Elemental Profiling of Tire Rubber in Traffic Homicide Cases: A New Forensic Trace Evidence

Between 2004 and 2022, nearly 33,000 fatalities in the United States were linked to hit-and-run incidents, underscoring the urgent need for more precise and detailed analysis of road accident scenes beyond the traditional tire mark analysis. It relies primarily on physical reconstruction of collisions, chemical analysis of rubber residues offers a powerful complementary line of evidence. By examining tire particles and linking them to their original sources, investigators may be able to identify vehicles involved in hit-and-run cases.
Tires vary in composition depending on their brand and model, with each formulation designed for specific performance needs. Moreover, trace elemental contaminants introduced during manufacturing can serve as unique chemical fingerprints, enabling association of tire fragments with their sources. While molecular analysis of rubber has been used for tire type classification, elemental profiling offers a highly sensitive method for distinguishing between manufacturers and models, as well as being able to link tire particles to their original tire.

In this presentation, we will introduce the new concept of using the elemental profile of tire rubber particles from tire marks in a forensic context. From an efficient sampling on the road, isolation from road materials, to the demonstration that tire models are unique and the evaluation of the tire homogeneity leading to new protocols, we show that elemental analysis is once again a powerful tool for traffic homicide investigation.