Fingerprints Definition: raised portions of skin covered in sweat that when pressed against a surface creates an impression of those friction ridges. (Sweat is a combination of H2O, dirt, and oils.) Unit #3

Unit Objectives At the conclusion of the unit, students will be able to: understand the history of fingerprints; define fingerprints; discuss in detail the method of how fingerprints are created; classify prints according to level I and II; discuss the usages of fingerprints; and discuss the process of AFIS.

Fundamental Rule #1 A fingerprint is an individual characteristic; no two fingerprints have yet been found to possess identical ridge patterns.

Utilization of Fingerprints Identification in pottery and documents. –using either thumb, finger, or palm print.

History of Fingerprints See handout

Fingerprints remain constant through an individual’s life… Why? Fundamental Rule #2 Fingerprints remain constant through an individual’s life… Why?

Formation and Anatomy How do fingerprints form? http://physicsworld.com/cws/article/news/2004/oct/11/fingerprint-model-makes-an-impression FPs are formed during the 10th week of gestation at the stratum Germinativium (basal) (5th and lowest layer)

Volar Pads-opposing side of fingernails Volar Pads-opposing side of fingernails. When volar pads shrink, FP’s begin to form. Ridges are created perpendicular to the direction of stress. Volar pad structure leads to specific class: round -> whorls flatter -> arches

Henry Classification Characteristics are named after general appearances Three levels of classification Level I – General Categories Level II – Friction Ridge Minutiae Level III – Unclassifiable features

Fundamental Rule #3 Fingerprints have general pattern classifications such as arch, loop, and/or whorl that allow for identification.

Deltas and Cores

Level I: Pattern Classification Loops Percentage of population Bases of Categories

Level I: Pattern Classification Arches Definition: have friction ridges entering on one side, rises in the center and exits in the opposite direction of entry Percentages

Level I: Pattern Classification Whorls Definition: pattern with two deltas causing the ridges to swirl around a center Categories of Whorls

Level II – Friction Ridge Minutiae Small individual markings within a Level I print. Ten FR minutiae that help fingerprint examiners compare unknown prints to known.

Bifurcation Bridge FR diverges from one ridge to two continuous ridges FR connects two adjacent FR

Core Delta The very center FR of either a ____ or ____ A triangular structure that causes other FR to change direction

Crossover Dot Two FR intersect to form a chromosomal- like structure A very short and wide FR located between two adjacent FR

Double Bifurcation Enclosure Eye One FR diverges twice resulting in three FR Enclosure One FR diverges, creates an opening, and then re-enters into the same FR Eye An enclosure with a dot

Hook On FR diverges into two FR resulting in one continuous ridge and one short ridge Short Ridge A short FR that is discontinuous

Island Ridge Ending A ridge between two adjacent FR The Termination of a FR

Triple Bifurcation Specialty The divergence of one FR into four continuous ridges Specialty A unique minutiae pattern that cannot be categorized

Level III Classification Pore identification

Types of Crime Scene Prints 3 categories Plastic or Indented 3D fingertip impressions in a soft substance Mediums: wax, putty, clay or drying paint

Patent Visible prints to the naked eye Medium: bloody FP on a countertop

Latent Invisible FP requiring techniques of recovery Most common type

Prints are divided into two subcategories Porous Non-porous

Search Techniques for CS Prints Technique is dependent on? What is the order to look for prints? Factors Affecting Visibility Surface Physical condition of print owner Lighting angles Heat Duration from print to discovery

Factors Affecting Duration of Prints Remaining: Weather Air Currents Humidity Quality of Prints Affected By: Finger contact Pressure

Type of Print and Surface Powdering Type of powders used Instrumentation for powder application Types of powders Lifting Techniques

Chemical Processing Location? Crime Scene or Laboratory? Chemicals react with minerals and organic matter of the print Perspiration

Types of Chemical Techniques Physical Development Small Particle Reagents Used on: paper, cardboard, new, rusty, and galvanized metal, bricks, rocks, concrete, plastic, vinyl Chemical Development Ninhydrin Reacts with? Iodine Fuming Reacts with? Cyanoacrylate Fuming Reacts with?

ACE-V Analysis Comparison Evaluation Verification

Analysis and Identification Comparison and recognizing of difference between the minutiae of known and unknown prints Focus on 3 different levels of details Level I Level II Level III

AFIS Automated Fingerprint Identification System Searches for prints…does not ID them 1980 Process Cons to AFIS Prints of poor quality can cause examiner to guess on the pattern classification Poor prints can also lead to a large number of candidates Three levels of AFIS

IAFIS Integrated AFIS FBI data base Largest biometric database in the world Data includes: mug shots, scars and tattoos, height and weight, aliases 27 minutes to 2.5 hours to process