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Put some putty on it

Chemistry professor exploring use of putty to collect gun residue samples

There’s no one way to analyze gunshot residue, but in the last seven years of her 34-year-career as a chemist and forensic scientist, Suzanne Bell, a commissioner for the National Commission on Forensic Science, has been working to develop new methodologies that focus on organic residues. 


Current gunshot residue analysis focuses on detecting inorganic residue from the primer, the part of the cartridge case that ignites the powder. Bell’s analysis method examines the organic residue using existing commercial instrumentation already used by airports to screen for explosives.

That’s the reason why she was one of five researchers from across the world invited to meet with the European Network of Forensic Science Institutes (ENFSI) in Krakow, Poland and Weisbaden, Germany in April to discuss developments in forensic gunshot residue techniques.

The only researcher from the United States, Bell spent two days in Europe comparing methodologies and testing different sampling methods with researchers at the Polish Forensics Science Institute in Krakow and the Federal Criminal Police Office in Wiesbaden.

“They are quite progressive in their approach,” she said. “I was humbled to be invited. It was encouraging to see that so many of the main forensic entities there are actively studying new techniques.”

One of the most challenging aspects of analyzing organic residues is sampling. Many of the organic components of gunshot residue cling to skin and some are absorbed by the skin, providing a greater level of confidence when trying to determine if a person has recently fired a weapon.

“The other researchers and I discussed different techniques and instruments,” Bell said. “Do they wipe hands? Do they use different kinds of adhesive or tape?”

Forensic researchers in the Federal Criminal Police Office use TesaTack, putty commonly used to hang posters, to perform sampling. They use the putty to dab the hands after someone fires a gun, then extract the residue from the putty and perform an analysis.

“There are a number of different ways to perform sampling, and they have discovered a great method that we are now working to validate,” Bell said.

After her time in Europe, Bell believes that the Federal Criminal Police Office is close to having new, validated methods.

“They’re almost at the point of having actual, validated methods. They are training others in their laboratories and it encouraged me that we can do the same.”

Bell hopes to continue to advance the methodology for detecting organic gunshot residue and see these methods adopted by the forensic community world-wide. 

Photo Credit: Joana