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Hair analysis offers new crime-fighting clues

Hair analysis offers new crime-fighting clues

Scientists can now tell where in the United States a person may have been by analyzing a single strand of hair, offering a new tool for crime investigators trying to identify a body or track criminals.
They said variations in hydrogen and oxygen isotopes found in hair could be matched to the regional tap water people drank, providing clues about where a person had been living.
"In people with very long hair, you could get quite a long history," said University of Utah geologist Thure Cerling, whose findings were published in the journal Proceedings of the National Academy of Sciences on Monday. The tool would work best on hair samples taken from the head because hair grows continuously there.
Cerling and University of Utah biology professor James Ehleringer developed an elaborate map that details regional differences in the hydrogen and oxygen isotopes based on tap water samples from 65 cities in the United States.
Ehleringer's wife and a friend gathered samples from cities with 100,000 or fewer people to ensure that hair samples were from local residents rather than tourists.
"With the whole U.S. blanketed with samples of drinking water, we can see in the drinking water where the big gradients are," Cerling said.
Isotope signature
Cerling said drinking water left an isotope signature in the growing hair. Even people who drink bottled water still use tap water to make coffee or tea or cook pasta, he said. "You really do use a lot of local water in your everyday activities."
The researchers said isotope concentrations in drinking water varied because of regional differences in rainfall and evaporation. Cerling said researchers could probably tell the difference between Utah and Texas, but not necessarily between Chicago and Kansas City.
The researchers said the work had generated a lot of interest from police, but Cerling said the tool could also be used in anthropology and archaeology. "I also think it will have some interesting applications in wildlife conservation," he said.


Updated : 2021-03-01 03:57 GMT+08:00