DEVELOPMENT OF LATENT FINGERPRINTS ON UNFIRED CARTRIDGES BY PALLADIUMDEPOSITION - A SURFACE STUDY

Visualized fingerprints on unfired brass cartridge cases developed by a novel method of palladium deposition were examined by Anger electron spectroscopy (AES), scanning electron microscopy (SEM), and electron probe microscopy (EPMA). In spite of the strong contrast of colors bet ween the ridges and the valleys of the developed images, which suggest s a selective coating of palladium on the valleys, palladium was found to deposit onto both valleys and ridges. Lumps of organic material we re scattered mostly along the ridges. The study suggests a model for t he deposition of metals on brass cartridges on which sebaceous fingerp rints were impressed.