2014/07/25

Smithsonian Science July 23 2014: The bones talk: Smithsonian helps Wisconsin police narrow search in 20-year-old mystery

The bones talk: Smithsonian helps Wisconsin police narrow search in 20-year-old mystery

Investigators from Rock County, Wisconsin, are one step closer to solving the mystery surrounding the death of an unknown teenager thanks to Smithsonian scientists.

Christine France, a physical scientist at the Smithsonian’s Museum Conservation Institute, was asked to help pinpoint the region where a white male whose skeletal remains were discovered in 1995 on the bank of Turtle Creek near Clinton, Wis., may have grown up. Police estimate John Clinton Doe, so named because he was found near Clinton, was about 18 years old and had been dead for about one year before his remains were discovered by hunters. He was wearing only one Nike Air sneaker and a T-shirt bearing the logo from the English rock band Venom. France was asked by Wisconsin police “to analyze the stable isotope values in the femur bone from the unidentified individual,” France says.

Oxygen isotope values embedded in bones can indicate the geographical region where a person lived. Harnessing the power of stable isotope analysis, France was able to help police narrow their search to a teenager who likely once lived in Wisconsin, Michigan or Minnesota. While the cause of his death remains undetermined, investigators believe this new information will greatly assist in identifying the boy and hopefully resolving the case. Police have already assembled a long list of missing persons who have been ruled out as this individual.

Finding clues in the isotopes

Isotopes are variants of a particular chemical element. While all the isotopes of a given element, like oxygen, have the same number of protons in each atom, the number of neutrons differs between them. This changing number of neutrons alters the atom weight of each isotope allowing France to calculate an isotope ratio value based on the combinations of atoms of differing weight. “We created a fine powder from a sample of the individual’s femur bone. This allowed us to extract the oxygen isotopes from the bone by separating them into their different weights using our stable isotope mass spectrometer,” France said. more