HOMICIDE FORENSICS: CONCRETE TECHNOLOGY GIVES POLICE A NEW TOOL

American Petrographic Services, Inc (APS) was contacted by the Las Vegas, Nevada, Metropolitan Police Department, Homicide Division, to explore the possibility of applying specialized concrete forensic science in an unorthodox setting to help unravel a homicide case. Until then, the investigation had been stymied by lack of detailed information to identify the victim of a crime at least one year old.

When human remains were found in a shallow desert grave, police knew that identification of the victim would be challenging due to exposure to the elements and deterioration of the remains. But in this bizarre case, a concrete sarcophagus entombing the body presented a new potential source of information, albeit one which police had little experience with forensically.

APS geologists and engineers found themselves immersed in a project where the concrete could be a crucial witness. In reports for the Las Vegas Police, APS provided important information on the age and type of concrete used and details about the manner in which the sarcophagus was made.

The most important APS contribution was being able to narrow significantly the estimate for the post-mortem interval (death to discovery). The company's estimate was more precise and therefore more valuable to investigators than the estimates provided by their leading forensic experts. Using the more precise information, police were able to identify the victim as a 17-year-old female reported missing within the APS time line. With the identification, they now have an arsenal of clues to use in the pursuit of her assailant.

To our knowledge, the APS project was the first ever of its kind to use concrete technology in a homicide investigation. Techniques such as analyzing paste porosity and hydration conditions were creatively retooled to analyze entirely different inquiries than the standard construction materials scenarios. All of this work was done (by APS) without the benefit of a body of research related to the effects of decomposing human bodies on the geo-chemical properties of concrete.