Transcript Fingerprinting - cloudfront.net

FORENSIC SCIENCE
FINGERPRINTING
Courtesy of C. Fanning
Crystal Violet
Courtesy of C. Fanning
Courtesy of C. Fanning
Red Fluorescent
Inked
15-1
HISTORY OF FINGERPRINTING
•The first systematic attempt at personal identification was
devised by a French police expert, Alphonse Bertillion.
•The Bertillion system relied on a detailed description of
the subject, combined with full length and profile
photographs and a system of precise body measurements
called anthropometry.
•In 1880 Henry Fauld used fingerprints to identify a criminal
•In 1892 Francis Galton published his classic textbook
Finger Prints. At Galton’s insistence, the British
government adopted fingerprinting as a supplement to the
Bertillion system.
•The next step was the creation of classification systems
capable of filing many thousands of prints in a logical and
searchable sequence.
15-2
FRANCIS GALTON (1822-1911)
“Father of Fingerprinting”
Developed fingerprinting as a way to uniquely
identify individuals.
HISTORY OF FINGERPRINTING
•Sir Edmund Henry 1896 created the modern system of a
ten card fingerprint record that was based upon the patters
of “arch”, “whorl”, or “loop”.
•In 1903, when the Bertillion system could not distinguish
between two men in a criminal case (one Will West and the
other William West), it was fingerprinting that clearly
distinguished them.
•After the Will West incident, the use of fingerprinting by
the New York City Civil Service Commission in 1901, and
the training of American police by Scotland Yard
representatives at the 1904 World’s Fair, fingerprinting
began to be used in earnest in all major U.S. cities.
15-4
FINGERPRINT PRINCIPLES
•Fingerprints are a reproduction of friction skin ridges
found on the palm side of the fingers and thumbs.
•The basic principles underlying the use of fingerprints in
criminal investigations are that:
1. A fingerprint is an individual characteristic
because no two fingers have yet been found to
possess identical ridge characteristics
2. A fingerprint will remain unchanged during an
individual’s lifetime; and
3. Fingerprints have general ridge patterns that
permit them to be systematically classified.
•Mathematically, the probability for the existence of two
identical fingerprint patterns in the world’s population is
extremely small. Besides theoretical calculations, of the
millions upon millions of individuals who have had their
prints classified, no two fingerprints have been found to be
identical.
15-5
PRINCIPLES OF FINGERPRINTS
First Principle: A fingerprint is an
individual characteristic; no two
fingers have yet been found to
posses identical ridge
characteristics.
bsapp.com
PRINCIPLE ONE - MINUTIAE
•The individuality of a fingerprint is not determined by its
general shape or pattern, but by the careful study of its
ridge characteristics, known as minutiae. Video
•It is the identity, number, and relative location of these
minutiae that imparts individuality to a fingerprint.
•There are as many as 150 minutiae on the average finger.
•After a three year study, it was determined that “no valid
basis exists for requiring a predetermined minimum
number of friction ridge characters which must be present
in two impressions in order to establish positive
identification.”
•In a judicial proceeding, an expert must demonstrate a
point-by-point comparison in order to prove the identity of
an individual.
15-7
PRINCIPLES OF FINGERPRINTS
Second Principle: A fingerprint
will remain unchanged during
an individual's lifetime.
bsapp.com
JOHN DILLINGER
bsapp.com
Fingerprint Identification
When minutiae on two different prints match, these are called
points of similarity or points of identification. At this point there
is no international standard for the number of points of
identification required for a match between two fingerprints.
However, the United Kingdom requires a minimum sixteen points
while Australia requires twelve.
Automated Fingerprint Identification System (AFIS)
AFIS is a computerized system capable of
reading, classifying, matching, and storing
fingerprints for criminal justice agencies. Quality
latent fingerprints are entered into the AFIS for a
search for possible matches against the state
maintained databases for fingerprint records to
help establish the identity of unknown deceased
persons or suspects in a criminal case.
http://www.fdle.state.fl.us/CrimeLab/images/fingerrint%20comparison%20for%20afis.jpg
PRINCIPLES OF FINGERPRINTS
Third Principle: Fingerprints
have general ridge patterns
that permit them to be
systematically classified.
bsapp.com
Ridgeology: The study of the uniqueness of friction ridge structures
and their use for personal identification.1
As we have learned in our first lesson, a
fingerprint is made of a series of ridges and
valleys on the surface of the finger. The
uniqueness of a fingerprint can be determined by
the pattern of ridges and valleys as well as the
minutiae points, which are points where the ridge
structure changes.
The koala is one of the few mammals (other than primates) that
has fingerprints. In fact, koala fingerprints are remarkably
similar to human fingerprints; even with an electron microscope,
it can be quite difficult to distinguish between the two.
1Introduction
to Basic Ridgeology by David Ashbaugh, May 1999
Image from http://www.cs.usyd.edu.au/~irena/minutia.gif
Ridge Characteristics
Use these characteristics as points of identification when comparing fingerprint
samples. The more points you can find in common, the better the match!
Ridge Characteristics
Crossover
Core
Bifurcation (fork)
Ridge ending
Scar
Island
Delta
Pore
http://cnx.org/content/m12574/latest/properties.jpg
PRINCIPLE TWO
•The epidermis is the outer layer of the skin, while the
dermis is the inner layer of the skin.
1515
PRINCIPLE T WO
•The dermal papillae is the layer of cells between the epidermis
and dermis, that is responsible for determining the form and
pattern of the ridges on the surface of the skin.
•Once the dermal papillae develop in the human fetus in the
10th week of pregnancy, the ridge patterns will remain
unchanged throughout life except to enlarge during growth.
•Each skin ridge is populated with pores leading to sweat
glands from which perspiration is deposited on the skin.
•Once the finger touches a surface, perspiration, along with oils
that may have been picked up by touching the hairy portions of
the body, is transferred onto that surface, leaving the finger’s
ridge pattern (a fingerprint).
1516
FINGERPRINT CLASSES
There are 3 specific classes for all fingerprints based
upon their visual pattern: arches, loops, and whorls.
Each group is divided into smaller groups
as seen in the lists below.
Arch
Plain arch
Tented arch
Loop
Radial Loop
Ulnar loop
Whorl
Plain whorl
Central pocket whorl
Double loop whorl
Accidentical
INTERESTING INFO
Fingerprint Factoid:
60% of people have loops, 35% have whorls,
and 5% have arches
Did you know?
Dactyloscopy is the study of fingerprint identification.
Police investigators are experts in collecting
“dactylograms”, otherwise known as fingerprints.
PRINCIPLE THREE – LOOPS
•All fingerprints are divided into three classes on the basis of
their general pattern: loops, arches, and whorls (L.A.W.).
•A loop must have one or more ridges entering from one side of
the print, recurving, and exiting from the same side.
•If the loop opens toward the little finger, it is called an ulnar
loop.
•If the loop opens toward the thumb, it is called a radial
loop.
•All loops must have one delta, which is the ridge point at or
directly in front of the point where two ridge lines (type lines)
diverge.
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LOOPS
Loops must have one delta and one or more ridges that enter and
leave on the same side. These patterns are named for their positions
related to the radius and ulna bones.
Delta
Radial Loop (Right
Thumb)
Loop opens toward
thumb or the radial bone.
Ulna Loop (Right Thumb)
Loop opens toward the
little finger or the ulna bone.
NOTE: On the left hand, as you look at it; a loop that opens to the left would
be an radial loop, while one that opens to the right would be a ulna loop.
WHORLS
Whorls have at least one ridge that makes (or tends to make) a
complete circuit. They also have at least two deltas. If a print has
more than two deltas, it is most likely an accidental.
Plain
Whorl
Central
Pocket
Whorl
Draw a line between the two deltas in the plain and central pocket
whorls. If some of the curved ridges touch the line, it is a plain
whorl. If none of the center core touches the line, it is a central
pocket whorl.
WHORLS – PART 2
Double Loop Whorl
Accidental Whorl
Delta
Delta
Double loop whorls are
made up of any two loops
combined into one print.
Accidental whorls contain two
or
more
patterns
(not
including the plain arch), or
does not clearly fall under any
of the other categories.
PRINCIPLE THREE - WHORLS
Whorls are divided into four groups: plain, central pocket
loop, double loop, and accidental.
All whorl patterns have type lines and a minimum of two
deltas.
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ARCHES
Arches are the simplest type of fingerprints that are formed by
ridges that enter on one side of the print and exit on the other. No
deltas are present.
Spike or “tent”
Plain Arch
Ridges enter on one side and
exit on the other side.
Tented Arches
Similar to the plain arch,
but has a spike in the center.
PRINCIPLE THREE- ARCHES
•Arches, the least common of the three general patterns, are
divided into two distinct groups: plain arches and tented arches.
•The plain arch is formed by ridges entering from one side of the
print, rising and falling, and exiting on the opposite side (like a
wave).
•The tented arch is similar to the plain arch except that instead of
rising smoothly at the center, there is a sharp upthrust or spike,
or the ridges meet at an angle that is less than 90 degrees.
•Arches do not have type lines, deltas, or cores.
•
1525
DIRECTIONS- ROLL…DON’T SLIDE
1st – Roll the “pad” portion of your thumb over
the ink pad from the left side of your thumb to the
right. You do not have to push down really hard!
2nd – Roll the “pad” portion of your thumb from the left side of
your thumb to the right in the correct box on your paper to make a
thumbprint. If you slide or push too hard, the valleys will fill with
ink and you will get a solid BLOB …. Practice to get it right.
3rd – Continue this process to make a fingerprint of all ten fingers
on the “My Prints” worksheet.
4th –Use your notes and a magnifying lens to help you figure out
what type of pattern is found in each of your fingerprints. Label
each one with the pattern’s name.
AFIS COMPUTERIZED FINGERPRINTS
•The heart of AFIS technology is the ability of a computer to
scan and digitally encode fingerprints so that they can be
subject to high-speed computer processing.
•AFIS aids in classifying and retrieving fingerprints by
converting the image of a fingerprint into digital minutiae that
contain data showing ridges at their points of termination (ridge
endings) and their branching into two ridges (bifurcations).
Video
1527
D I G I TA L I M A G I N G
•Digital imaging is the process by which a picture is converted
into a digital computer file.
•With the help of digital imaging software, fingerprints, which are
often not in perfect condition, can now be enhanced for the most
accurate and comprehensive analysis.
•An important and useful tool, especially for fingerprint
identification, is the compare function that places two images
side by side and allows the examiner to chart the common
features on both images simultaneously.
1528
AFIS COMPUTERIZED FINGERPRINTS
•When the search is complete (a computer can make thousands
of comparisons per second), the computer produces a list of file
prints that must be examined by a trained fingerprint expert.
•Once the finger touches a surface, body perspiration and/or oils
present on the finger ridges are transferred to that surface,
leaving an impression.
•Prints deposited in this manner are invisible to the eye and are
commonly referred to as latent or invisible fingerprints.
•Visible prints are made when fingers touch a surface after the
ridges have been in contact with a colored material such as
blood, paint, grease, or ink.
Crystal Violet
Inked
1529
VISIBLE PRINTS
•Plastic prints are ridge impressions left on a soft material, such
as putty, wax, soap, or dust.
•Locating visible or plastic prints at the crime scene normally
presents little problem to the investigator, because these prints
are usually distinct and visible to the eye.
1530
LATENT PRINTS
Latent finger prints are those that are not visible
to the unaided eye.
When you touch things you leave traces of
proteins (amino acids), oils, sweat and acids
coming from the pores of your ridges.
If they are not smeared, the residue oils and
proteins can react with chemicals and even UV
light to become visible.
Finding latent prints can be time consuming and
costly.
VIDEO
FINDING LATENT PRINTS
VIDEO
Because they are invisible to the naked eye, these
prints are difficult to find for further study and
analysis.
The old method is to just lightly dust around a crime
scene with black powder and see what develops.
Newer methods include using a portable UV optical
system named RUVIS (Reflected Ultraviolet Imaging
System) that makes proteins glow as they absorb and
reflect UV light.
DEVELOPING LATENT PRINTS
Prints on a hard and nonabsorbent surface such
as glass, tile and painted wood require different
development procedures from soft and porous
surfaces such as papers, cardboard and cloth.
--Developing prints on hard surfaces that do not
absorb the oils is easier than porous things.
--Powders work well on hard surfaces.
--Porous things require development by
precipitating chemical reactions, such as
Physical Developer (silver nitrate) or superglue.
DUSTING FOR LATENT PRINTS
Prints may be collected from hard non-porous
surfaces by revealing them with a dusting of black
powder and then lifted with a piece of clear tape.
Fluorescent colors of powder are easily seen with
UV radiation.
Did you know? Camel hair is the most
common animal hair used to make fingerprint
brushes. Now many brushes (like the one
above) are made out of fiberglass.
DUSTING FOR LATENT PRINTS
Some investigators use fluorescent powder and UV
lights to help them find latent prints on multi-colored
or dark surfaces. Powders, available in a variety
of colors, can be applied with a brush or
magnetic wand, and adhere to perspiration
and/or body oils of the print. Always take a
picture of the print before tape lifting it.
Magnetic powder can also be used to reveal latent
prints. This type of powder works better on shiny
surfaces or plastic baggies or containers.
D E V E L O P I N G L AT E N T P R I N T S
•Super Glue® fuming develops latent prints on nonporous
surfaces, such as metals, electrical tape, leather, and plastic
bags. The active ingredient is cyanoacrylate
•Development occurs when fumes from the glue adhere to
the print, usually producing a white latent print. Super Glue®
is approximately 98 to 99 percent cyanoacrylate ester, a
chemical that actually interacts with and visualizes a latent
fingerprint. Very dangerous to breath.
video
1536
DETECTING PRINTS
Iodine fuming involves heating iodine crystals that cause
vapors which combine with latent prints to make them
visible. Iodine prints are not permanent and will fade,
making it necessary to photograph the prints immediately.
These fumes are very toxic to breathing humans.
•Physical Developer is a silver nitrate-based reagent used to
develop prints when other chemical methods are ineffective.
It is used on porous items that may have been wet. It
washes away proteins and is therefore a last resort.
1537
DETECTING PRINTS
•Ninhydrin reacts chemically with trace amounts
of amino acids present in perspiration. It
produces a purple-blue color. Very popular today
due to sensitivity and ease of application.
DETECTING PRINTS WITH FLUORESCENCE
•The high sensitivity of fluorescence serves as the
underlying principle of many of the new chemical
techniques used to visualize latent fingerprints.
•Fingerprints are treated with chemicals that would induce
fluorescence when exposed to lasers, or high-intensity light
sources (“alternate light sources”) such as quartz halogen,
xenon arc, or indium arc light sources.
•Once the latent print has been visualized, it must be
permanently preserved for future comparison and for
possible use as court evidence.
•A photograph must be taken before any further attempts at
preservation are made, such as tape lifting.
1539
T R A N S P O R T I N G L AT E N T F I N G E R P R I N T S
•If the object is small enough to be transported without
destroying the print, it should be preserved in its entirety.
•Prints on large immovable objects that have been developed
with a powder can best be preserved by “lifting” with a broad
adhesive tape. Take a close up picture before attempting to lift.
•Then, the tape is placed on a properly labeled card that
provides a good background contrast with the powder.
1540
Directions for Latent Fingerprint Lab:
video
1 - Cover your table with white butcher paper or newspaper. You must dust
everything on the paper!
2 - Get a lifting kit from your teacher that contains black powder, brushes, and
clear tape.
3 - Press the pad of your right thumb on a CD or glass slide to make a print.
Place on the paper covering your table.
4 – Dip a brush lightly into the container of black powder and then tap off the
extra on the lid. You only need a very small amount of powder to dust the
print.
5 – Hold the brush over the print and rotate it between your thumb and
fingers. Use the brush to remove any extra powder.
6 - Use a small piece of clear tape to lift the print and place it in the box on
your worksheet.
CAUTION: The black powder will be messy and isn’t easy to
clean up. Don’t dust anything without permission!
How many ridge characteristics can you identify in this fingerprint?
http://www.dkfz.de/tbi/projects/bmcv/images/iu_it246_04s_fingerprint1.jpg
IDENTIFY EACH FINGERPRINT PATTERN.
Right Hand
Left Hand
Right Hand
Right Hand
Left Hand
It’s time to make
some prints!
Video link
Avoid
Partial
Prints
GOOD PRINT
Get as much of the top part
of your finger as possible!