This article reports on a pilot study that examined the ability of Laser-Induced Breakdown Spectroscopy to sort human bones from 12 individuals.
Commingling of human remains can result from mass disasters, conflicts, epidemics, mortuary ritual, or even curation mishap. Sorting, or reassociation, of large-scale commingling is challenging and requires time, space, and the practiced ability to recognize the indicators necessary for reassociation of remains, especially when the bones are fragmented. Laser-Induced Breakdown Spectroscopy (LIBS) is an atomic spectroscopy method that uses a focused laser to sample materials at the microscale and excite the subsequently atomized matter in the generated micro-plasma, resulting in an elemental profile. It requires no sample preparation, is visually non-destructive, and can detect low atomic weights such as carbon, hydrogen, nitrogen, and oxygen. Portable LIBS is therefore a potentially useful tool for reassociating comingled remains beyond the capacity of other elemental methods, such as the more popularly used portable X-ray fluorescence (XRF). This presentation is a pilot study examining the utility of LIBS analysis for sorting human bones from 12 individuals; six males and females with an average age of 70 years were sampled from the John A. Williams Documented Human Skeletal Collection at Western Carolina University. Results showed that using chemical data reduced from 23,000 variables to 200 principal components, linear discriminant analysis gives a 90 percent or higher accuracy in assigning a bone to its known individual. The average classification accuracy was 95 percent. The next phases of this project will expand the sample size to 60 individuals and include a comparison of human accuracy via a reassociation test using trained, forensic and bioarchaeological anthropologists. (Published Abstract Provided)