UK researchers extract drug residue from gel-lifted fingerprint biometrics

A new breakthrough in a familiar technology could help researchers use fingerprint biometrics to solve cold cases. A press release from Loughborough University says a team of analytical scientists has demonstrated, for the first time, how to detect drug residue on gel-lifted fingerprints.

This is particularly significant for sexual assault investigations, since one of the drugs in question is the sleeping pill Zolpidem, which has been used to spike drinks. The team was able to use a gelatine surface to lift Zolpidem-laced fingerprints from glass, metal, and paper surfaces in a lab setting.

“This is the first time that analysis of gel-lifted prints for a drug substance has been accomplished and shows that lifted prints and other forensic marks can be interrogated for useful information,” says Dr. Jim Reynolds, a specialist in analytical chemistry, who led the research. “Since gel-lifted prints and marks can be stored for many years, the technique could be of real use in cold cases where additional information may prove useful to either link or exonerate a suspect to the investigation.”

Gel lifters are widely used by forensics investigators globally. But drug testing has been unreliable because of its inability to distinguish between different types of chemicals. Together with Dr. Ayoung Kim, Reynolds deployed a method called sfPESI-MS, which uses a rapid separation mechanism to distinguish drug residue from the chemicals in the gel used to lift the fingerprint biometric.

The new process employs mass spectrometry to identify the chemicals by measuring their molecular weight. Chemicals are extracted from the gel lifter in tiny liquid droplets, then ionized to activate or deactivate an electric charge, depending on their chemical properties. Because drug residue in the fingerprint is more surface active than the gel chemicals, it can be separated.

Reynolds says the research focuses on Zolpidem – “this could be useful to detect individuals who have been spiking drinks, for example, if the drug they are using gets onto their fingertips, then they will leave evidence at the scene.” But he also foresees expanded use cases for the technique in the future, including the detection of other chemicals such as explosives, gunshot residues, paints, and dyes. The team has plans to work with law enforcement agencies to identify cases in which an analysis of stored gel-lifted prints could help unsolved crimes.

Reynolds and Kim’s research was published in the Drug Testing and Analysis journal, and can be accessed in full on the journal website.

Article Topics

biometrics research  |  criminal ID  |  drug detection  |  forensics  |  latent fingerprints  |  law enforcement