ABSTRACT
Because fingerprints are unique, they are used to identify people. In forensic science, we think of fingerprints as being used primarily to help locate, identify, and eliminate suspects in criminal cases. But fingerprints, along with DNA (Chapter 9), and dental remains, are also important in making unequivocal identifications of human remains when more conventional methods of postmortem identification cannot be used. Fingerprints may be thought of as one member of a class of biometric identifiers that would also include retina or iris patterns, face thermography, and some others. As the technology for rapid scanning and storage of these biometric patterns develops, they are becoming more important as security features to help avoid problems associated with forged identification documents. The two features of
fingerprints most important for their use as a means of personal identification are that (1) every fingerprint is unique (to an individual), and (2) fingerprints do not change during a lifetime (unless there is damage to the dermal skin layer). (For a discussion of career preparation for this field, see Sidebar 13.1.)
It has long been recognized that the fingers, palms of the hands, and soles of the feet of humans (and some other primates) bear friction ridge skin. These areas are characterized by a complicated pattern of hills and valleys. The hills are called ridges, and the valleys are called furrows. On the end joint of the fingers a number of basic patterns are formed by the friction ridge skin. Within each basic pattern are numerous possible variations. The patterns form on these skin surfaces early in embryonic development and remain constant throughout embryonic life, birth, and the life of the individual. An individual’s genetic make-up probably plays a part in determining the sizes and basic shapes of the patterns and ridges, but it is not the only factor. We know this because identical twins, who come from the same fertilized egg and thus have identical genetic make-up, have different and distinguishable fingerprints.
