Transcript fingerprints

FINGERPRINTS
CHAP. 14
http://investigation.discovery.com/videotopics/forensics/videos/inside-the-csi-labfingerprints.htm
History of Fingerprinting





1883 Bertillon System
Portrait Parle- verbal eyewitness description,
physical characteristics, dress
Photographs
Anthropometry- skeleton does not change
after 20 y.o., 11 body measurements (height,
reach, head width, left foot length)
Used for ~ 20 years
History of Fingerprinting



Chinese used fingerprints to sign legal
documents 3000 years ago
1800’s William Herschel required Indian
natives to “sign” contracts with hand imprint
1880 Henry Fauld published the importance
of fingerprints for identification (thief
confesses when fingerprints compared)
History of Fingerprinting







1892 Francis Galton publishes Finger Prints
Anatomy of FP
Methods for identifying and recording
Three patterns (loops, arches, whorls)
No two prints alike *(calculations 64 billion)
FP stay the same
British government adopts system as
supplement to the Bertillon system
History of Fingerprinting




1891 Dr. Juan Vucetich devises workable
classification system
1897 Sir Edward Henry’s classification
system adopted by Scotland Yard in 1901
Similar version used in United States
1903 Fingerprints distinguished prisoners
with same Bertillion measurements (Will
West/ William West)
History of Fingerprinting- US





1901 New York City Civil Service Commission first
official system in US (civil service applications)
1904 Scotland Yard reps train police officers in FP
identification at St. Louis World’s Fair
1924 FBI merges records (Bureau of Investigation
and Leavenworth)
WWI FP’s used throughout Europe
1999 US vs. Byron C. Mitchell- FP admissibility
upheld- “human friction ridges and human friction
ridge skin arrangements are unique and permanent”
Fundamental Principles of Fingerprints
Three Principles



First principle: A fingerprint is an individual
characteristic
Second principle: A fingerprint will remain
unchanged during an individual’s lifetime
Third principle: Fingerprints have general
ridge patterns that permit them to be
systematically classified
First principle: A fingerprint is an
individual characteristic





No two fingers have yet been found to possess
identical ridge characteristics
Individuality determined by minutiae/ridge
characteristics
Individuality-Identity, number and location
Ridge endings, bifurcations, enclosures,
islands, ridge crossing, short ridge
~150 ridge characteristics per print
First Principle- Judicial Proceeding







FP comparison- Identical characteristics in same
location
Point-by-point comparison by expert
Comparison charts (pg. 409)
Usually partials at scene
1973 International Association for Identification“no valid basis exists for requiring a predetermined
minimum number of friction ridge characters which
must be present to establish positive identification
Usually 8-16 (~12)
Final determination based on experience and
knowledge
Fingerprint Comparison
Second principle: A fingerprint will remain
unchanged during an individual's lifetime




Friction Skin provide for firmer grasp and
resistance to slippage on the fingers and
thumb (palms, soles)
Ridges (hills) and Grooves (valleys)
Determined by dermal papillae
Formed during fetal development
Second Principle






Sweat gland pores in ridges
Perspiration and oils (from hairy parts of
body) transferred to surface leaving
fingerprint
Can’t change but maybe obscure
Scarring down to dermis
John Dillinger tried to obliterate prints with
acid (pg. 412)
http://investigation.discovery.com/videos/ialmost-got-away-with-it-a-man-withoutfingerprints.html
Third Principle: Fingerprints have general ridge
patterns that permit them to be systematically
classified

Three classes: Loops, whorls, arches
Fingerprint Patterns- LOOP






Most common, 60-65%
Ridge lines enter from one side of
pattern,curve around and exit from same side
Radial or Ulnar Loop
Two Type Lines
One Delta
Core (“center”)
LOOP
Fingerprint Patterns- Whorl (4)





30-35%
Ridge patterns are rounded or circular
Type Lines
At least two deltas
Plain, Central Pocket Loop,
Double loop, Accidental
WHORL

Plain Whorl, Central Pocket
At least one ridge makes a complete circle
(spiral, oval)
Plain- Line between 2 deltas touches circle
Central Pocket- Line does not touch circle

Double Loop- Two loops

Accidental- Combination of patterns
Fingerprint Patterns- Arch




Least Common (~5%)
Plain Arches, Tented Arches
Ridge lines enter from one side, rise to center
(sharp rise in tented) and exit other side
No type lines, deltas or cores
ARCHES

Plain Arch

Tented Arch
Classification of Fingerprints





FBI System- Primary Classification- 1st step
Based on Henry’s Ten finger system
All cards divided into 1,024 Groups
Need full set of prints
Doesn’t identify, narrows down
Primary Classification








Fingers paired up
RI RR LT LM LL
RT RM RL
LI
LR
Whorl pattern on 1st pair-16
2nd pair = 8
3rd pair = 4
4th pair = 2
5th pair = 1
Arch or loop = 0
Primary Classification



Values totaled and 1 added to both numerator
and denominator
Example: (RI and RM are whorls)
16 + 0 + 0 + 0 + 0 + 1 17
0+ 8+0+0+0+1 9
~ 25% are in 1/1 category (all fingers are
loops or arches)
Automated Fingerprint Identification
Systems (AFIS)






Automatic scanning devices convert FP image to
digital minutiae showing ridge endings and
bifurcation
Stores and retrieves FP record
Thousands of comparisons in seconds
Produces list of file prints w/ closest correlation
National Institute of Standards and Technology
exchange of data between AFIS systems
Final verification by FP expert
AFIS
Kinds of Fingerprints



Visible- are visible!!, print left by material
transferred from finger to surface (blood, ink,
paint, grease)
Plastic (physical)- impression left on soft
surface (putty, soap, wax, caulking, dust)
Latent- not visible to naked eye, perspiration
and/or oil transferred to surface
Detecting Fingerprints



Depends on surface:
Nonabsorbent Surfaces- hard, solid (Exglass, mirror, tile, painted wood)
Porous Surfaces- soft, low density (paper,
cardboard, cloth)
Detecting Fingerprints- RUVIS




Reflected Ultraviolet Imaging System
Locate prints on nonabsorbent surfaces
No chemicals or powders
UV light  print  reflected back  UV
converted to visible light by image intensifier
RUVIS
Latent Print on Duct Tape
Latent Print on Painted Wall
Nonabsorbent Surfaces-Powders





Apply w/ camel’s hair or fiberglass brush
Aluminum dust (dark-colored surfaces)
Black carbon or charcoal (light-colored)
Magnetic-sensitive powders (textured)
applied with Magna Brush
Fluorescent powders visible w/ UV lightprovide for obvious contrast
Powders
Nonporous Surfaces- Super Glue





Cyanoacrylate Fumigation
Metals, leather, electrical tape, plastic bags
Textured surfaces
Chamber
Produces white-appearing print
Super Glue Fumigation
Porous Surfaces- Chemical
Treatments



Iodine Fumigation- temporary, must photograph,
iodine crystals sublimate to vapor
Iodine + Na or Oils = Print (brown)
Fix w/starch solution (blue)- visible for weeks/
months
Ninhydrin- reacts w/amino acids (protein) in sweat,
aerosol spray, turns purple-blue color, 1-48 hours
Physical Developer- silver nitrate based liquid,
wet  dry articles, washes away proteins
Iodine Fumigation
Ninhydrin
Physical Developer
Laser


Latent prints fluoresce (absorbs and reemits
light in longer wavelengths) when exposed to
laser light (argon ion)
Chemicals induce fluorescence and increase
sensitivity of detectionZnCl after ninhydrin
Rhodamine 6G after Super Glue
ALS






Alternate Light Source – High Intensity
Quartz halogen, xenon arc, indium arc
Focused through fiber optic cable
Passed through filter to select wavelength
Portable
As effective and cheaper than laser
New Chemical Treatments

DFO ( 1,8-diazafluoren-9-one)- 2.5 times
more effective than ninhydrin, porous
surfaces, ALS

RAM, RAY, MRM 10 (Dye Combinations)
w/Super glue cause fluorescence
Lifting and Preserving Fingerprints





Photograph (1:1) and overall
Transport evidence to lab, if possible
Preserve DNA
Powders lift w/adhesive tape, lifting cards
Digital Imaging- picture converted to digital file
composed of pixels, enhanced (spatial filtering and
frequency Fourier transform (FFT), manipulated,
enlarged, color elimination and isolation,
simultaneous comparison
Obtaining Fingerprints






Fingers should be clean and dry (alcohol)
Individual to right and rear of taker, forearms length
from fingerprinting device, ~ 39 inches high
Finger should be rolled over ink (thumb toward
center, fingers away from center), Tuck other fingers
under
Ink should cover nail to nail, down to joint
Rolled- Individual impression is rolled nail to nail
Plain- All fingers at once, then thumb