. Chemical reagents which target-specific components or general classes of the natural deposit are described together with methods of enhancing latent fingerprints contaminated with materials such as blood or grease. A variety of optical and physical techniques are also described. Some techniques may be used at crime scenes while others are more appropriately applied in dedicated fingerprint enhancement laboratories to which exhibits are taken. An important aspect of the examination procedure is to minimize interference with the retrieval of other types of forensic evidence