When it comes to the sad task of finding human remains, cadaver dogs can achieve impressive feats. For this, they make use of their highly developed sense of smell. Usually, unspecific odor compounds are used in training these service dogs, which can result in false positives, e.g., when they encounter an animal carcass. Finding smells specific to the decomposition of human remains could improve the training and success rates of cadaver dogs, as well as allow the development of analytical equiment capable of finding corpses.

Eva Cuypers, University of Leuven, Belgium, and colleagues have analyzed the profile of volatile organic compounds (VOCs) emitted by both animal and human remains. They let the samples decompose over a period of six months, and analyzed the surrounding air using a thermal desorber combined with gas chromatography, coupled to mass spectrometry (TD-GC/MS).

The researchers found 452 different VOCs across a wide range of chemical classes, including esters, ketones, ethers, alcohols, and aldehydes. While is was not possible to separate the human samples from all animal remains, eight compounds were found to be specific for either human or pig: diethyl disulfide, methyl(methylthio)ethyl disulfide, 3-methylthio-1-propanol, pyridine, ethyl propionate, propyl propionate, propyl butyrate, and ethyl pentanoate.

Pig and human tissue show very similar decomposition, which supports the use of pig remains as analogues for human tissue. However, in this study, pig remains could be told apart from human remains based on five different esters. The team aims to further investigate this aspect and find a human specific marker, which could benefit a range of forensic disciplines.

• The Search for a Volatile Human Specific Marker in the Decomposition Process,
  Mohana Krishna Reddy Mudiam, E. Rosier, S. Loix, W. Develter, W. Van de Voorde, J. Tytgat, E. Cuypers,
  PLoS ONE 2015, 10, e0137341.
  DOI: 10.1371/journal.pone.0137341