Forensics Chapter 6 Flashcards

Fingerprints Overview

• Fingerprints result from the combination of oil and skin secretions mingling with dirt.
• They serve as individual evidence rather than class evidence, making them unique to each person.

Fingerprint Collection Techniques

• Always photograph a fingerprint prior to attempting to lift it.
• Full prints are not necessary for comparison with crime scene fingerprints.
• Plastic prints (three-dimensional) do not require dusting or treatment for identification.

Fingerprint Formation

• Fingerprints begin to form at around 10 weeks of gestation, influenced by skin cell growth in the fetus.
• Fingerprints consist of ridge patterns distinct to each individual.

Types of Fingerprints

• Patent fingerprints are visible prints left by fingers coated in substances like blood or ink.
• Latent fingerprints are hidden prints made visible using powders or chemicals.
• Plastic fingerprints are impressions in soft materials such as clay or putty.

IAFIS and Fingerprint Technology

• The Integrated Automated Fingerprint Identification System (IAFIS) enhances fingerprint search efficiency by electronically accessing databases from various agencies.
• Current fingerprint identification technology can be prone to human error due to reliance on manual input and analysis.

Fingerprint Analysis Components

• The presence of two deltas in a fingerprint indicates a whorl pattern.
• Ridge count is determined by counting the ridges between the delta and the core.
• Specific components in fingerprints chemically react with various substances for analysis:
  • Ninhydrin reacts with amino acids.
  • Cyanoacrylate also reacts with amino acids.
  • Silver nitrate reacts with chloride from perspiration.
  • Iodine fuming reacts with carbohydrates in latent prints.

Fingerprint Patterns and Characteristics

• Fingerprints are categorized into three primary patterns: arches, loops, and whorls.
• The minutiae of fingerprints include unique ridge details such as shapes and positions, contributing to their individuality.
• A core is the center point found in loop and whorl patterns.
• Deltas are triangular ridge formations that diverge at a distinct angle.

Alteration of Fingerprints

• Fingerprints can be altered through methods such as applying acid, surgical removal, or inverting them surgically.

Additional Fingerprint Terminology

• A ten card is a form used for recording and preserving a person’s fingerprints.
• Ridge patterns are formed by recognizable configurations at the end joints of fingers, critical for fingerprint analysis.

Test your knowledge on Chapter 6 of Forensics with these flashcards. This quiz covers key concepts related to fingerprints and their significance in forensic evidence. It's a great way to reinforce your understanding of individual versus class evidence.