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Unit I: Fingerprinting

Unit I: Fingerprinting(Essential Questions)

1) What is the history of fingerprinting?

2) Why is fingerprint evidence considered direct evidence?

3) Why are fingerprints individual evidence?

4) Why may there be no fingerprint evidence at a crime scene?

5) How are fingerprints made?

6) What characteristics define fingerprints?

7) What are the basic types of fingerprints?

8) What is the difference between latent, plastic, and visible fingerprints?

9) How have computers made personal identification more efficient?

10) What are the methods used for “lifting” fingerprints from various surfaces?

11) How are fingerprints analyzed?

12) Can fingerprints be altered?

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Dactyloscopy

The study of fingerprints• Several ancient cultures used fingerprints as markings

• Fingerprints in clay contracts from 1792-1750 B.C. in Babylon

• In ancient China, used inked fingerprints on official documents (oldest known from 3rd

century B.C.)

• Dr. Nehemiah in 1684 wrote a paper describing the patterns he saw under a microscope

• Johann Mayers in 1788 wrote a paper describing the “arrangement of skin ridges is never duplicated in two persons.” (First to recognize this fact.)

• Jan Purkyn in 1823 recognized 9 distinct fingerprint patterns

• William Herschel in 1856 required Indians to put their fingerprints on contracts, and also as a means of identifying prisoners (1877)

• Henry Faulds—claimed that fingerprints did not change over time and that they could be classified for identification

• Alphonse Bertillon in 1879 proposed body measurements as a means of identification; termed anthropometry

• Francis Galton and Edward Richard Henry in 1888 instituted a numerical classification system

• Juan Vucetich in 1891 developed a fingerprint classification based on Galton’s that is used in Spanish-speaking countries

Bertillion Measurements(1880’s)

•Alphonse Bertillion was a ledger clerk in Paris who began taking body measurements

•Practice of anthropometry

•Successful for identification until Leavenworth Prison in 1903

•William West and Will West:2 men with similar measurements that looked almost alike, had almost identical measurements , but had different fingerprints

•Look at Table 4.1 in your text

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Will West William West

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So…What is a fingerprint and why do we have them, and how do we leave them?

• What?

– Raised portions of the skin, arranged in connected units called dermal, or friction ridges.

• Why?

– Help us with our grips on objects we touch.

• How?

– Caused by natural secretions of the sweat glands present in the friction ridges. Secretions are a combination of mainly water, oils, and salts. Dirt from everyday activities also mixes in. This combination is what’s left behind when you leave a fingerprint.

Kendall/Hunt Publishing Company8

Fundamental Principles

of Fingerprints A fingerprint is an individual characteristic; not

even identical twins have the same one.

Formed during 10th week of pregnancy-the

creation occurs in the basal layer of the skin

(within the epidermis)

Part genetic, part environmental

A fingerprint will remain unchanged during an

individual’s lifetime.

Fingerprints have general characteristic ridge

patterns that permit them to be systematically

classified.

Will grow back if attempts are made to

eliminate or alternate

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WARNING!

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So that whole skin thing…

•Refer to Figure 4.1 in your text

•Skin is made up of an outer epidermal layer separated from the inner dermal layer by papillae

•Papillae is what determines the structure of the friction ridges.

•Sweat pores along the ridges release perspiration

•98-99% Water-after the water evaporates, we’re left with a print made up of ½ salt, ½ organic compounds and dirt etc. About 1 microgram of material to work with.

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Three types of fingerprints…

•Patent Fingerprints: visible prints found at a crime scene

•Left on a smooth surface when blood, ink, grease, chalk, mud or even dust comes into contact with a finger.

•Plastic Fingerprints: actual indentations

•Left in soft material like clay, putty, wax, or gum

•Latent Fingerprints: hidden prints caused by the transfer of oils and other body secretions onto a surface

•Can be made visible by dusting with powders or chemical reactions

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LOOP WHORLARCH


Arch~5% of population

An arch has friction

ridges that enter on one

side of the finger and

cross to the other side

while rising upward in the

middle. They do NOT

have type lines, deltas,

or cores.

Types

Plain

Tented

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Loop~65% of the population

A loop must have one or

more ridges entering and

exiting from the same side.

Loops must have one delta.

Types

Radial—opens toward the

thumb

Ulnar—opens toward the

“pinky” (little finger)

Which type of loop is this, if it

is on the right hand? Left

hand?

Right-Ulnar; Left-Radial


Whorl~30% of the population

A plain or central pocket whorl

has at least one ridge that

makes a complete circuit. A

double loop is made of two

loops. An accidental is a

pattern not covered by other

categories. Whorls have at

least two deltas and a core.

Types Plain

Central Pocket

Double Loop

Accidental

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Ridge CharacteristicsMinutiae-characteristics of ridge patterns


Fingerprint Minutiae

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Printing a Ten Cardhttp://www.youtube.com/watch?v=d7N-4UNAzsw

1. Fold the ten card along the line between the right-hand fingers and those of the left hand.

2. Place the fingerprint card on the front edge of the table.

3. Starting with the right hand, ink the thumb from side to side from fingernail edge to fingernail edge and from the first joint to the tip of the finger.

4. Working from the inside to the outer edge, place the thumb in the first square of the card and gently roll side to side using constant pressure. DO NOT ROCK BACK AND FORTH. MAKE ONLY ONE WIPE. A good print should include from the joint of the finger to the tip.

5. Continue to ink and roll each finger, printing them in order in the squares on the ten card.

6. When you’re finished, fold the card so that the squares for printing the left hand are closest to the edge of the table.

7. Repeat steps 3-5 with the left hand.

8. Re-ink the fingers of the right hand and press them gently into the box labeled “first four” for the right hand. Do the same for the right thumb and place the print in the box labeled right thumb.

9. Repeat for the left hand.

How do you measure up?

• Now that you’ve taken your own ten card…

– Look at each of your fingers and determine which pattern you primarily exhibit…arch, whorl, or loop. Once determined, compare with the class

– How do you and the class compare with the population averages?

– Look at the prints from both hands, are they the same exact print? Is your left index finger the same as your right etc?

– Try to identify some of the minutiae that exist on your index finger…how many can you find?

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Henry Classification System

• Edward Henry developed a system later modified by FBI

• Allowed all sets of 10 prints to be put into 1,024 categories

• Created secondary classifications to individualize even more

• Weeds out prints so only a dozen or so have to be examined by hand (computers make the first cut and then manual examinations are done)

• 1st step is to figure out how many of your fingers have whorls

• 2nd step is to give each pattern a number based on which finger has the whorl and set up a fraction.

• These numbers are set up like a fraction and a one added to both the numerator and the denominator.


Primary ClassificationThe Henry—FBI Classification

Each finger is given a point value based on the

presence of a whorl.

right left

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Primary Classification

Assign the number of points for each finger that has a

whorl and substitute into the equation:

That number is your primary classification number.

How many people in the class have that classification number?

=

Now try this at home…

• Take prints from a family member (we’ll return them to their owner when we finish with them).

• Identify their pattern of prints.

• Give them a primary classification number with the Henry classification system.

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Comparison

There are no legal

requirements in the

United States on the

number of points.

Generally, criminal

courts will accept 8 to 12 points of similarity. (There are generally 150-200 minutiae in a properly rolled print.)

Check it out!

Look at the fingerprint handout…identify the minutiae in the fingerprint using the pictures seen earlier in the presentation. Use a colored pencil or pen to outline the minutiae if necessary.

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Who done it?• Try these

matching activities…can you figure out which print matches those found at the scene?

• Now match the prints made by the same finger.


Latent Prints

Latent fingerprints are those that are not visible to the

naked eye. These prints consist of the natural

secretions of human skin and require development for

them to become visible.

Most secretions come from three glands:

Eccrine—largely water with both inorganic

(ammonia, chlorides, metal ions, phosphates) and

organic compounds (amino acids, lactic acids, urea,

sugars). Most important for fingerprints.

Apocrine—secrete pheromones and other organic

materials.

Sebaceous—secrete fatty or greasy substances.

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Developing Latent Prints

Developing a print requires substances that interact with secretions

that cause the print to stand out against its background. It may be

necessary to attempt more than one technique, done in a particular

order so as not to destroy the print.

Powders—adhere to both water and fatty deposits. Choose a

color to contrast the background.

Iodine—fumes react with oils and fats to produce a temporary

yellow brown reaction.

Ninhydrin—reacts with amino acids to produce a purple color.

Silver nitrate—reacts with chloride to form silver chloride, a material which turns gray when exposed to light.

Cyanoacrylate—“super glue” fumes react with water and other fingerprint constituents to form a hard, whitish deposit.

In modern labs and criminal investigations, lasers and alternative light sources are used to view latent fingerprints. These were first used by the FBI in 1978. Since lasers can damage the retina of the eye, special precautions must be taken.


Iodine Fingerprint

Ninhydrin Fingerprint


Cyanoacrylate Fingerprints

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So what other prints can be used?


Other Prints Palm—friction ridges can be identified and may be used against

suspects.

Ears—shape, length and width

Lips—display several common patterns

Teeth—bite marks are unique and can be used to identify

suspects

Voice—electronic pulses measured on a spectrograph

Foot—size of foot and toes; friction ridges on the foot

Shoes—can be compared and identified by type of shoe, brand,

size, year of purchase, and wear pattern.

Eyes-The blood vessel patterns in the eye may be unique to

individuals.

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Other Prints

Lips—display several

common patterns

Short vertical lines

Short horizontal lines

Crosshatching

Branching grooves


AFIS“Automated Fingerprint Identification System”

http://www.youtube.com/watch?v=ZKi1CKTRCQM

AFIS - a computer system for storing and retrieving fingerprints

Began in the early 1970’s to: Search large files for a set of prints taken from an individual

Compare a single print, usually a latent print developed from a crime scene

By the 1990’s most large jurisdictions had their own system in place. The problem - a person’s fingerprints may be in one AFIS but not in others

IAFIS—the FBI’s Integrated Automated Fingerprint Identification system which is a national database of all 10-print cards from all over the country

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Biometrics Use of some type of body metrics for the purpose of

identification. (The Bertillon system may actually have been

the first biometry system.)

Used today in conjunction with AFIS

Examples include retinal or iris patterns, voice recognition,

hand geometry

Other functions for biometrics—can be used to control entry

or access to computers or other structures; can identify a

person for security purposes; can help prevent identity theft

or control social services fraud.

ReferencesBall-Deslich, B, & Funkhouser, J (2009). Forensic Science for High School.Dubuque, Iowa: Kendall/Hunt.

Bertino, A (2008). Forensic Science: Fundamentals and Investigations. Mason, OH: South-Western Cengage Learning.

Evans, C. (1998). The Casebook of Forensic Detection: How Science Solved 100 of the World's Most Baffling Crimes . New York, NY: John Wiley & Sons.

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