ACOS 2.2, 2.3

FingerprintsFingerprints

Pleasant Valley High SchoolPleasant Valley High SchoolForensic ScienceForensic Science

Fingerprinting Lab Follow my verbal directions for this lab.

You will have two days to complete this lab.

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Catalyst Examine your thumbs on both hands.

Record any observations you have about both thumbprints.

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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.

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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

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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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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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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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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

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.

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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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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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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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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”

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

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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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Print Types Three categories: Loops, Whorls, and

Arches 65% of population has loops 30% has whorls 5% has arches

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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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Two major Loop Types Ulnar Loop- loop opens toward the little

finger Radial Loop- loop opens toward the thumb

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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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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

ACOS 2.2, 2.322 Central Whorl Plain Whorl

Accidental Whorl Double Loop Whorl

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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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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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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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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

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.

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Skin Layers Outer layer of skin:

Epidermis Inner layer of skin:

Dermis Layer separating the

2 layers: papillae

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

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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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Anatomy of a FP

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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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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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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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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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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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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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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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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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Digital Imaging Computers can

enhance and darken the print to make an easier image to read

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