Presenter Information

Lydia Buxa, Liberty UniversityFollow

Category

Poster - Basic

Description

Latent fingerprints found on crime scenes cannot be seen with the naked eye and require development techniques for visualization and analysis (1). Because fingerprints are composed of oily sebaceous secretions, powders used in dusting adhere to the fingerprint oils (2). The fine powder particles help visualize the print increasing contrast of the ridges and minutiae. The most common fingerprint powder is a black powder made of carbon black or powdered acacia. The composition of black powder is far more researched, but the limitation of this powder comes when the latent prints are found on dark surfaces (1). Since black powders would not provide the necessary contrast for photo documentation in this situation, a white-colored powder must be used. However, there are very few literature compositions of white powders developed. The current study then focuses on altering the composition of lanconide, a white powder composed of zinc sulfide (ZnS), zinc oxide (ZnO), barium sulfate (BaSO4), titanium dioxide (TiO2), bismuth oxychloride (BiOCl), and calcium carbonate (CaCO3). The purpose was to improve the standard composition for lanconide powders to enhance latent print development. By removing one of the inorganic salts per trial, seven total powder compositions were tested to see if specific compounds had inhibitory or enhancing effects in the powder. The resulting prints and minutiae were analyzed for clarity to determine which powder provides the best contrast for print photography and analysis. While all powders developed prints, the highest quality resulted from removing TiO2 or BaSO4. More research needs to be done to confirm why these results occurred, but qualities such as acidity, hygroscopicity, solubility, and density were explored.

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Undergraduate

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Apr 17th, 1:00 PM

Altering the composition of lanconide fingerprint powder

Poster - Basic

Latent fingerprints found on crime scenes cannot be seen with the naked eye and require development techniques for visualization and analysis (1). Because fingerprints are composed of oily sebaceous secretions, powders used in dusting adhere to the fingerprint oils (2). The fine powder particles help visualize the print increasing contrast of the ridges and minutiae. The most common fingerprint powder is a black powder made of carbon black or powdered acacia. The composition of black powder is far more researched, but the limitation of this powder comes when the latent prints are found on dark surfaces (1). Since black powders would not provide the necessary contrast for photo documentation in this situation, a white-colored powder must be used. However, there are very few literature compositions of white powders developed. The current study then focuses on altering the composition of lanconide, a white powder composed of zinc sulfide (ZnS), zinc oxide (ZnO), barium sulfate (BaSO4), titanium dioxide (TiO2), bismuth oxychloride (BiOCl), and calcium carbonate (CaCO3). The purpose was to improve the standard composition for lanconide powders to enhance latent print development. By removing one of the inorganic salts per trial, seven total powder compositions were tested to see if specific compounds had inhibitory or enhancing effects in the powder. The resulting prints and minutiae were analyzed for clarity to determine which powder provides the best contrast for print photography and analysis. While all powders developed prints, the highest quality resulted from removing TiO2 or BaSO4. More research needs to be done to confirm why these results occurred, but qualities such as acidity, hygroscopicity, solubility, and density were explored.

 

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