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What's in a skeleton? For Wright State University researchers in Dayton, Ohio, the answer is a unique signature.

The researchers are developing a system for scanning "the skeletal structures of people at airports, sports stadiums, theme parks, and other public places that could be vulnerable to terrorist attacks, child abductions, or other crimes," according to the university. "The images would then quickly be matched with potential suspects using a database of previously scanned skeletons."

Caveats are that the researchers are still studying the adult skeleton -- which has 206 bones, if you're keeping track -- to see just how few bones, as well as which ones, could be used to create a unique signature. In addition, they haven't yet hit on the ideal cocktail of x-rays, gamma rays, or other body scanning technologies. So far, current technology requires people to be within about six feet (2 meters) of the scanner.

Latency is another issue. With existing technology, a scan would require approximately 5 seconds, and matching it to a known skeletal signature requires 10 seconds. Radiation from the scan would be equivalent to what a person is exposed to on a cross-country flight -- 2 to 5 millirem -- or somewhat less than half the dose of a chest x-ray. Still, researchers would need to reduce the radiation exposure substantially for the technology to see wide application.

Of course, the larger questions are: Have biometric signatures ever caught a terrorist, child abductor, or other criminal, and how would authorities scan them all, anyway? As security expert Bruce Schneier sarcastically noted on his blog, "every country has a database of terrorist skeletons just waiting to be used."

Rather, the primary application for this technology, if made ready for prime time, would likely be for verifying that the passport someone is carrying belongs to them at borders, or for corporate and government access scenarios, such as "badging in" in the morning.

But Wright State isn't the only university exploring remote biometrics. Researchers at Carnegie Mellon University's CyLab Biometrics Lab, for example, are developing a system, using multiple camera lenses, to read a person's iris when they walk through a portal or doorway, from 8 to 12 meters away.

In a similar vein, two researchers at the University of South Florida -- Sudeep Sarkar and Zongyi Liu (now at Amazon.com) -- have explored using gait recognition, in combination with facial recognition, for identifying people at a distance.

According to Julie Skipper, an associate research professor at Wright State Research Institute, "that's our biggest challenge -- to accurately acquire bone signatures at a distance." She says that for the technology to catch on, government agencies would ideally like to see skeletal recognition from 50 meters away. "If we had that problem solved, we'd be in market right now."