As was recently reported in Time Magazine and the Los Angeles Times, scientists have a new way of determining where a person has lived by analyzing a strand of human hair, a technique that could prove helpful in tracking down criminal suspects or unidentified murder victims.
It's based on chemical variations in drinking water from one geographic location to another, and how those chemicals can turn up in the hair of people who drank the water in those areas. Professors Thure Cerling and James Ehleringer at the University of Utah, co-founded Isoforensics, Inc. to use stable isotope analysis of forensic substances to find slight variations in chemical elements' various isotopes. "Hair is a good trap for all those things flowing through the blood system," says Ehleringer. Cerling added, "You are what you eat and drink, and that is recorded in your hair."
Their collection methods were a bit quirky, but effective. They took tap water samples from 600 U.S. cities and constructed a map of the regional differences, then verified the accuracy of their map by testing 200 hair samples collected from 65 small-town barber shops. But not all hair is created equally forensically, as the longer the hair, the greater the possiblity for information. Long hair can provide police with a 2-3 year history, whereas short hair may only reveal three to six months.
Hair analysis has already been used in one cold case by Todd Park in Salt Lake City. Chemical testing on a partial skull showed in the two years before the victim's death she moved about every two months, staying in the Northwest. Alhough the test could not be more specific than somewhere between eastern Washington and Oregon and western Wyoming, Detective Park said, "It's still a substantial area, but it narrows it way down for me." Cerling agrees, saying "This analysis can eliminate about 90% of the U.S. as a possibility" and that "The ability to exclude is just as powerful as the ability to include in forensic science."
