Development of latent fingerprints on unfired cartridges by palladium deposition: A surface study

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