Forensic Science: Fingerprint Identification
Scientific Basis & Legal Application
Fingerprint identification remains the gold standard in forensic identification because friction ridge skin is both unique and permanent.
1. Principles of Friction Ridge Analysis
- Formation: Ridges are formed between the 3rd and 4th month of intrauterine life.
- Permanence: They remain static until decomposition after death.
- Individuality: Even identical twins have different fingerprints.
2. Classification: The Henry System
| Pattern | Details |
|---|---|
| Arches | Plain or Tented; no deltas. (Rarest) |
| Loops | Radial or Ulnar; one delta. (Most common) |
| Whorls | Plain, Central Pocket, Double Loop, Accidental; at least two deltas. |
3. NEET PG High-Yield Pearls
- Minutiae Points: These are the ridge endings, bifurcations, dots, and enclosures. Legal identification typically requires 8–16 points of comparison.
- Development of Latent Prints:
- Iodine Fuming: For porous surfaces (paper).
- Powder Dusting: For non-porous surfaces (glass/metal).
- Ninhydrin: Reacts with amino acids (sweat) on paper.
- Cyanoacrylate (Superglue) Fuming: Best for hard surfaces.
- Comparison Studies:
- Poroscopy: Studying the number/shape of sweat pores.
- Edgeoscopy: Studying the physical contours of the friction ridges.
- Adermatoglyphia: A rare genetic condition characterized by the total absence of fingerprints.