Nanotrace: Applications of subvisible to nanoscale particles in trace evidence

As submitted by the proposer: Nanoparticles and other subvisible particles (10 nm to 100 µm) are present in nearly all forms of existing trace evidence, yet the overwhelming majority of trace examinations focus exclusively upon larger particles. In an era where highly engineered nanoscale materials are being introduced at increasing rates, it seems inconceivable that such materials are not being regularly examined as forensic evidence. The goal of this research is to systematically develop approaches for the isolation, analysis, and interpretation of particles in this size range, which would effectively equate the sensitivity of trace evidence to that of DNA analysis. While the smallest particles in this range will require higher resolution instrumentation, the majority of these particles can be characterized effectively by applying the suite of microanalytical methods present in most trace evidence laboratories today (stereomicroscopy, polarized light microscopy, and scanning electron microscopy). The initial phase of research will focus on assembling a list of subvisible particles and information about their properties and sources. Particles on this list will then be ranked to identify those particles that contain diagnostic micro- or nanoscopic properties and are likely to be encountered as trace evidence. Physical samples of the top one hundred particles will then be characterized by a range of microanalytical methods. This data will be examined to define the most diagnostic features of each particle type as well as the preparation methods and instrumental approaches that most efficiently provide this information. From this data, an electronic atlas of subvisible particles will be prepared. In addition, this research will evaluate evidence collection techniques and their sensitivity to the recovery of particles in this size range. Finally, the collection and identification methods developed will be tested against typical trace evidence substrates (e.g.¸fabrics, GSR stubs) to evaluate the prevalence of subvisible particles and the effectiveness of various methods for identifying these particles. The results of this research will benefit the immediate state of trace evidence examinations by providing laboratories with guidance for the collection, isolation, analysis and interpretation of subvisible particle evidence. It will provide laboratories that are not necessarily searching for subvisible particles, insights into the way current collection methods could impact the preservation of subvisible evidence for future examination. In the long term, this research will provide a firm foundation for the development of an entirely new category of trace evidence. This project contains a research and/or development component, as defined in applicable law. ca/ncf