The research department at The Bode Technology Group has developed and used molecular methods to identify individual plant species from a mixture of plant trace evidence material. DNA is extracted from the particulate material collected from evidence such as clothing, packages, building dust, air filters, soil and carpets. The collected DNA is a mixture from the plants associated with the physical evidence. This technique relies on separating the mixture of plant DNA by PCR (Polymerase Chain Reaction) and cloning the PCR product, followed by direct sequencing of the clones. At least two molecular markers have been used to identify plants in evidentiary mixtures, including the internal transcribed spacer (ITS) regions of the ribulose 1-5biphosphate carboxylase gene (rbcL). ITS is a nuclear encoded ribosomal gene and rbcL is a chloroplast encoded gene. Genbank, a sequence database, contains thousands of sequences for ITS and rbcL, as well as other genes. By using data in Genbank in addition to other analytical methods, plants can be identified. The characterization of plants in trace evidence can provide new information for investigations.

With these methods, The Bode Technology Group has recovered individual plant sequences from trace evidence that can be compared to plants associated with a crime scene or provide insight into the geographic origin of the evidence item. These include species of algae, evergreens, flowering herbs, grass, shrubs and trees. Depending on the sample composition, a range of one to many different sequences can be recovered. Based on the ecology and habitat of the plants identified with these sequences, the geographic location can be inferred. The level of precision to which a sample's origin can be identified is most often influenced by the rarity and combination of plants recovered. This combination of plants provides a description for a sample that can match or exclude reference samples from a crime scene or other evidentiary materials.