Fingerprint Fundamentals
Fingerprints are formed during fetal development (around 10-16 weeks) when the friction ridge skin of fingers, palms, and soles develops unique patterns influenced by genetics and random prenatal conditions. Three fundamental principles underpin fingerprint identification: every fingerprint is unique (even identical twins have different prints), fingerprints remain unchanged throughout life (barring deep scarring), and fingerprints fall into classifiable patterns. The three primary pattern types are loops (60-65% of all prints—ridges enter and exit from the same side), whorls (30-35%—ridges form circular or spiral patterns), and arches (5%—ridges flow from one side to the other with no recurve). These patterns enable systematic classification in databases like the FBI's Integrated Automated Fingerprint Identification System (IAFIS), containing over 150 million sets of prints.