"It is also a non-invasive tool, so the sample remains intact for other analysis or archiving," he says. Volatilization of water, oils and other organic components over time should not hinder print identification since only inorganic elements are detected.
X-ray fluorescence itself is not a new technology. The phenomenon is widely used for chemical analysis, particularly in the investigation of metals, glass, ceramics and building materials, and for research in areas such as geochemistry and archaeology. But this is the first use of MXRF (XRF performed with micrometer-size beam) for fingerprint detection.
In the line of beauty
One of the nation's leading experts on scientific evidence greeted Worley's MXRF work with enthusiasm.
"The beauty of this new visualization technique is that it permits you to visualize the latent without altering it," says Edward Imwinkelried, law professor at the University of California -- Davis and former chair of the evidence section of the American Association of Law Schools.
Any alteration in the visualization stage can distort subsequent stages in the process.
"If the print is altered in visualizing it, it does not matter how accurately the visualized print is recorded -- that image will not be an accurate depiction of the fingerprint impression at the crime scene," he says.
Imwinkelried, coauthor of the third edition of "Scientific Evidence," one of the leading treatises in its field that has been cited on several occasions by the U.S. Supreme Court, recently warned that existing fingerprint matches key to fighting international terrorism and keeping criminals off the street are no longer foolproof.
"We can no longer naively assume the reliability of our current fingerprint standards," he writes in "How We Can Improve the Reliability of Fingerprint Identification," a paper published in a recent issue of "Judicature," co-authored by criminal defense attorney and biometrics expert Michael Cherry, president of Cherry Biometrics. "Given the stakes, not only justice in a particular case but national security itself, we must do better."
Calls for reform
Cherry and Imwinkelried urge reforms.
The first system for classifying and identifying fingerprints was developed in the late 19th century by Sir Francis Galton, known for his famous quote that the odds of two individual fingerprints being the same are one in 64 billion.
Cherry and Imwinkelried are concerned that since the current world population exceeds 6 billion persons -- each usually with 10 prints -- the world population of fingerprints now therefore exceeds Galton's odds.
They also worry that fingerprint matching techniques which once used cards and then analog photographs to compare up to 10 fingerprints have been taken over by computerized systems using less precise digital images, and pre-screen matchers sometimes use only a single index finger.
"If we're going to rely on computer technology for the watch list on terrorism and for background checks ... we've got to have some assurance the computer system is reliably accurate," says Imwinkelried.
He and Cherry call for the high-powered computer analysis of existing fingerprint databases, called data mining, to detect new patterns and develop new criteria for matching fingerprints.
They also recommend the return to the Henry Fingerprint Classification System, which used all 10 fingers to classify an individual. The Henry system, Imwinkelried and Cherry say, would better help identify suspects who use aliases and would prevent criminal suspects, like alleged serial killer Jeremy Jones, from being re-released after each arrest by technical glitches in the FBI system. Jones is accused of committing several murders after he was repeatedly freed following arrests for other minor offenses. Because only one print was used for matching, the fingerprint-matching system failed to detect that he was using an alias.
"If analyzed properly, fingerprints can be as accurate as DNA," the authors say.
In an earlier "Judicature" article, Cherry and Imwinkelried argued for greater skepticism of using computerized fingerprint analysis, especially for its reliance on digitized images of fingerprint patterns.