Finger Printing Flashcards
fingerprint
an imprint made by the fiction ridge patterns on the last joint of the finger
friction ridge
one of the corrugated ridges characteristic of the skin of the palmar & plantar surfaces of primates
what kind of finger prints are indistinguishable?
human, chimp, and koala prints
what are finger prints composed of?
- ridges
- grooves
ridge colors on print
black
groove colors on print
grey color
four factors that determines the value of associative evidence
- the specificity or degree of identity of the evidence
- the frequency of occurrence
- the persistence of the transferred material
- the likelihood of alternate explanation
why fingerprints can be used as associative evidence
- uniqueness
- persistence
fingerprint uniqueness
- fingerprints are unique to the individual
- no two people have been observed to have the same fingerprint
do identical twins have the same finger print or forensic genotype?
forensic genotype
fingerprint persistence
fingerprints are persistent morphological features that do not significantly change through time
affect of age on friction ridges
- surface ridges flatten making the appearance less sharp when recovered
- numbers of wrinkles increases
exceptions to fingerprint persistence
- considerable skin damage
- genetic disorders resulting in printless fingerprints
how considerable skin damage can effect finger prints
new scars that are persistent can be used to identified suspects
three categories of finger prints
- latent
- patent
- plastic
latent prints
- invisible to the naked eye
- requires a physical or chemical process to enhance or make prints visible
patent prints
visible prints created when residue, contaminating the finger, are transferred to a hard surface
plastic prints
visible, impressed prints that are made in a soft surface resulting in indentations
details of plastic prints
- less common than patent & latent fingerprints
- relatively easy to locate
- negative prints
common surfaces for plastic fingerprints include
- fresh paint
- putty
- wax
- soap
- grease/oil
- dust
negative print
the resulting finger impression has the opposite features as the associated finger
positive print
- the resulting finger impression has the same features as the associated finger
- elevated residue represents an elevated ridge
broad level comparison (level 1)
- class characteristics
- fingerprint pattern type
3 general fingerprint patterns
- loops
- whorls
- arches
loops
- 65%
- ridge flow enters & exits on the same side
whorls
- 30%
- resembles a bullseye
arches
- 5%
- ridge flow enters & exits on the same side with a wave/rise in the center
most common finger print type?
loops
least common finger print type?
arches
finger print core
the focus of the innermost recurving ridge in a finger print
finger print delta
a meeting point on 3 individual ridge flows
subdivisions of loops
- radial loop
- ulnar loop
subdivisions of whorls
- plain whorl
- central pocket loop whorl
- double loop whorl
- accidental whorl
how to determine whorl type
draw a line between 2 deltas, line cuts across through inner pattern
double loop whorl
2 loops combined into one fingerprint
accidental whorl
contains 2 or more patterns
subdivisions of arches
- plain arch
- tented arch
individual finger print characteristics (minutiae) (level 2)
- the point where a friction ridge begins, terminates, or splits into 2 or more ridges
- comparison involves type of feature & location of feature
level 3 fingerprint details
- edge features: shape & size
- pores: shape, location, & numbers
analytical methods involved in the analysis of evidence
- ACE-V
- analysis, comparison, evaluation, verification
ACE-V: analysis
examiner studies the print to assess quantity & quality of detailed present
ACE-V: comparison
side by side observation of friction ridge detail
ACE-V: evaluation
examiner assess correspondence/non-correspondence & forms a conclusion
ACE-V: verification
independent re-examination by a second examiner using the ACE process
suitability: quality of
- clarity of observed features
- as quality increases, so does the discernibility & reliability of the ridge features
suitability: quantity
- amount of features/area
- number of ridge endings, bifurcations, & dots in contiguous ridges, determined with out any reference to known impressions
sufficiency graph
- in the analysis phase
- the assessment of the impression based on quality & quantity is positioned on the graph to determine its suitability for individualization
sufficiency graph: impressions falls below the solid curve
an individualization is not warranted
sufficiency graph: impressions fall above the solid curve
it may allow individualization
factors affecting the quality & quantity of fingerprint characteristics
- was the surface touched by friction ridges in a suitable manner?
- was there a suitable amount of residue transferred to the surface?
- was the surface suitable to maintain the reside transfer?
- was the environment suitable to receive and maintain the residue?
AFIS - Automated Fingerprint Identification System
- examiner captures the latent print
- latent print is trimmed & enhanced
- examiner plots the minutiae
colors of AFIS
- the red circles indicate ridge endings
- the yellow squares indicate bifurcations
how does the AFIS examiner determine the Y-axis?
- core location
- direction of the print
fingerprint verification
- Quality Assurance protocol
- blind verification
blind verification
the independent examination of one or more friction ridge impressions by another component
