chapter `16 Flashcards
biometrics defintion
advanced form of human identification
physiological biometrics
uses physical traits to identify (fingerprints, retina/iris scans, facial scans)
behavioral biometrics
identification through handwriting, voice, keystrokes, gait
gait
how you walk
keystroke
typing pattern
Alphonse Bertillon fingerprints
made 1st systematic personal ID
used anthropometry
most accurate until 20th century
Francis Galton fingerprints
discovered:
anatomy of prints
how to examine and record them
Will West v. William West
changed the way that people were classified and identified. they had the same name, Bertillon measurements, and resemblance to Will West.
showed importance of accurate fingerprint measurements to determine suspects
fingerprints defintion
skin ridges found on the palm-side of thumbs and fingers
3 founding principles of fingerprints
uniqueness
permanent
classified
what determines uniqueness of a fingerprint
ridge characteristics
minutiae
minutiae
individuality determined by ridge characteristics
as many as 150 per finger, no minimum
identity, number, relative location
must demonstrate point-by-point exact comparison for accurate identification
when do fingerprints form?
8th week of development, maybe 12-14
where are prints found on the body?
reproduction on ridges and palms, soles of hands and feet
fingers aid in
gripping
epidermis
outermost layer of skin (not vascular)
dermis
inner layer of skin
dermal papillae
between the epidermis and dermis, where fingerprints are contained
does the dermal papillae contain pores?
yes
3 main fingerprint classifications
loop
whorl
arch
loop
enter from one side, curve, exit the same side
Must have one delta
ulnar loop
opens toward your little finger (usually more common)
radial loop
opens toward your thumb
whorl
minimum of two deltas
plain whorls and central pocket loop
at least one ridge that makes a complete circuit
double loop
two loops combined into one fingerprint
accidental whorl
either contains two or more patterns, or is a pattern not covered by the other categories
4 classifications of whorls
plain whorl
central pocket loop
double loop
accidental
loop classifications
ulnar loop
radial loop
arches
least common
classifications of arches
plain arch
tented arch
plain arch
enters one side, forms a hill, goes out the other side (small wave)
tented arch
comes in from one side, spikes, goes out the other side
Fingerprints are classified based on the presence or absence of
whorls
fingerprint calculation
Whorl on 1st pair finger = 16. 2nd = 8. 3rd = 4. 4th = 2. 5th = 1.
Loops/arches = 0
R index / R thumb + R ring / R middle + L thumb / R little + L middle / L index + L little / L ring
Add numerator + 1 / Add denominator + 1 = your answer
Ace-V
4 step process to identify and individualize a print
ace-v 4 steps
analysis
comparison
evaluation
verification, second examiner double checks
3 levels of comparison
Level 1: general flow and patterns (arches, loops, whorls)
Level 2: locating and comparing ridge characteristics
Level 3: examining pores, creases, and scars
3 results of fingerprint examination
Identification
Exclusion
Inconclusive
AFI’s
automated fingerprint identification system maintained by the FBI
how many images does AFI have
nearly 750 million
how does AFI work
Computer scans and encodes print
Records position and orientation of minutiae
Creates genetic pattern
Stores in database allowing thousands of prints to be compared per second
ranks print to unknown prints
experts compare
takes to court, must have 12 points to match
3 types of fingerprint detection
visible
plastic
latent
visible fingerprint
made when fingers touch a surface after the ridges have been in contact with a colored material
Can be seen
Blood, paint, grease, ink
plastic fingerprint
ridge impressions left on soft materials
Distinct and visible to the eye
Easily located at a crime scene
Putty, wax, soap, dust
latent fingerprint
invisible to the unaided eye
Needs to be developed
Includes the sweat and oils from skin
how are prints identified on nonporous surfaces?
powder
Painted wood, glass, mirrors, plastic, pots, cans, coffee mugs, etc.
how are prints identified on porous surfaces?
chemicals like iodine, ninhydrin, cyanoacrylate (super glue)
Unpainted wood, paper, leather, etc.
iodine fuming
heating iodine crystals, creates a vapor
how to get best results from iodine fuming?
photograph immediately
is iodine fuming permanent?
no, fades
Ninhydrin
reacts with amino acids to produce a purple print
Physical developer
silver nitrate reagent used when other chemical methods are ineffective
Cyanoacrylate
Fumes from the glue adhere to the print to produce a white latent print
Metals, electrical tape, leather, plastic bags
cyanoacrylate is the same as
superglue
cyanoacrylate is only used on _ surfaces
nonporous
superglue fuming process
Add super glue to a tray in a chamber
Add heat source to speed up the reaction
Fumes react with moisture from latent residue
Bonds latent deposit to the surface
how to preserve and transport prints (small object)
photograph
transport without destroying print
how to preserve and transport prints (large object)
developed with powder need to be lifted with tape
