acos 2.2, 2.3 fingerprints pleasant valley high school forensic science
TRANSCRIPT
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ACOS 2.2, 2.3
FingerprintsFingerprints
Pleasant Valley High SchoolPleasant Valley High SchoolForensic ScienceForensic Science
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Fingerprinting Lab Follow my verbal directions for this lab.
You will have two days to complete this lab.
ACOS 2.2, 2.3
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Catalyst Examine your thumbs on both hands.
Record any observations you have about both thumbprints.
ACOS 2.2, 2.3
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Quick Experiment You have now seen your thumbprints as
a positive imprint. What you are seeing is known to members
of the Forensics community as Friction Ridges. These lines are composed of valleys (Grooves) and hills (Friction Ridges). When you see an inked print, you are seeing the pattern of the friction ridges.
ACOS 2.2, 2.3
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Timeline of Fingerprinting
B.C. China – documents showing negative images of FP’s
1792 – 1750 B.C. – Ancient Babylon used prints to identify sculptors of clay pottery
1684 – Dr. Nehemiah writes a paper describing patterns of FP’s
1788, Johann Mayer notes individuality of FP’s
1823 – Jan Purkyn describes 9 print patterns
1856 – Sir William Hershel noted that fingerprints do not change with age
1888 – Galton and Henry develop classification systems
1891 – Ivan Vucetich made important changes to the collection process (10 digits, use cards)
1896 – Henry creates the ten card and divided FP’s into modern groups
ACOS 2.2, 2.3
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ACOS 2.2, 2.3
Early Techniques Alphonse Bertillon- system of precise body measurements
(anthropometry) Bertillon’s system rested on that body measurements never
change after the age of 20 Skeleton sizes were thought to be so diverse that no two people
could have the same measurements System included 11 measurements: outstretched arms, head
length and width, left foot length, left little finger length, trunk height, body height, width and length of right ear, length of the left forearm, sitting height
He also documented hair color, eye color, and skin tone
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ACOS 2.2, 2.3
Anthropometry For twenty years, anthrompometry was
thought to be the most accurate measurement system
Once police looked for a more efficient way to identify people, the fingerprinting system came through
Today, fingerprinting is the pillar of criminal identification
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ACOS 2.2, 2.3
Early use of Fingerprints
Documentation of Chinese using FP’s to sign legal documents as far back as 3,000 years ago
Several years before Bertillon began work, FP’s were used in India to “bind” someone to a contract
Scottish physician, Henry Fauld, published papers on the potential application of FP’s to personal identification
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ACOS 2.2, 2.3
Francis Galton 1892- published book Finger Prints He discussed the anatomy of fingerprints and
suggested techniques for recording them Galton also assigned fingerprint types: loops,
whorls, and arches His book demonstrated that no two prints are
exactly alike Prints remain unchanged year after year
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Basis for Fingerprinting
A Fingerprint is not shared by any two people
A Fingerprint remains unchanged throughout life
Fingerprints exhibit general patterns that provide a basis for classification.
ACOS 2.2, 2.3
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ACOS 2.2, 2.3
United States v. Byron C. Mitchell
Pennsylvania-1999 Admissibility of fingerprint evidence was
challenged The defense stated that the fingerprints could
not be proven to be unique under the current research
After 4 days of hearings, the judge upheld the research on fingerprints and ruled that: Human friction ridges are unique and permanent Human friction ridge skin arrangements are unique
and permanent
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ACOS 2.2, 2.3
No 2 Identical Prints
Galton calculated that there are 64 billion documented that can help to support this
Galton’s calculations were challenged and no matter what formula is used there is the same result: The probability for the existence of two identical
fingerprint patterns in the world’s population is extremely small
In 90 years of research, no two prints have ever been identical
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ACOS 2.2, 2.3
Minutiae Points AKA: Ridge Characteristics The identity, number, and relative
location of characteristics that impart individuality of a fingerprint
An easier definition: the ridges and valleys of a fingerprint
There are as many as 150 minutiae points and ridges on the average print
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ACOS 2.2, 2.3
Some Reality of prints
CSI Lies to You!!! Former CSI from the Gadsden Police
Department, Deanna Rice: “I have never lifted a complete print at a
crime scene. Tell me what criminal is stupid enough to gingerly press their fingers on a smooth surface just so I can get their fingerprints”
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Breakdown of Prints Patent Prints
When a substance such as blood, ink, paint, dirt, or grease on the perpetrators hands leave a visible print behind
Latent Prints Invisible and require dusting or other
processing/lighting to reveal Plastic Prints
Occur when perpretrator touches a soft substance such as wax, putty, butter, or even dust. Seen as a 3D image
ACOS 2.2, 2.3
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ACOS 2.2, 2.3
Latent Prints Your skin has openings called pores
that are the location of perspiration of sweat and body oils
When you make contact with a surface your body oils stick to a surface in the shape of your fingerprints
Prints left with this technique at a crime scene are called latent prints
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ACOS 2.2, 2.3
Print Types Three categories: Loops, Whorls, and
Arches 65% of population has loops 30% has whorls 5% has arches
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ACOS 2.2, 2.3
Loops A class of
fingerprints characterized by ridge lines that enter from one side of the pattern and curve around to exit from the same side of the pattern
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ACOS 2.2, 2.3
Two major Loop Types Ulnar Loop- loop opens toward the little
finger Radial Loop- loop opens toward the thumb
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ACOS 2.2, 2.3
Whorls A class of
fingerprints that include ridge patterns that are generally rounded or circular in shape and have two deltas
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ACOS 2.2, 2.3
Four distinct loop types Plain- one ridge makes a complete circle Central pocket loop- if two deltas do not
touch on the circle Double loop- two loops combined in one
fingerprint Accidental- the catch all category, if the
print does not fall into any other category
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ACOS 2.2, 2.322 Central Whorl Plain Whorl
Accidental Whorl Double Loop Whorl
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ACOS 2.2, 2.3
Arches A class of fingerprint
that is characterized by ridge lines that enter the print from one side and flow out the other side
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ACOS 2.2, 2.3
Plain arch- simplest of all prints, line enters on one side of print and exits the other side
Tented arch- sharp spike in the center of the print
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ACOS 2.2, 2.3
Unchanging Prints Similar friction ridges and minutiae can
be found on the palms of the hand and on the feet
These skin characteristics were designed by nature to enhance our grip and resist slippage
These ridges and minutiae do not change throughout life
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ACOS 2.2, 2.3
Frankensteining Can you change your fingerprints to
prevent being caught? The answer is NO!! Your fingerprints are created during
womb development You can not ever change your fingerprints You can damage or mutilate them, but
that just makes you more unique
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Mini Case Study John Dillinger, also known as Public
Enemy Number One went through much travesty to evade police He had facial reconstructive surgery and
acid washed his prints in an effort to avoid arrest. When he was finally shot and taken to the
morgue, prints taken at the morgue matched those on file already.
ACOS 2.2, 2.3
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ACOS 2.2, 2.3
Skin Layers Outer layer of skin:
Epidermis Inner layer of skin:
Dermis Layer separating the
2 layers: papillae
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Formation of FP’s An animal’s external body tissue (skin) is made up of
an inner dermis and an outer dermis FP are created in a special layer between the two
derma where new skin is produced (the basal layer) FP begin forming in the 10th week of pregnancy Because the basal layer grows faster than the two
derma, it collapses and forms intricate shapes
ACOS 2.2, 2.3
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ACOS 2.2, 2.3
Dermal Papillae Your fingerprints are determined by the
papillae layer In order to alter your prints you must
damage through the first layer of skin…ouch!!! Why not just wear gloves?
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ACOS 2.2, 2.3
Anatomy of a FP
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ACOS 2.2, 2.3
Print Classification
Henry System- adopted in 1901, looked at ridge patterns on all 10 fingers, but only accommodated 100,000 sets of prints
Primary Classification- divides all fingerprints in the world into 1024 categories Turns patterns into fractions 1/1 means that all of the fingers have the same
patterns Approximately 25% of the population have 1/1 ratio
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ACOS 2.2, 2.3
Uses of these systems
10 finger system is only of use when the investigator has the names of the suspects on hand
Can be entered into a database and matched
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ACOS 2.2, 2.3
AFIS Computer database of all fingerprints in
the country Monitored by the FBI Allows for electronic comparison of a
latent print to a known print Helps to identify suspects
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ACOS 2.2, 2.3
AFIS The computer’s search determines the degree
of correlation between the location and the relationship of minutiae of both the search and file prints
Prior to AFIS, police had to compare prints by hand to known suspects from previous cases or that had been printed already
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ACOS 2.2, 2.3
Latent Details Visible Prints- made by touching fingers
to a surface after the ridges have been in contact with colored material such as blood, ink, or paint
Plastic Prints- left on soft material such as putty, wax, soap or dust
Latent Prints- transfer of by oils and can not be seen by the naked eye
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ACOS 2.2, 2.3
Dusting for Prints Powders are brushed onto a non-
absorbent surface and will adhere to the oils left by the hand
Gray or Black powders are used to lift most all prints
Specialized clear tape known as lifting tape is used to store the print safely
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ACOS 2.2, 2.3
Fuming for Prints Exposing a piece of evidence to fumes
of super glue will expose prints Either combine cotton cloth, sodium
hydroxide and super glue OR Heat the super glue to allow evaporation
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ACOS 2.2, 2.3
Preserve the Print Photograph the print Cover with cellophane tape Place on latent print recovery card
Card should be a contrasting color to the color of the powder used
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ACOS 2.2, 2.3
Digital Imaging Computers can
enhance and darken the print to make an easier image to read
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ACOS 2.2, 2.3