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FINGERPRINTS
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History
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The first systematic attempt at personal identification wasdevised 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 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.
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History
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Dr. Juan Vucetich devised a classification system still used inmost Spanish-speaking countries, while Sir Edward Henry
devised another classification system used in most English-
speaking countries.
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Dr. Juan Vucetich
In 1892, two children were found brutally murdered in their home in
Argentina. The 27-year-old mother, Francisca Rojas, also had her throat cut.
Police looked into her neighbor Pedro Ramón Velázquez., but he had an alibi,
having been out with several friends at the time of the murders.
A bloody print was found on a door post. Remembering the training he
received from Juan Vucetich, Police Inspector Alvarez removed the section ofthe door with the impression and then requested Rojas be fingerprinted.
He compared the impression on the door to that of Rojas and matched it to
her. When confronted with this evidence, Rojas broke down and confessed to
the murders. Rojas' boyfriend had been overheard saying he would marry her
"except for those two brats". As a result of the Rojas murders, Argentina became the first country in the
world to abolish anthropometry and file its criminal records based solely on
fingerprint classification. Vucetich's classification system is still used in many
South American countries today.
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History
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In 1903, when the Bertillion system could not distinguishbetween two men (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.
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Fingerprint Principles
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Fingerprints are a reproduction of friction skinridges found on the palm side of the fingersand 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 ridgecharacteristics;
(2) a fingerprint will remain unchanged during an individual’slifetime; and
(3) fingerprints have general ridge patterns that permit them
to be systematically classified.
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Fingerprint ridge characteristics.
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A fingerprint exhibit illustrating the matching ridge
characteristics between the crime-scene print and an
inked impression of one of the suspect’s fingers.
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Principle One
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Mathematically, the probability for the existence of twoidentical fingerprint patterns in the world’s population isextremely small.
Besides theoretical calculations, of the millions upon millionsof individuals who have had their prints classified, no two
fingerprints have been found to be identical. The individuality of a fingerprint is not determined by its
general shape or pattern, but by the careful study of itsridge characteristics, known as minutiae.
It is the identity, number, and relative location of theseminutiae that imparts individuality to a fingerprint.
There are as many as 150 minutiae on the average finger.
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Types of minutiae
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Principle One
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After a three year study, it was determined that “novalid basis exists for requiring a predeterminedminimum number of friction ridge characters whichmust be present in two impressions in order toestablish positive identification.”
In a judicial proceeding, an expert must demonstratea point-by-point comparison in order to prove theidentity of an individual.
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Principal Two
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The epidermis is the outer layer of the skin, while thedermis is the inner layer of the skin.
The dermal papillae is the layer of cells between theepidermis and dermis, that is responsible for
determining the form and pattern of the ridges onthe surface of the skin.
Once the dermal papillae develop in the human fetus,the ridge patterns will remain unchanged throughout
life except to enlarge during growth. Thus, afingerprint will remain unchanged during anindividual’s lifetime.
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Cross-section of human skin.
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Principle Two
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Each skin ridge is populated with pores leading tosweat 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 touchingthe hairy portions of the body, is transferred onto
that surface, leaving the finger’s ridge pattern (a
fingerprint).
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Principle Three
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All fingerprints are divided into three classes on the basisof their general pattern: loops, arches, and whorls (L.A.W.)
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Principle Three
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A loop must have one or more ridges entering fromone side of the print, recurving, and exiting from thesame side.
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Principle Three
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If the loop opens toward the littlefinger, it is called an ulnar loop.
If the loop opens toward the thumb,it is called a radial loop.
Delta
L – Radial Loop
R - Ulnar Loop L – Ulnar Loop
R - Radial Loop
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Principle Three
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All loops must have one delta, which is the ridge point ator directly in front of the point where two ridge lines(type lines) diverge.
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Principle Three
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Whorls are divided into four groups: plain, centralpocket loop, double loop, and accidental.
All whorl patterns have type lines and a minimum oftwo deltas.
A plain whorl and a central pocket loop have at leastone ridge that makes a complete circuit.
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Principle Three
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Draw a line between the two deltas in the plain andcentral pocket whorls. If some of the curved ridgestouch the line, it is a plain whorl. If none of thecenter core touches the line, it is a central pocketwhorl.
Plain
Whorl
Central
PocketWhorl
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Principle Three
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The double loop is made up of two loops combinedinto one fingerprint.
An accidental either contains two or more patterns,or is a pattern not covered by the other categories.
Delta
Delta
Double Loop Whorl Accidental
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Principle Three
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Arches, the least common of the three generalpatterns, are divided into two distinct groups: plainarches and tented arches.
The plain arch is formed by ridges entering from one
side of the print, rising and falling, and exiting on theopposite side (like a wave).
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Principle Three
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The tented arch is similar to the plain arch exceptthat instead of rising smoothly at the center, there is asharp upthrust or spike, or the ridges meet at anangle that is less than 90 degrees.
Arches do not have type lines, deltas, or cores.
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Latent Prints
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Once the finger touches a surface, body perspirationand/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 invisiblefingerprints.
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Visible Prints
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Visible (patent) prints are made when fingerstouch a surface after the ridges have been incontact with a colored material such as blood,paint, grease, or ink.
Plastic prints are ridge impressions left on asoft material, such as putty, wax, soap, or dust.
Locating visible or plastic prints at the crimescene normally presents little problem to the
investigator, because these prints are usuallydistinct and visible to the eye.
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Latent Prints
Once located, the crime scene investigator candevelop the print in the most appropriate fashion.
Latent prints deposited on hard and nonabsorbent
surfaces (e.g., glass, mirror, tile, and painted wood) are
preferably developed by the application of a powder. Whereas prints on porous surfaces (e.g., papers,
cardboard, and cloth) generally require treatment
with a chemical.
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Porous Surfaces
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Types of Evidence Paper items
Cardboard
Unfinished wood Examiners use various chemical methods to visualize
latent prints on porous surfaces, such as iodinefuming, ninhydrin, and Physical Developer.
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Porous Evidence
Processing Techniques 1,2-Indanedione (IND)
Ninhydrin (NIN)
1,8-Diazafluoren-9-One (DFO)
Oil Red O (ORO) Iodine Fuming (IF)
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IND NIN IFORO
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Detecting Prints
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Ninhydrin reacts chemically with trace amounts ofamino acids present in latent prints to produce apurple-blue color.
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Non-Porous Evidence
Types of Evidence Plastic
Glass
Metal
Non-adhesive side of tape
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Non-Porous Evidence
Processing Techniques Cyanoacrylate Ester
Superglue (SG)
Powders
Black, magnetic, fluorescent
Fluorescent Dye Stain
Rhodamine 6G (R6G)
RAM
Amido Black
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Detecting Prints
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Powders, available in a variety of colors, can beapplied with a brush or magnetic wand, and adhere toperspiration and/or body oils of the print.
Super Glue® fuming develops latent prints onnonporous surfaces, such as metals, electrical tape,leather, and plastic bags. Development occurs when fumes from the glue adhere to
the print, usually producing a white latent print.
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Detecting Prints
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Super Glue® is approximately 98 to 99 percentcyanoacrylate ester, a chemical that actually interactswith and visualizes a latent fingerprint.
Super Glue fuming can be accomplished by usingeither a fuming chamber (for up to six hours) or a
handheld wand that heats a small cartridge containingcyanoacrylate.
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Amido Black
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Detecting Prints
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The high sensitivity of fluorescence serves as theunderlying principle of many of the new chemicaltechniques used to visualize latent fingerprints.
Fingerprints are treated with chemicals that wouldinduce fluorescence when exposed to lasers, or high-
intensity light sources (“alternate light sources”) suchas quartz halogen, xenon arc, or indium arc lightsources.
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Detecting Prints
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Once the latent print has been visualized, it must bepermanently preserved for future comparison and forpossible use as court evidence.
A photograph must be taken before any further
attempts at preservation are made.
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Transporting Prints
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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.
Then, the tape is placed on a properly labeled card that
provides a good background contrast with the powder.
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Digital Imaging
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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.
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Comparison
3 Levels of Detail: Level 1: Overall Ridge flow, pattern types
Level 2: Ridge paths, minutiae
Level 3: Size and shapes of pores and ridges,
incipient ridges, scars
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Comparison- Level 1
Overall ridge flow, pattern Arches: plain & tented (5%)
Whorls: plain, central pocket loop, double loop, accidental (30-35%) Loops : radial & ulnar (60-65%)
Exclusions can occur at this level
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Comparison-Level 2
Individual ridge path, minutiae Different degrees of rarity in minutiae
Identification occurs at this level
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Comparison-Level 3
Ridge shape - ridge width and shape, pores, edge contour,
incipient ridges, creases, scars
Can support ID’s
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Evaluation
Look at all the information between the latent print and
known print
Quality and quantity of similarities or differences to render a
conclusion
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Verification
All latent print identifications areindependently examined by another
competent latent print examiner (ACE)
Verification/2nd Verification
Blind Verification
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IAFIS
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AFIS
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The heart of AFIS technology is the ability of acomputer to scan and digitally encode fingerprints sothat they can be subject to high-speed computerprocessing.
AFIS aids in classifying and retrieving fingerprints by
converting the image of a fingerprint into digitalminutiae that contain data showing ridges at theirpoints of termination (ridge endings) and theirbranching into two ridges (bifurcations).
When the search is complete (a computer can makethousands of comparisons per second), the computerproduces a list of file prints that must be examined by atrained fingerprint expert.
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IAFIS
Not only fingerprints, but corresponding criminal histories;
mug shots; scars and tattoo photos; physical characteristics like
height, weight, and hair and eye color; and aliases.
The system also includes civil fingerprints, mostly of individuals
who have served/are serving in the U.S. military or have been
or are employed by the federal government.
In the summer of 2014, IAFIS was replaced by Next
Generation Identification program (NGI) which provides
automated fingerprint and latent search capabilities, electronic
image storage, and electronic exchange of fingerprints to morethan 18,000 law enforcement agencies and other authorized
criminal justice partners 24 hours a day, 365 days a year.
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Comparison
ACE-V Analysis
Comparison
Evaluation
Verification
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Questions?