A trial of the utilization of stable isotope analysis for the estimation of the geographic origins of unidentified cadavers

The number of unidentified cadavers is increasing worldwide and the effective methods which reveal their geographic origin are not well known. In this study, we analyzed the urine stable isotope ratio of hydrogen and oxygen collected from three locations: Chiba (Japan), Fuzhou (China), and Denpasar (Indonesia) from healthy volunteers. In addition, analysis of the effect of drinking bottled water on stable isotope ratios found in urine, and the comparison of the stable isotope ratios of urine and saliva, were conducted. Statistically significant differences in δ2H and δ18O values from the three locations were found. In this pilot study, urine δ18O values became increasingly similar to those of bottled drinking water during an eight-day period of drinking only bottled water. In a separate pilot study significant differences in δ18O, δ13C, and δ15N values from urine and saliva were found, but not in δ2H values. In all three studies, although the number of samples was limited, the results suggest that with further research, stable isotope analysis from urine samples might be used to identify the origins of unidentified corpses, assist in determining the length of time an individual has been in a given area and distinguish between body fluids.