Chapter 19 Fingerprints (1)

Friction Ridge Examination Overview

  • Friction ridge examination is a critical method for individualization in forensic science.

  • Fingerprint identification remains the current leader in identification markers despite recent court challenges to its scientific basis.

Historical Background

Early Theories of Criminality

  • Lombroso's theory suggested that criminals had distinct physical traits (e.g., large jaws, low foreheads).

  • This sparked interest in identifying measurable traits for identifying criminals.

Bertillion System

  • Bertillion developed Bertillionage, a system of anthropometric measurements.

  • It was complex and challenging to standardize.

Development of Fingerprint Identification in the U.S.

  • 1902: First systematic fingerprint identification in the U.S. in NYC during a scandal.

  • 1904: Following this, a fingerprint bureau was established in Leavenworth Prison.

  • 1915: Formation of the International Association for Identification.

  • 1924: FBI established an Identification Division for fingerprint records.

Understanding Friction Ridges

Definition and Formation

  • Friction ridges are patterns found on the digits and palms of primates.

  • Begin forming in fetal development (9-10 weeks) and solidify by 24 weeks.

Factors Affecting Ridges

  • Genetic and environmental factors, as well as trauma, can alter ridge patterns.

Types of Friction Ridge Prints

Patent Prints

  • Visible without assistance and occur due to transfer of materials.

Latent Prints

  • Require assistance to visualize, typically made visible with fingerprint powders or chemical methods.

Collection Techniques

  • Fingerprint powders create contrast for visualization.

  • Specific dyes and chemicals are used depending on the surface type (e.g., Amido black for blood).

Principles of Analysis

Minutiae Analysis

  • Unique patterns depend on the kind, number, and arrangement of ridge features (minutiae).

  • Prints must be fully compared to determine identity.

  • Point counting standards vary (between 8 and 20 points).

Classification of Fingerprints

Major Patterns

  • Loops: 60-65% prevalence in fingerprints.

    • Ulnar/ Radial based on flow direction.

  • Arches: Rare, with defined entry and exit patterns.

  • Whorls: 30-35% prevalence; subdivided into types.

Modern Techniques and Systems

Automated Fingerprint Identification Systems (AFIS)

  • AFIS enables capturing, storing, and searching fingerprints.

  • IAFIS enhances the sharing of criminal fingerprint data.

Final Examination Standards

  • Identification requires sufficient detail across Levels 1, 2, and 3.

  • Overall quality and comparison of minutiae are essential for conclusive identification.

Conclusion

  • Despite controversies and challenges, friction ridge examination remains a cornerstone of forensic science.