Profiling of blood volatiles on carpet.

Abstract

The characterization of the complex mixtures of volatile organic compounds (VOCs) emitted during human decomposition (“The smell of death”) has high potential for forensic investigations and human rescue. Currently, human search and rescue operations are commonly carried using rescue dogs. Even though they are well trained for the detection of body decomposition, their result is not accepted in a court of law else a body is subsequently found. Using on- or off- site chemical detectors as well as dogs could provide admissible evidence in court. Moreover, a better understanding of the chemicals responsible for the “smell of death” could further improve the efficiency of dog training and possibly provide a measurement of certainty in their response. In order to operationalize a new method for detecting VOCs emitted by decomposing bodies to be used by law enforcement agencies, the profile of human decomposition needs to be established. Thanks to the close collaboration with the University Hospital Center (CHU) it was possible to obtain human blood samples. Using human blood has the advantage of getting the closest to the “smell of death” without the legal and ethical difficulties of using whole bodies or the hassle of justifying the similarities between animals and humans. This work was inspired by forensic case work such as the Casey Anthony trial. Police investigators often come across cases in which a body has been in contact with a carpet before being placed elsewhere. It can either be a body wrapped in a household carpet or simply transported in the trunk of a car. This study aims to characterize the volatile signature of blood residues on different carpet types in order to extract the VOCs of interest responsible for the so called “smell of death”. The headspace of the different samples was monitored by thermal desorption (TD) and comprehensive two-dimensional gas chromatography coupled with high resolution time-of-flight mass spectrometry (GC×GC- HRTOFMS). To the best of our knowledge, this study is the first to investigate the influence of carpets on blood decomposition VOCs. The compounds of interest found for both the blood decomposition and carpet VOCs will be compared to those listed previously in the literature.