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New forensic method could help police solve crimes


Forensic researchers at FIU have developed a groundbreaking method that can tie a shooter to the ammunition used to commit a crime, giving law enforcement agencies a new tool to solve cases.

Through research funded by the National Institute of Justice and recently accepted for publication in the Journal of Forensic Sciences, chemistry Professor Bruce McCord and doctoral candidate Jennifer Greaux discovered a new technique that identifies the chemical signature of the powder inside a bullet. This unique process can potentially link a suspect to the ammunition fired even if the weapon is not found.

The discovery comes at a time when the conventional method of analyzing gunshot residue is in danger of becoming less reliable, as weapon manufacturers remove lead – one of the three principle elements analyzed today – from their ammunition.

“Crime labs all over the country are faced with the reality that their only way to analyze whether a gun was fired by a suspect may become obsolete,” said McCord, a former forensic analyst for the FBI. “Our discovery is not only more accurate, but it can determine the type of gunpowder used in a crime even if the gun is never recovered.”

Currently, crime labs test the gunshot residue collected from a suspect’s hands and clothes for three elements, barium, lead and antimony. If that residue tests positive for all three and the particles have the correct shape, detectives conclude that their suspect either fired a weapon, held a weapon that had been recently fired or was near a weapon that was fired. But doubt remains – and if a weapon is never recovered from the scene, detectives have no way of using the residue to tie the ammunition to a suspect.

McCord and Greaux’s discovery changes all that.

Instead of testing for just three elements, the scientists focus on the smokeless powder that is found inside bullets to determine their chemical composition. Since each manufacturer has its own specific “recipe” for their smokeless powder, the process in essence defines the type of residue left behind.

“It’s easy to commit a crime,” said J. Graham Rankin, a professor of forensic science at Marshall University and fellow at the American Academy of Forensic Science. “This type of research is making it harder to get away with it.”