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Henna points finger at criminals

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Renee Jelly

Phd student Renee Jelly.

The ‘eureka moment’ for Renee Jelly occurred when she considered how some natural dyes like henna – known for its use in temporary tattoos – can stain human skin.

This gave the PhD student from Curtin’s Forensic and Analytical Chemistry Group the idea to test the dyes on fingerprints to see if a wider range of tools could be developed for crime scene investigators.

“The active ingredient that (allows) henna (to) dye skin is thought to be a chemical called lawsone and I wondered if it would react with fingerprints on paper,” Ms Jelly said.

“We tested it and discovered that it does, and turns them a purple-brown colour.”

Police have been lifting fingerprints from smooth surfaces such as glass since the 1890s.

However, things get tricky when crime scene investigators try to visualise prints from porous surfaces like paper.

Techniques have been developed to do this. But the dyes analysed by Ms Jelly produce a darker colour, with better visual contrast and visibility in a wider range of light than currently used compounds.

The Australian Federal Police, Forensic Science South Australia and WA Police have worked with Ms Jelly to ensure the new developments fit the needs of forensic teams.

Her supervisor Simon Lewis says the research is not about replacing existing fingerprinting technologies.

“It’s about offering a range of complementary fingerprint reagents that are different colours and luminesce at different wavelengths,” Associate Professor Lewis said.

“The police need a broad range of options depending on the nature of the surface, the age and condition of the fingerprint, and any background interference.

“So we’re not trying to replace the tools in the toolbox.

“We’re aiming to increase the number and variety of tools available to the forensic investigator.”

Based on story in CITE by KITTY DROK

Photo: JAMES ROGERS

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