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Dec. 19, 2011

Recovering Fingerprints on Fabrics

by Mariel Emrich

Click to enlarge images

By Mariel Emrich, Columbia Grammar and Preparatory School

A 21-day sample on nylon demonstrating palmar flexion creases. (Credit: University of Abertay Dundee/Scottish Police Services Authority)

Earlier this year, forensic experts at the University of Abertay Dundee and the Scottish Police Services Authority (SPSA) discovered a technique to recover fingerprints on fabrics. This technique is known as vacuum metal deposition (VMD). It uses gold and zinc to recover the fingerprint mark that is on a piece of fabric. In the past, VMD has been used to detect fingerprint marks on smooth surfaces, such as carrier bags, plastics, and glass. In fact, it was invented in the 1970’s. However, it was never used on fabrics until 2011.

The researchers at SPSA realized the value the VMD technique could bring to a police investigation. The process starts by placing fabric into a vacuum chamber and spreading a fine film of gold over the fabric. Next, forensic investigators heat up zinc, which attaches to the gold where there are no fingerprint residues. So where there are fingerprint ridges there is no zinc, revealing a clear outline of the fingerprint.

One researcher at SPSA said in statement: "The research is still in its early stages but we are starting to see results. We have shown that fabrics with a high thread count are best for revealing a print and have recovered identifiable fingerprints on a number of fabrics including silk, nylon and polyester." Only 20% of the public is considered a “good donor” for leaving fingerprints. Therefore, while the success rate is still low for recovering a full fingerprint from items of clothing, the researchers have had success in revealing the shape of a fingerprint on many different fabric types.

This breakthrough is key to the forensics world because it can help determine if a suspect is innocent or guilty. This extra piece of evidence could potentially solve many cases because it helps police frame a sequence of events and could be used to provide evidence in cases where someone was pushed or grabbed in a particular part of their clothing. In addition, this technique could narrow down the list of suspects who then might be convicted on DNA or other forensic evidence. As the VMD technique is incorporated into Fingerprint Recognition Technology, the Ability to Verify Rate (ATR) will increase. This provides a more solid and believable argument for court.

For more information:
VMD Technique Used to Trace Fingerprints on Fabrics
Forensic Breakthrough: Recovering Fingerprints on Fabrics can Turn Clothes Into Silent Witnesses
Acquiring Fingerprints From Fabric

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Mariel is currently a sophomore at Columbia Grammar and Preparatory School in New York City. She loves learning about science and particularly enjoys genetics, cancer research, radiology, and forensics.

About Mariel Emrich

The views expressed are those of the author and are not necessarily those of Science Friday.

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