An Army scientist uses Raman Chemical Imaging technology to identify explosives left on fingerprints
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ABERDEEN PROVING GROUND, Md. -- A scene decimated by a suicide bomber or an improvised explosive device leaves little evidence of what life was like before its destruction. It does, however, leave traces of life in fingerprints that can be collected by weapons intelligence personnel and analyzed at forensic laboratories to identify the enemy behind the explosion.

"The Department of Defense has adopted battlefield forensics as a capability for future operations, primarily from the counter insurgency operations that have gone on in both Iraq and Afghanistan," said Dr. Augustus W. Fountain III, a senior research scientist at the U.S. Army Edgewood Chemical Biological Center.

"When the Warfighter is confronted with an enemy that's not wearing a uniform, they're shadows that don't follow the normal conventions of a Westphalian state army. So you have to be able to separate the sheep from the goats in that environment, and in many cases, forensics has been very instrumental in identifying a bad actor, or a person who has left significant evidence that builds up into a case file and then gets turn over to local authorities for prosecution."

Imagine if that case file could be filled with hard data in minutes. Using Raman Chemical Imaging technology, Fountain is leading a team of scientists at the Aberdeen Proving Ground to develop a device that could be used by the Warfighter to give a high degree of chemical specificity that would identify the explosive without compromising the fingerprints; used for biometric attribution.

Working with the U.S. Army Criminal Investigation Laboratory, the U.S. Army Research, Development and Engineering Command's chemical and biological center has demonstrated that RCI could be used to collect a biometrically relevant fingerprint image and spatially identify trace amounts of explosives by collecting thousands of wavelengths of scattered light across the magnified images of the fingerprint.

When light interacts with the surface of the sample, it is scattered by molecules both elastically and inelastically, Fountain said. Photons in elastically scattered light do not lose energy and there is no change in wavelength. However, photons in inelastically scattered light result in a net transfer of energy based on the molecule's vibrations and result in a slight change in the wavelength. Measuring the difference between the original wavelength and the scattered wavelength indicates what molecules are present on the surface, he said.

"By knowing and identifying things like the oils in the fingerprint, we can get a rough estimate and a good enough image to feed into AFIS, the Automated Fingerprint Identification System used by the FBI and law enforcement agencies," Fountain said.

"A trained forensic fingerprint analyst can identify who left the fingerprint. Additionally, if chemical residue was left behind, the chemical would be embedded within the ridges of the fingerprint so we can also tell what chemicals that person recently handled," he said.

What used to take hours to identify the fingerprint and determine the trace explosives now only takes a few minutes. That kind of information could help create a body of defendable evidence that builds a case file against a suspect believed to be involved in an IED incident or attack on U.S. Forces. The RCI technology supports the DoD's effort to utilize fingerprinting, facial recognition, retinal scans and other biometric indicators to catalogue a person's history, especially on the battlefield where a threat to soldiers remain high.

Producing positive identification in austere environments in a timely manner better protects soldiers from future attacks by holding accountable those responsible. The leads that analysts verify are pursued by local law enforcement and DoD agencies, but unclean data could prevent authorities from properly tracking evidence. After being deployed to a forensic laboratory in Iraq in 2010, Fountain immediately found himself at a crossroads with the evidence returning from various scenes of terrorist attacks.

"Where does the evidence go? Does it go to biometrics first or chemical analysis? If it went to biometrics, standard forensic methods for pulling out fingerprints would chemically contaminate the sample. If it went to chemical analysis, you could potentially ruin the sample for further biometric analysis. With very small quantities of materiel, you run the risk of losing key information if it goes to one or the other places," Fountain said.

The RCI technology alleviates that risk by creating an alternate way to retrieve both components of vital information: the biological metrics and the chemical analysis. The venture was developed out of an Army Technology Objective that began in 2010. The three-year-old project currently utilizes a commercial RCI unit designed for large scale laboratory analysis and features a multitude of computers, lasers and optical systems necessary to detect traces of explosives on realistic surfaces such as polystyrene, polycarbonate and painted white, black and silver car panels. The successful testing has spurred further work to speed up the imaging process and integrate automatic targeting regions of interests. According to Fountain, the ultimate goal is to make the RCI system field operable as a smaller, ruggedized tabletop unit that can produce accurate forensic analysis for the Warfighter in theater.

The fate of the new model rests on seeking out manufacturing companies that could provide ECBC with the optical design requirements for the equipment. It will also be determined by how user-friendly the upgraded system is for soldiers, many of whom are high-school educated and do not hold advanced degrees like many of the scientists and engineers developing the technology. The ability to detect trace quantities of explosives has become increasingly important in recent years due to several high profile terrorists attacks around the world, and the RCI system advances the DoD effort to bring justice to the battlefield.

"It provides a real capability not only to the Warfighter but to the supporting DoD organizations that support the Warfighter," Fountain said. "I think that's been incredibly rewarding not only for me personally but for the organization as well."

Related Links:

Army Technology Live

U.S. Army Research, Development and Engineering Command

Edgewood Chemical Biological Center