Traditional DNA analysis from crime scenes can be complex and expensive. However, researchers at the University of New Hampshire (UNH) have developed a promising new method that’s easier and cheaper to use. This new test focuses on “touch DNA,” which is genetic material left behind through casual contact.

The importance of this research lies in differentiating between primary DNA transfer (from the perpetrator directly touching an object) and secondary/tertiary transfer (DNA transferred indirectly through contact with someone or something else).  Mistakenly identifying secondary DNA as primary DNA has led to wrongful accusations in the past.

The UNH team’s method utilises a more affordable and accessible technique called qPCR.  In their study, published in the Journal of Forensic Sciences, they tested their protocol by having volunteers hold objects like a gun grip and coffee cup.

The results were encouraging:

– Male and female DNA were found together on the gun grip in 71% of trials, indicating successful detection of primary transfer from both volunteers directly touching the object.

– Male DNA was found on the female volunteer’s hand in 50% of trials, suggesting secondary transfer from the gun grip.

– Male DNA appeared on the coffee cup 27% of the time, hinting at tertiary transfer (transferred from gun grip to hand to cup).

“This new test can help prevent innocent people from being wrongly implicated in crimes,” said Samantha McCrane, a researcher involved in the study.  She highlights the dangers of misinterpreting touch DNA transfer.

The study also explored how factors like age, ethnicity, and skin conditions might influence DNA transfer. Ethnicity and age seemed to have minimal impact, while the limited data on skin conditions wasn’t conclusive.

The researchers acknowledge the need for further investigation. Currently, even experts struggle to distinguish between different types of DNA transfer.  This new, inexpensive protocol offers a valuable tool for gathering more data and conducting larger-scale studies in the future.

Journal Article:

Ray, Robbin, “New Simpler and Cost-Effective Forensics Test Helps Identify Touch DNA” (2024). UNH Today Newsroom. 5548.

https://scholars.unh.edu/news/5548

Note: Content has been edited.