Fingerprints Flashcards
1882 - Alphonse Bertillion, French anthropologist, devised method of body
___measurements__ to produce a formula used to classify individuals.
Bertillion’s __formula_ involved taking the
measurements of a persons body parts, and recording these __measurements__on a card.
what happened in the will west case?
Will West sent to Leavenworth, KS in 1903 and his measurements and picture were taken. It was determined that he was already in prison!
William West was already in prison for murder. Their measurements were the same.
what is dermatoglyphics?
The study of patterns of dermal ridges present on fingers, palms, toes, and soles
? ridge patterns
friction
hills are called ?
valleys are called ?
ridges
furrows
what are dermal papillae?
are upward extensions of the dermis into the epidermis forming the ridge pattern the fingerprint
they continue to regenerate, therefore the ridges maintain permanent
2 different layers of friction ridge skin
-epidermis
-dermis
characteristics of epidermis
-outermost layer
-protection
-skins that are shed
characteristics of dermis
-innermost layer
-protection of internal organs
-nutrient exchange
Fingerprints can be used as a means of identification because of two characteristics:
-permanence: remaining unchanged indefinitely
-uniqueness
fingerprints are one of the oldest ?
fingerprint disciplines
friction ridges are formed early in ?
embryonic development (4th fetal month)
friction ridges ? change
NEVER
Families may possess ? characteristics
class
-papillae arrangement is genetically based
when can friction ridges change?
-except to amputations, mutilation, scars
-growth will only change relative size of fingerprint
Maternal environment will?
determine the final arrangement of the ridges
identical twins ? have identical fingerprints
DO NOT
-only identical DNA
While the baby is developing within the womb, the baby is moving around, touching things, etc. And this will determine what?
the final ridges
3 types of fingerprints
-Latent
-Patent
-Plastic/3D
what are latent prints?
made when a person leaves the oil, water, salt (perspiration) from their hands onto another object
- typically invisible to the naked eye
- need black powder to make visible
what are patent prints?
-visible
made when a print is contaminated with a foreign substance and is deposited onto another object
- example: blood, paint, ink, food
what are plastic/3D prints?
made when a print is left in a malleable material
- example: clay, chocolate, wax, gum
3 types of fingerprint classifications
-loops
-whorls
-arches
characteristic of loops and 2 types
65% of population
1. ulnar
2. radial
characteristic and classes of whorls
30% of population
1. plain
2. central pocket loop
3. double loop
4. accidental
characteristic of arches and 2 types
5% of population
1. plain
2. tented
what is the core?
the center of the pattern
what is the delta?
the area of the pattern where there is a triangulation or dividing of the ridges
which type of fingerprint classification has a delta and a core?
loops
which type of fingerprint classification has at least 2 deltas?
whorls
which type of fingerprint classification has no delta or core?
arches
individual characteristics of fingerprints
points of minutiae
what does it mean to be unique?
ridge details within fingerprint patterns that make it possible to compare and individualize prints
average amount of minutiae on a given print
75 individual minutiae
comparing unknown to known samples
More minutiae in common, the better
Research suggests 8-16
No set standard
types of minutiae
-ridge ending
-spur
crossover
-short ridge
-lake
-ridge dot
-bifurication
detection of fingerprints
oblique lighting for initial search
Enhance with fingerprint powder OR
Enhance with chemical
what is oblique lighting? another word for it?
Oblique lighting/ skim lighting: holding flashlight at 40 degree angle
Type of fingerprint powder and brushes
Traditional Black Powder- fiberglass brush
Application: Dip, Tap, Twirl
__Magnetic__ Powder- magnetic wand “Magna Brush”
__Fluorescent_ Powder- feather brush, requires ALS
how are the powders used?
Used on non-porous surfaces
Lift with tape/photograph
Be gentle and don’t over-powder
pro tip on magnetic powder
tiny pieces of magnet in it, pull plunger on top of brush and pour powder back into jar and pick up filament of extra black powder from fingerprint
13 most common types of chemical enhancers
Amido Black
Coomassie Blue
Cyanoacrylate
DFO
Dye Stains
Gentian Violet
Iodine Fuming
LCV
Ninhydrin
Physical Developer
Small Particle Reagent
Sticky Side Powder
Sudan Black
Blood stain reagents
stain reacts with proteins in blood
turns blue-black color
what are the techniques used for bloody fingerprints?
Amido Black
Coomassie Blue (to enhance)
Leuco-Crystal Violet (LCV)
Used for comparison photo with enhancer
cyanoacrylate (superglue fuming)
used on non-porous surfaces (no small holes)
creates visible white prints
Preserves print and makes it semi-_permanent_
Can potentially be dusted and lifted numerous times
Can also be used on __deceased_ persons
what happens after creating visible white prints
- can then be dusted or dyed
- photographed and/or lifted
types of dye stains
RAM, MBD, M-Star, Ardrox, Nile Red, Basic Yellow, Rhodamine 6G, etc.
how does the dye stain work?
Adheres to super glued prints: First superglue print then dye on it
Analyzed under alternate light source, print will fluoresce, must photograph
What is small particle regaent (SPR)?
Reagent is powder suspended in water and detergent
how does SPR develop fingerprints?
Develops fingerprints on Wet and __metal_ non-porous surfaces
NO POROUS SURFACES
Adheres to lipids in fingerprints and develops a grey colored print
characteristics of Gentian Violet (crystal violet)
Stains __Fatty________components of latent prints
Used on the ____sticky_________side of tape
Turns prints purple
characteristics of sticky side powder (wet wop)
Black powder in solution
Used for retrieving fingerprints on _tape______
Adheres to fingerprint ___residues__________ and turns prints black
Process can be repeated numerous times
what can sticky side powder be used after?
cyanoacrylate
characteristics of ninhydrin?
Used on ___porous_________ surfaces
Reacts with ___amino acids____________ in fingerprints to form a purple colored compound
Popular because it is easy to use
Can apply by spray, swab, or dunk
what is it called when the purple compound forms in reaction with amino acids in fingerprints?
- Called Ruhemann’s Purple
with ninhydrin, prints will usually appear ? but may take ?
within hours
up to 10 days for weaker prints
how to speed up the reaction for ninhydrin?
humidity/temp
ninhydrin is used last if also processing with what?
with DFO or Iodine, not good on wet items
characteristics of iodine fuming
Good on __porous________ and non-porous surfaces
Heat iodine crystals to form iodine gas
Gas adheres to fingerprint as a yellow/brown color
what are cons with iodine fuming?
-Vapors are toxic
>causes cancer
-Interferes with using other ___techniques___
-Temporary, so must __photographs to preserve
>print begins to disappear as reaction ends
characteristics of diazaflouren (DFO)
Used on __porous__ surfaces
Can use in conjunction with __Ninhydrin___________, but must use DFO first
Must use _ALS__ to view print
DFO reacts with amino acids ?
to give a highly fluorescent red colored product
DFO can use in conjunction with ?
__Ninhydrin_, but must use DFO first
characteristics of physical developer
silver-nitrate based solution
Used on __porous_ surfaces that are wet or have been wet
>especially good on paper bags and currency
>has tendency to develop older prints
Must photograph to preserve prints
Cumbersome and multiple step procedure
>very effective on currency but tedious
physical developer reacts with sweat components in the fingerprints to create ?
grey or almost black color
physical developer can use after ?
ninhydrin or iodine
characteristics of sudan black
Used on non-porous substrates
Reacts with _lipids________ and will stain the print blue-black
Messy
sudan black is good for what type of substrates?
oily and greasy substrates
what can’t sudan black be used on?
cannot use on dark colored substrates
characteristics of fingerprints of children
fragile
will dissipate in a short time
minimize powder used
how long will a fingerprint last for a child vs adult?
4-6 hours
days to weeks
characteristics of fingerprints of human skin
Can retrieve on living or deceased persons
Fingerprints may last up to 1.5 hours on living person
Don’t put body in ___fridge_________
why shouldn’t you put a body in the fridge?
it will form condensation on skin, no more prints
can use super glue on part of body then use powder to dust
what is dead man’s spoon?
Use _curved__________ fingerprint card strip holder
aka “dead man’s spoon”
Fingerprint card cut into two strips which fit into spoon slots
Finger pressed into __curved__________ spoon to obtain print
how to take prints of dehydrated fingerprints?
Tie off finger just below ___first_______ joint with twine
Inject fluid (saline solution) with needle under skin to “plump” flesh
Then use dean man’s spoon technique to take fingerprints
what are putrefied fingerprints?
Secure peeled skin of deceased ‘_skin glove’
Slide peeled glove over own gloved hand and roll
a newer way to get fingerprints? why is it good?
-live scan
-If you don’t get a good print, the computer will tell you to do it again
-Will know if it is a good and classifiable print the same day vs back in the day would have to re-roll prints
-don’t need ink, very clean very demure
what does AFIT stand for?
Advanced Fingerprint_Identification_ Technology
what does AFIT do?
Converts images of fingerprints to __digital_ minutiae
>records relative position and orientation
Different requirements from state to state
List of possible __matches__ are retrieved
Examiner must __visually_ compare
how is AFIT not like CSI?
Renders back POSSIBLE matches (~COULD BE 300), not a 100% match
Doesn’t need to go further down the list once a match is made
what is AFIT formerly known as?
AFIS 2010
AFIT is the new fingerprint-matching algorithm improved matching accuracy from
92 percent to more than 99.6 percent
how is AFIT effective according to contributors?
Contributors experienced faster response times, fewer transaction rejects, and increased frequency of identification
what does IAFIS stand for?
Integrated Automated Fingerprint Identification System
>National Database
when did the FBI implement the IAFIS?
1991
More ? million sets of criminal subjects and ? million of civil subjects in database
70, 31
How is the search algorithm very advanced?
can search millions of prints in ~27 minutes
must still verify match by human
must be qualified as expert to testify in court
