ISU researchers are working on a way to know the time a fingerprint was created.
Researchers at Iowa State University are looking to expand on the information that can be gathered after the whorls, loops and arches of fingerprints are identified.
ISU graduate student in chemistry Paige Hinners, wants to be able to put a time on when a fingerprint was created. She says the idea came out of other research into fingerprint information. It started with people are trying to determine if they can establish age, ethnicity, and gender based on the compounds found in a fingerprint.
Hinners saw the degradation of chemicals could possibly give a timestamp for fingerprints. “What I originally set out to do was to use a physical and chemical method –so we use mass spectrometry imaging — meaning we get a chemical profile and a spatial profile — so I could actually see where the chemical is on the fingerprint ridges,” according to Hinners. So, what I wanted to look at was how the compounds in the fingerprint ridge diffused with time.”
She says the early research has shown they can create a chemical image of the print. “The older the fingerprint got, the more I lost the fingerprint ridges in my chemical image. And so, that’s kind of what led us into looking at what was happening in those compounds,” Hinners says.
Hinners says everyone has a couple of different types of chemicals in their fingerprints. “There can be both sweat-based, and then kind of like grease-based residues in your fingerprint. So, when you touch a surface you’re leaving a combination of that behind,” Hinners explains. “And the oily portion actually comes from you touching your face, touching your hair, touching other areas of your body where you have sebaceous glands and those secret lipids and it’s more oily. You touch glass and you see a fingerprint on there — you are leaving some of that material behind.”
Hinners says they’ve done a small survey of fingerprints kind of as a proof of concept. “We just did a study from fresh through seven days age. So, even by one day age, we were able to tell that those fingerprints had been exposed to an ambient environment, and they were no longer fresh,” Hinners says.
The research confirmed that ozone in the air was causing the degradation of the unsaturated fats in fingerprints. Hinners says knowing when a fingerprint was left can help in narrowing when someone was at a crime scene. “If you’ve ever heard the defense ‘I was there the week prior.’ So this kind of just assists in locking down and says ‘yes’ this fingerprint is from within the crime window — so we know it happened during this time — and the fingerprint also came from this time,” Hinners says. She says it could also be helpful if you don’t have a suspect and can tell that one set of fingerprints was left during the time of the crime and rule out others.
Hinners says there needs to be a lot more study with a larger test pool of fingerprints to move toward making a time determination on a fingerprint something that can be used in a case. “To get something presented in court is a very difficult task. It has to meet many different standards. And I think the very broad team is it has to be generally accepted by the scientific community,” she says.
A National Institute of Justice grant is supporting the research.