Fingerprints can be found on any solid surface including human body. Fingerprints are categorized into three according to the type of surpafces which they are found and if they are visible or not
1. Impressed prints - Three-dimensional prints found on soft surfaces (e.g., soap, wax, wet paint, etc.)
2. Patent prints - visible prints formed when blood, paint, ink, etc. is transferred from a finger to a surface, and;
3. Latent prints - formed when the body’s natural oils and sweats on the skin is redeposited onto another surface.
How are fingerprints collected?
However, fingerprint powders could contaminate the evidences and ruin the examination of other prints. This is the reason why an alternate light source is used or cyanoacrylate is applied before using powders.
This process can be performed before applying powders or dye stains, usually performed on nonporous surfaces and exposing them to cyanoacrylate vapors.
Impressed prints are those that were made in soft materials or tissues by pressing down with fingers or hands, which can be photographed or casted with molds if possible.