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Forensics - The telltale tree

Logs confiscated by police at a Texas murder scene and the work of a scientist at Oak Ridge National Laboratory may help put a killer behind bars. Using a technique called laser-induced breakdown spectroscopy, Madhavi Martin obtained "chemical fingerprints" from a partially burned log at the crime scene and compared them to those of logs that had been placed by the suspect in a fireplace. "We used our laser technique to determine the elemental makeup based on heavy metals and other trace elements to evaluate whether the two sets of logs could have come from the same tree," Martin said. She and the University of Tennessee's Henri Grissino-Mayer concluded that the two samples matched. Had the wood come from different trees the chemical fingerprints would have been different. Laser-induced breakdown spectroscopy is a technique that Martin and ORNL's Stan Wullschleger originally used for carbon sequestration applications such as determining the amount of carbon in soil. Since then, the technique has also proved useful for identifying chemical fingerprints in bones and for detecting counterfeit currency. The research is funded by the Department of Justice and ORNL's Laboratory Directed Research and Development program.