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Hair dye and fake tattoos provide a new way to catch crooks

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The substance used to make hair dyes and fake tattoos may become the latest tool in the fight against crime.

Curtin University of Technology researchers are developing new fingerprinting technologies using lawsone, a naturally occurring substance found in henna.

Simon Lewis, Associate Professor of Forensic Chemistry, said the new methods being tested had the potential to be an important complementary method to those currently used in fingerprint detection.

According to Curtin PhD student Renee Jelly, lawsone’s properties made it a very useful tool for law enforcement.

“Lawsone is the compound that gives henna its characteristic property for dying hair and skin a reddish brown colour,” she said.

“We have discovered that it reacts with the amino acids in invisible fingerprints on paper, which turn a purple-brown colour when treated with lawsone.

“These coloured fingerprints are also luminescent under a forensic light source.”

Miss Jelly’s thesis, Natural Products as Novel Reagents for the Development of Latent Fingermarks on Porous Surfaces, involves investigating a number of alternative materials to use in hunting for fingerprints on paper.

“Paper-based evidence, such as documents, wrapping material and containers, are frequently encountered in criminal investigations,” she said.

“The most widely used methods for detecting invisible fingerprints on these surfaces rely upon the detection of the amino acids present in natural skin secretions.

“Fingerprints formed in this way can be extremely long lived, with impressions in excess of 20 years of age being developed with amino acid sensitive treatments.

“Lawsone is not the only alternative substance that I have discovered to detect fingerprints on paper, but it is one of the most promising that I am investigating.

“When lawsone reacts with amino acids in fingerprint residues on paper, it leaves coloured ridges that luminesce at longer wavelengths than the reagents currently used by law enforcement around the world, an advantage that may combat the problem of native background fluorescence.

 “This research opens the possibility of a whole class of new treatments that may lead to further improvements in fingerprint detection.”

Miss Jelly, Associate Professor Lewis and their team are also currently testing other compounds.

This research was partly supported by a Curtin Linkage Grant in collaboration with the Australian Federal Police, Forensic Science South Australia, Western Australia Police, and researchers at University of Canberra, Deakin University and the Hebrew University of Jerusalem.

Curtin’s Department of Chemistry recently relocated to new facilities within the Resources and Chemistry Precinct, located on Curtin’s Bentley Campus. At the Precinct the chemistry researchers, including Associate Professor Lewis and his team, have access to some of the most advanced chemistry laboratories in the Southern Hemisphere.

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