Forensic palynology in a fatal hit-and-run investigation: comparative soil trace evidence from mechanically corresponding vehicle components

Forensic palynology examines pollen and other palynomorphs recovered from evidential materials in support of criminal investigations. This study reports a comparative palynological examination of soil residues recovered from two mechanically corresponding vehicle components in a fatal hit-and-run case. Soil traces retained within protected internal cavities were processed using an acetolysis-based protocol and examined by transmitted-light microscopy. Fourteen palynomorph taxa were identified in the questioned sample and eleven in the reference sample. Comparative analysis using the percent similarity (Renkonen) index yielded a value of 86.5, indicating substantial overlap in taxonomic composition and relative frequencies. Graphical comparison of taxon-level distributions likewise showed broadly similar patterns and limited between-sample variability. The findings support the proposition that the two soil traces are associated with a shared transfer context rather than representing unrelated environmental accumulations. Considered alongside the mechanical fit examination, the palynological findings provided an independent and complementary source of associative trace evidence. This case illustrates the practical value of forensic palynology in vehicular investigations and demonstrates that meaningful comparative interpretation can be achieved even where only limited quantities of soil trace material are available.