Single metal deposition (SMD II), a recently proposed method for the development of latent fingermarks, was investigated by systematically altering aspects of the procedure to assess their effect on the level of development and contrast achieved. Gold nanoparticle size, temperature of the deposition solution bath, and orbital shaking during detection were shown to affect the levels of development and contrast obtained. Gold nanoparticles of diameter 15-21nm were found to be most effective for satisfactory visualisation of latent fingermarks, while solutions that were applied at room temperature were found to adequately balance the ratio between the contrast of the fingermark ridge detail and the level of background staining achieved. Finally, optimum levels of development and contrast were obtained through constant agitation of both solution baths at approximately 50RPM throughout the submersion time. SMD II was also tested on a large variety of substrate types and shown to be effective on a range of porous, non-porous, and semi-porous surfaces; however, the detection quality can be significantly influenced by the substrate nature. This resulted in the production of dark grey, white, or gold coloured fingermarks on different surfaces, as well as reversed detection on certain types of plastic, similarly seen through the use of vacuum metal deposition.

This study demonstrates a multi-modal analytical sequence suited to the characterisation of sandy soils, which remain an underutilised form of forensic trace evidence. Within the Swan Coastal Plain in Perth, Western Australia, most soils are heavily leached with only small deviations in their mineral compositions. Their lack of clay and organic matter has led to inorganic methods of analysis predominating, in addition to experimentation with modified techniques. One example is utilisation of the quartz-recovered fine fraction, which is suitable for dry, quartz-dominated sandy soils. In this study, preliminary investigations used the spectroscopic techniques microspectrophotometry, infrared spectroscopy, and x-ray diffraction, to develop a multi-faceted approach for the forensic analysis of the quartz fine fraction of soils. These data were then combined with principal component analysis to demonstrate how chemometrics can assist with objective characterisation and differentiation of sandy soil samples for forensic purposes. Chemometric analysis has not previously been attempted with data obtained from the quartz fine fraction. This methodology is transferable to other jurisdictions where dry, sandy soils predominate.

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