But it wasn't until the late 1800s that fingerprints were used as evidence to link a suspect to a crime. These ridges allow people to pick up and handle objects easily. Each person, even an identical twin, has a totally unique pattern of ridges on his or her hands and feet. And for each person, the pattern on each finger or toe is unique and different from the pattern on every other finger or toe. A fingerprint is an impression of these ridge patterns transferred to a surface.
Fingerprints occur because glands in our hands and feet secret liquids, mainly sweat and oils.
These liquids leave the patterned mark of our fingerprints on almost everything we touch. There are three ways that fingerprints are valuable as evidence. First, fingerprints can confirm the identity of a person. When a criminal is taken into custody, it is a fairly simple task to take his or her fingerprints and crosscheck them against other prints. This will prove who the criminal is and determine whether he or she has a criminal record or whether the police wants him or her.