ABSTRACT
Latent prints are invisible, and thus require processing with fingerprint powders and/or chemical reagents to make them visible. The quality of prints developed is variable and depends on the texture and permeability of the substrate; the quantity of material deposited; the composition and age of the latent print; environmental effects; distortion; and the methods of development, documentation, and collection. When latent prints are placed on porous substrates, the eccrine deposits are absorbed by the substrate, while latent prints placed on nonporous substrates remain on the surface. Semiporous items have properties of both porous and nonporous substrates. Specific chemical reagents and physical processing methods are utilized in a particular processing sequence on each type of substrate. Regardless of the processing method used, safety and awareness of laboratory hazards are paramount. If DNA testing will be requested, certain processes are not recommended as they degrade DNA.
