What’s a criminal’s worst enemy? The burly police officer running his rounds? The metal teeth of a police dog ready to bite? How about a bottle of household vinegar? No, it’s not a new episode of CSI — it’s a new research project in the Department of Chemistry at The University of Tennessee.
Researcher and professor of chemistry Mark Dadmun has been awarded a grant of $126,000 to study the chemistry behind fingerprints, and so far the results are pointing toward vinegar, or acetic acid, for use in developing fingerprints.
“We’re testing ideas to see what works,” Dadmun said. “The most promising is taking the fingerprint and exposing it to vapors of acetic acid, which is essentially vinegar. We’re not exactly sure why this happens.”
The grant was awarded to UT by the U. S. Department of Justice after Dadmun presented his research proposal.
The research is based around gaining a better understanding of fingerprinting and obtaining more accurate and consistent results of developing prints.
“The main thing we’re shooting for is trying to make it so any print we receive, we can find it and develop it,” Dadmun said. “Prints are usually invisible. You have to do something to it to make it visible like developing it, like you would develop a picture.”
The project started with Linda Lewis, a researcher at ORNL’s Chemical Sciences Division, who started the research for the Federal Bureau of Investigation 12 years ago upon a request from the U.S. Department of Energy.
“During the effort I discovered that acetic acid basically regenerated fingerprints that would otherwise not have taken,” Lewis said. “So we started a research project for the FBI and the National Institute for Justice in which (we) developed and optimized an acetic acid regeneration method for these fingerprints,”
Previously, investigators used a 20-year-old technique to develop prints by putting an object with a faded fingerprint on it over a heated plate of superglue. As the fumes of the glue reach the print, it begins to visibly rebuild itself. A fingerprint is made of sweat and oil that have parts called carboxylates, and scientists believe these carboxylates are the catalysts for the superglue growth on the print.
Researchers have not yet made a definite conclusion about what is going on within a print. They know the process works better in a humid environment and have assumed water is a key element to the fingerprint “growth.”
“Once we got into the study, we found there was a variable we hadn’t considered that was very important to make this work — and that was humidity,” Lewis said.
Lewis also said that to optimize the study, they regenerated the prints during the summer.
“We also wanted to study the prints again the next summer, so we saved some prints for eight months until the humidity increased again,” Lewis said. “When we regenerated the prints they were incredibly fresh-looking fingerprints.”
But Dadmun’s research is finding that water may not be the key ingredient.
“It’s not the water,” Dadmun said. “Water probably plays a role when you’re using superglue as a glue, but as a vapor, there’s some other mechanism.”
Carboxylates also break down very easily and swiftly under the ultraviolet rays of the sun. So old, worn prints have been a huge problem for investigators. This is where the acetic acid comes in to play. Acetic acid also has a carboxylates group in it, which might actually help replenish the carboxylates that make the fingerprint visible.
Dadmun said he has seen positive results from the tests that he’s run in conjunction with ORNL and the North Carolina Bureau of Investigation. Lewis also reported positive results from other researchers with whom she has talked.
“After talking to people, who have taken our research and tweaked it in the lab, they say that they’ve gotten it to work,” Lewis said. “But we’re still trying to make the research more robust.”
Dadmun said the long-term goal of the research is to eventually create a method for achieving very consistent results, which will make fingerprints visible as close to 100 percent of the time as possible. A breakthrough like this could mean a new horizon for crime investigators and law enforcement alike, and a new household enemy against criminals.
