Fingerprints provide clues to more than just identity

Fingerprints can reveal critical evidence, as well as an identity, with the use of a new technology developed at Purdue University that detects trace amounts of explosives, drugs or other materials left behind in the prints.

The new technology also can distinguish between overlapping fingerprints left by different individuals - a difficult task for current optical forensic methods.

A team led by R. Graham Cooks, Purdue's Henry Bohn Hass Distinguished Professor of Analytical Chemistry, has created a tool that reads and provides an image of a fingerprint's chemical signature. The technology can be used to determine what a person recently handled.

"The classic example of a fingerprint is an ink imprint showing the unique swirls and loops used for identification, but fingerprints also leave behind a unique distribution of molecular compounds," Cooks said. "Some of the residues left behind are from naturally occurring compounds in the skin and some are from other surfaces or materials a person has touched."

The team's research will be detailed in a paper published in Friday's (Aug. 8) issue of Science.

Demian R. Ifa, a Purdue postdoctoral researcher and the paper's lead author, said the technology also can easily uncover fingerprints buried beneath others.

"Because the distribution of compounds found in each fingerprint can be unique, we also can use this technology to pull one fingerprint out from beneath layers of other fingerprints," Ifa said. "By looking for compounds we know to be present in a certain fingerprint, we can separate it from the others and obtain a crystal clear image of that fingerprint. The image could then be used with fingerprint recognition software to identify an individual."

Researchers examined fingerprints in situ or lifted them from different surfaces such as glass, metal and plastic using common clear plastic tape. They then analyzed them with a mass spectrometry technique developed in Cooks' lab.

Mass spectrometry works by first turning molecules into ions, or electrically charged versions of themselves, so their masses can be analyzed. Conventional mass spectrometry requires chemical separations, manipulations of samples and containment in a vacuum chamber for ionization and analysis. Cooks' technology performs the ionization step in the air or directly on surfaces outside of the mass spectrometer's vacuum chamber, making the process much faster and more portable, Ifa said.

The Purdue procedure performs the ionization step by spraying a stream of water in the presence of an electric field to create positively charged water droplets. Water molecules in the droplets contain an extra proton and are called ions. When the charged water droplets hit the surface of the sample being tested, they transfer their extra proton to molecules in the sample, turning them into ions. The ionized molecules are then vacuumed into the mass spectrometer to be measured and analyzed.

Researchers placed a section of tape containing a lifted fingerprint on a moving stage in front of the spectrometer. The spectrometer then sprayed small sections of the sample with the charged water droplets, obtaining data for each section and combining the data sets to create an analysis of the sample as a whole, Ifa said. Software was used to map the information and create an image of the fingerprint from the distribution and intensity of selected ions.

Additional co-authors of the paper are Nicholas E. Manicke and Allison L. Dill, graduate students in Purdue's chemistry department.

Source: Purdue University

Related stories:

Engineered killer T cell recognizes HIV-1's lethal molecular disguises
Researchers at the University of Pennsylvania School of Medicine and colleagues in the United Kingdom have engineered T cells able to recognize HIV-1 strains that have evaded the immune system. The findings of the study, published online in the journal Nature Medicine, have important implications for developing new treatments for HIV, especially for patients with chronic infection who fail to respond to antiretroviral regimens.
Gold nanostar shape of the future
Rods, cones, cubes and spheres – move aside. Tiny gold stars, smaller than a billionth of a meter, may hold the promise for new approaches to medical diagnoses or testing for environmental contaminants.
Fingerprint analysis technique could be used to identify bombmakers
University of Leicester experts have held discussions with military personnel in Afghanistan following the discovery of new technology to identify fingerprints on metal.
Genes could solve pollution mysteries
(PhysOrg.com) -- Researchers at the University of California, Berkeley, have for the first time identified environmental pollutants by looking at the genes of a small, freshwater crustacean. This new gene-based technique could lead to better and faster lab tests for pinpointing pollutants in contaminated ecosystems.
Mining for Molecules in the Milky Way
Scientists are using the giant Robert C. Byrd Green Bank Telescope (GBT) to go prospecting in a rich molecular cloud in our Milky Way Galaxy. They seek to discover new, complex molecules in interstellar space that may be precursors to life.
NIST shows on-card fingerprint match is secure, speedy
A fingerprint identification technology for use in Personal Identification Verification (PIV) cards that offers improved protection from identity theft meets the standardized accuracy criteria for federal identification cards according to researchers at the National Institute of Standards and Technology.
Microchip fingerprints used to lock out chip pirates
Pirated microchips -- chips stolen from legitimate factories or made from stolen blueprints -- account for billions of dollars in annual losses to chipmakers.
New technology identifies warped fingerprints at warp speed
Researchers at the University of Warwick have devised a means of identifying partial, distorted, scratched, smudged, or otherwise warped fingerprints in just a few seconds.

News discussion:

General Science news