Fingerprints

Forensic Science

Forensic Science

the scientific method of gathering and examining information about the past to use in a court of law (of the forum)

Anthropometry

identification using 11 measurements of extremities

Latent Print

an impression of friction skin usually left unintentionally and requires physical/ chemical processing to be visualized

Patent Print

fingerprint that does NOT require physical/ chemical processing to be visualized; print left in a substance or an impression

Dactylography

study of fingerprints

Galton Details

individualizing characteristics (ending ridges, bifurcations, dots)

Applied Science

scientific process for real life/ practical use

ACE-V

Analysis, Comparison, Evaluation, Verification/ methodology for examining fingerprints

(I)AFIS

(Integrated) Automated Fingerprint Integrated System; 1980s, 1999; used for connections, matches, suspects

NGI

Next Generation Identification (includes biometrics), 2011

LASER

Light Amplification by Stimulated Emission of Radiation

Sublimation

solid to gas, iodine fuming

Polymerization

monomers are bound to form a longer polymer, AFTER superglue fuming

Fluorescence

emission wavelength is longer and lower energy than excitation

Confirmation Bias

focus on proving a decision is correct and could disregard info that doesn’t fit the theory

Contextual Bias

consideration is influenced by background info

Fingerprint History

used for identity, found on pottery

William Hershel

studied the persistence (and uniqueness) of fingerprints by recording his own prints over time

Henry Faulds

method of using ink to record fingerprints, use of fingerprints as a means of individualization

Bertillon

identify people anthropometrically with pics and quant descriptions (11 measurements)

McClaughry

1904, Major who installed the fingerprint system for US gov files to replace anthropometrics (result of William/Will West)

Why won’t twins have the same prints?

They are made after the egg splits and they aren’t based on genetics

Francis Galton

established that prints are unique and persistent (3 main ridge details)

Edward Henry

fingerprint classification system used for filing and retrieval

DeForrest

1902-3, fingerprinting for civil servants and criminals

Identification Division of FBI formed

1924

Purpose of ridges, pores, and creases

friction for a firm grasp and flexibility

Changes over time

width, remodeled papillae, atrophy = flattening

Ridge Aplasia

no epidermal ridges, no prints

Ridge Dysplasia

units not fused, not continuously flowing ridges

Where is friction ridge skin?

Palmar (hands), plantar (feet); no oil glands or hair, more nerve endings

Friction Ridge Skin Layers

epidermis, dermis, hypodermis

Epidermis

outer/ top layer, receptor organ, protective, cell replacement

Dermis

underneath epidermis, root of ridges and furrows (primary surface and secondary under valleys), connective tissue- cells, fibers, blood vessels

Dermal Papillae

in dermis, peg-like projections that create prints, pliable and remodels with age and stress

Papillary System

Eccrine sweat glands with ducts at skin surface and extend through epidermis

Components of Sweat

water, amino acids, enzymes, vitamins, sugars, salt

How are latent prints left?

Sweat leaves pores and covers the finger and ridged area, deposition of sweat with force creates the print

Dermis Components

glands, start of duct, dermis papillae, nerves

Epidermis Components

sweat pores, papillary ridges (fingerprints)

Volar Pads

bumps of tissue under epidermis on surface of hands and feet that affects friction ridge skin development and patterns; exists in a fetus and then recedes in gestation

How are friction ridge skin patterns formed

movement/ recession of volar pads, bumps develop and fuse together, then elevate

What affects pattern and ridges

location and movement of volar pads, time and size of fetus

When do fingerprints start development?

12 weeks

When do fingerprints finish development?

21 weeks

High, round, symmetrical, lower=smaller

Whorls

Asymmetrical pads

Loops

Low and broad volar pads

Arches

Palm Volar Pad Parts

Interdigital, thenar, hyper thenar

Interdigital

between fingers and toes, just beneath the fingers

Thenar

fleshy mass at the base of the thumb

Hyper Thenar

fleshy mass on the palm on the opposite side of the Thenar

Distal Transverse Crease

line of the heart, closest to the fingers, above proximal

Radial Longitudinal Crease

closest to wrist, below proximal and encloses the thenar area and interdistal area, life line

Purpose of identifying fingerprint patterns

use for inclusion and exclusion, used for classification, not individual

Type Lines

lines on either side of delta/ divergence

Shoulders

points where the recurving ridges turn inward or curves, innermost line right before the curve

Core

point where it recurves but on the opposite side from the delta

If two or more possible deltas

choose the one closest to the core

Sufficient recurve

part of a recurving ridge, free of any appendages connecting to another ridge (smooth)

Arches don’t have

deltas (so no core)

Delta

triangulation or a dividing of the ridges

Deltas of whorls

two or more

Counting Ridges

used only for loops, number of ridges between delta and core, not including core or delta

Ulnar Loop

flows in direction of little finger

Radial Loop

flows in direction of thumb, more rare

Loop

ridges enter and exit from the same side with a recurve in the middle (can be right/left slant, radial/ulnar), most common

Loop Requirements

1. sufficient recurve

2. delta

3. ridge count- across a looping ridge

Whorls

2+ deltas, ridges are circular and flow between deltas (only ridges in between deltas)

Types of Whorls

plain, central pocket loop, double loop, accidental

Plain Whorl

inward curve, 1+ ridges make complete circuit

Central Pocket Loop

no lines crossed between delta and core, very tiny whorl, teardrop, at least one ridge makes a complete circuit, no

Double Loop Whorl

two deltas and two separate loop formations and distinct set of shoulders

Accidental Whorl

crazy, 2+ deltas, two different pattern types but no plain arch

Exclusions to Double Looped Whorl

“S”- spoiled- recurves are on the same ridge (loop)

Interlocking- recurve ridges have one end inside the other’s curve

Spoiled

no sufficient recurve in front of a delta (use other delta and go to a loop if a spoiled whorl, go to arch if a spoiled loop)

Arches

ridges enter from one side and exit from the other with a rise in the center, no deltas, rare

Tented Arch

enter from one side, angle/ upthrust in the middle or two of three characteristics of a loop (insufficient recurve)

Whorl Tracing

from left delta to right, trace until at/ above/ below other delta, drop as needed to uninterrupted ridge

Meeting Whorl

1-2 ridges in between end tracing point and delta/ uninterrupted

Inner Whorl

3+ ridges and tracing end is in front of delta (closer to core)

Outer Whorl

3+ ridges and tracing end is below delta (closer to outside)

Classification Parts

Key (#), Major, Primary (#/#), Secondary, Subsecondary, Final (#)

Key

determined by first loop ridge count on right hand

Major

determined by loop ridge count or whorl tracing in thumbs in S (-11), M (12-16), L (17+); I,M,O for whorls

L/L

Primary

based on presence of whorls; first two fingers are 16,16 down to 1,1; plus 1 to num and denom; even #/ odd #

Secondary

based on pattern type in pointers (second column); L/L

Subsecondary

Loop ridge count or whorl tracing in all but thumbs and pinkies;

• Whorl: letter

• Loop: (-9), (-10), (-13): I (low)

• Loop: (10+), (11+), (14+): O (high)

  LLL/LLL

Final

loop ridge count in five (last finger) (or ten if five isn’t loop)

Corner of Finger Block

loop ridge count OR whorl type and tracing

Materials for Recording Fingerprints

printer ink, digital (Livescan), chemically treated paper

Keys for printing

nail to nail, proper amount of ink, first joint

To print a palm

paper around a cylinder

Post-Mortem Prints

fingerprint spoon, powder and lifting tape, remove and print, cast

Print Development on Skin

cyanoacrylate body fuming and magnetic powder (bony, ankle), room temp

Porous Substrates

Paper, raw wood, cardboard

Processing on Porous Substrates

nynhydrin (amino acid)

Non-Porous Substrates

glass, metal, plastic, rubber, painted wood

Processing on Non-Porous

cyanoacrylate fuming, dye stains, powders

Deposition Factors

person’s age, substances prior touched, texture of substrate, surface area, contaminants, pressure, temperature, humidity