Chapter 6 Powerpoint Flashcards
Why can fingerprints be used for personal identification?
Unique
Persistent
Classifiable
Changes in fingerprints only occur because of
injury
disease
decomposition after death
Friction ridge skin
the skin on the fingertips, palms of hands, soles of feet
characterized by patterns of ridges and furrows (hills and valleys)
Why are fingerprints classifiable?
Arches
Loops
Whorls
Variations and sub categories exist within these three patterns
Fingerprints are:
persistant and unchanging
Fingerprint patterns are formed during:
early embryonic gestation (8-12 weeks)
Genetic composition may:
play a role in determining which patterns develop. but are not totally responsible
Identical twins:
have the same genetic makeup but different fingerprints
Minutiae
features present within patterns of fingerprints
Crucial to fingerprint examination
Individualizing characteristics
Minutiae are formed by ridges:
ending abruptly (ending ridge)
splitting into two ridges (bifurcation)
being short (dot)
These are considered primary minutiae
Nehemiah Grew
First person to study and describe ridges, furrows, and pores on the hand and foot surfaces.
First fingerprint pioneer
Published accurate drawings of finger patterns and palm areas
Made no mention of fingerprint uniqueness
Marcello Malpighi
Researched the functions of the human skin
Observed ridges of palmer surfaces under microscope
Briefly mentioned ridge detail in his publications but did not talk about individuality
Alphonse Bertillon
Devised the first scientific method of criminal identification, Anthropometry
System of bodily measurements for personal identification
11 measurements
Drawbacks: people gain and lose weight, inaccurate measurements taken by officers
Will West v William West
Leavenworth Prison
Will West = new prisoner
Staff member thought he had entered the measurements before
Same measurements fit prisoner William West, already incarcerated
Looked similar
Not related to each other
Juan Vucetich
Police department in Argentina
Value of fingerprints as a means of criminal identification
First recorded case: was murder in 1892
Classification Systems are based on:
ten print fingerprint standards from criminals
Classification Systems are not for:
search individual fingerprints to partial single prints
AFIS
Automated Fingerprint Identification System
Two principal applications for AFIS:
searching files for the presence of a ten print record
searching files for single prints from crime scenes
Why are their different AFISs?
different vendors use different technologies
Different system are usually not compatible with one another
Two Types of AFIS profiles held:
Known files (ten print records)
Unknown files/ Forensic Files (unsolved cases) –> can link cases when same print is submitted to unknown portion from different crimes
FBI Criminal fingerprint database is:
IAFIS: Integrated AFIS
Why would we not find fingerprints at every scene?
gloves worn, wiped or smudged, item was not touched, environment, surface condition, subject
Makeup of fingerprints
- 5% water
1. 5% organic and inorganic materials (amino acids, creatine, fatty acids)
Three Types of finger impressions
latent, patent, plastic
Latent
invisible; made of perspiration and oils; need to be physically or chemically developed to be visible
Patent
visible prints
made in blood, paint, grease, ink, etc.
do not need to be developed to be visualized
may be enhanced using chemical methods
Plastic prints
3D impression
left in soft, pliable surface
chocolate, butter, cheese, wax
creates negative impression
Physical Development Methods for Fingerprints
Cyanoacrylate Ester Fuming (super glue)
Fingerprint powder
Fluorescent powder
magnetic powder
Chemical Development for Fingerprints
Iodine
Ninhydrin
Indandione
Iodine
Reacts with starches, print will be brown in color
use on porous surfaces
affixed using heat
will develop old prints
unstable, must be photographed quickly
Ninhydrin
Reacts with amino acids, print will be purple in color
Can be used after iodine
use on porous surfaces
Indandione
reacts with amino acids
use on porous surfaces
fluoresces with ALS
Dye Stains
Use after CA fuming
Fluorescence examination
Arch
simplest fingerprint pattern
formed ridges that enter on one side and exit on the other
No deltas
Two types: plain and tented
Does not have: looping ridge, upthrust, recurve
Delta
that point on a ridge at or nearest to the point of divergence to two type lines
located at or directly in from of the point of divergence
Core
the approximate center of the pattern
Loop
one or more ridges enter upon either side, recurve, touch, or pass through an imaginary in between delta and core, and pass out upon the same side as they entered
Three basic requirements for a loop
sufficient recurve
one delta
ridge count across as looping ridge
Two types of loops
Ulnar and Radial
Ulnar loop
flow toward the ulna bone (pinky)
radial loop
flow toward the radius bone (thumb)
Whorl minimum requirements
two deltas, recurve in front of each delta
four types of whorls
plain
central pocket
double loop
accidental
Plain whorl
one or more ridges which make a complete circuit
two deltas
at least one recurving ridge within inner pattern when imaginary line is drawn between two deltas
central pocket whorl
similar to a plain whorl
imaginary line drawn from delta to delta must not touch a recurving ridge in front of the inner delta
double loop whorl
consists of two separate loop formations with two separate and distinct sets of shoulders and two deltas
The purpose of an examination is to:
determine the source of a print
exclude the source of a print
ACE - V
Analysis
Comparison
Examination
Verification
Analysis
The assessment of a print as it appears on a substrate
Separate print into its components: substrate, matrix, development medium, distortion, etc.
Establish level of details available
Determine if print is sufficient for comparison purposes
Comparison
Determine whether details in two prints are in agreement based on:
similarity
sequence
spatial relationship
Evaluation
Final determination made for agreement or disagreement of details present in the questioned and known prints
Verification
Independent examination by another examiner
ACE methodology applied
Blind v Non Blind
SWGFAST
Scientific Working Group on Friction Ridge Analysis, Study, and Technology
