in Tennessee.
Currently, corpse-sniffing dogs, ground-penetrating radar and chemical analyses of air and soil can pinpoint buried bodies. But none of these methods work in every situation, says Thomas Bruno of the National Institute of Standards and Technology in Boulder, Colo., coauthor of the study, to appear in Forensic Science International. The new method promises to be specific, sensitive and flexible, Bruno says.
The tube could be inserted in a small hole drilled into a concrete slab or rubble to sniff out bodies buried underneath. "For a bodyburied under a concrete slab, there is nothing else that would work," Bruno says. "Ground-penetrating radar has problems, and you don't have access to the soil to do analyses."
As a corpse decomposes, tissues break down, releasingbits of nitrogen-containing compounds into the surrounding soil and air pockets. These compounds react with a chemical called ninhydrin, causing it to change color. A bluish-purple flush signals a decomposing body. (Ninhydrin is also used at crime scenes to detect sloughed-off skin tissue in fingerprints.)
This method maybe more precise than a cadaver-sniffing dog, Bruno says. "When you get a positive result with a ninhydrin reaction ... you can be pretty confident about the compound that produced it. But if you get a positive response from a dog, there could very well be a cadaver present, but it could also be something else."
To test their method, Bruno and NIST colleague Tara Lovestead built a "little pet cemetery" of rat grave sites. The rats were placed in wooden boxes containing soil and either left on top of the dirt or buried 8 centimeters deep. Researchers collected air by threading a thin tube through holes in the boxes. After five weeks, the probe detected strong signals from all boxes containing dead rats. Rat-free boxes showed very low levels of these compounds.
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|Date:||Aug 28, 2010|
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