Statistical data analysis of bacterial t-RFLP profiles in forensic soil comparisons

Soil can play an important role in forensic investigations in linking suspects or objects to a crime scene. Bacterial populations are one of the biotic parameters in soil which can be used for comparisons. Terminal restriction fragment length polymorphism (t-RFLP) is used to visualize these populations. Here we present a method to compare soil t-RFLP profiles based on Bray-Curtis distances. We developed a decision model to predict the possible common source of unknown samples. Test cases in cooperation with the Police Academy of the Netherlands were used to validate the decision model. The results of these test cases are very promising, indicating that bacterial profiling is a useful additional tool in forensic soil comparisons.