Which type of fingerprint evidence cannot be seen with the naked eye?

Latent fingerprint evidence refers to prints that are not visible to the naked eye and require special techniques to be made visible, such as dusting with powders or using chemical reagents. This type of evidence is typically left behind on surfaces when the oils and sweat from a person's skin transfer to that surface, forming a fingerprint that can be revealed through various means.

The other types of fingerprint evidence include plastic fingerprints, which are three-dimensional impressions made in materials such as wax or clay, and patent fingerprints, which are visible prints left on a surface by substances like ink or blood. Impression evidence can cover a broader category of marks and may include both visible and non-visible prints. However, the defining characteristic of latent fingerprints is that they are not immediately observable without enhancement techniques. This highlights the unique nature of latent fingerprints in the context of fingerprint evidence and forensic investigations.