A Comparison of Physical Developer Formulas

Although the process is time consuming, using Physical Developer when other methods have failed could be the factor that helps solve a case. On porous materials, a reaction occurs between the lipids, fats, oils, and waxes found in sebaceous sweat and the silver-based liquid reagent known as Physical Developer (PD) to produce a silver-gray deposit visible to the naked eye. Since these sebaceous components are not soluble in water, the PD latent print development technique is particularly useful on wet paper or paper that has previously been wet. When the amino acids in fingerprints have been washed away or failed to react with Ninhydrin, 1,2- Indanedione, or DFO; processing with PD may still produce identifiable latents. However, PD is time-consuming, expensive, destructive, and has a short shelf life. Therefore, one should only utilize PD as a final process in circumstances where it will be the most effective. This preliminary study consists of comparisons made by the Canyon County Sheriff’s Office Crime Lab in Caldwell, Idaho between a commercially, premixed PD kit and PD prepared in the laboratory. In addition to price determinations, three different types of paper were subjected to extended periods of environmental conditions prior to processing. MATERIALS AND METHODS The paper samples consisted of white printer paper, yellow lined notebook paper, and newspaper touched by several donors with their fingers and palms. One donor applied a full palm print to the center of each paper while the other