Finger print revised jan 10

Fingerprints

Chapter 4

FingerprintsFingerprints

2Kendall/Hunt Publishing Company

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You will understand:

Why fingerprints are individual evidence.

Why there may be no fingerprint evidence at a crime scene.

How computers have made personal

identification easier.

Objectives

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You will be able to:Define the three basic properties that allow

individual identification by fingerprints.

Obtain an inked, readable fingerprint for each finger.

Recognize the general ridge patterns (loops, whorls, and arches).

Identify friction ridge characteristics and compare two fingerprints with at least ten points of identification.

Explain the differences among latent, plastic, and visible fingerprints.

Develop latent prints (make them visible) using physical and chemical methods.

Objectives, continued

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Recording and classifying prints

Rolling inked prints

Loops, whorls, arches, ridge characteristics

Primary identification number

Lifting prints

Black, white, and fluorescent powder

Chemicals—ninhydrin, iodine, silver nitrate, cyanoacrylate

Other types of prints

Palm, lip, teeth, eye, ear, voice, shoeprints, and footprints

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Fundamental Principles of Fingerprints

A fingerprint is an individual characteristic.

Made of “hills” or ridges and “valleys” or furrows

A fingerprint remains unchanged during an individual’s lifetime.

A fingerprint cannot be destroyed.

Even twins have different fingerprints.

Fingerprints have general characteristic ridge patterns that permit them to be systematically classified.

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• Patterns form on fingers during early embryo development (10th week of gestation/pregnancy)

• Person’s genetic make up plays a role in finger print ridge patterns but it is not the only factor

• The 2 features of fingerprints most important to their use as a means of personal identification:

1. Every print is unique to an individual

2. Fingerprints do not change during a life time (unless there is extensive damage to the dermal layer)

Kendall/Hunt Publishing Company7

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History of Fingerprinting Presentations Biographical information

Date of Birth Place of Birth Residence (if different than birthplace) Education Job/Career

Contributions to field of forensic science/study of fingerprints 2 cases they worked on (brief description and relevance) Picture 3 important facts

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1. Nehemiah Grew and Johannes Evangelista Purkinje2. William Herschel3. Henry Faulds4. Alphonse Bertillon5. Francis Galton6. Edward Richard Henry7. Juan Vucetich

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History from 1850 to 1900William Herschel—required Indians to put their fingerprints on contracts, and

used fingerprints as a means of identifying prisoners Henry Faulds—claimed that fingerprints did not change over time and that they

could be classified for identification

Alphonse Bertillon—proposed body measurements as a means of identification; termed anthropometry

Francis Galton—developed a primary classification scheme based on loops, arches, and whorls

Edward Richard Henry—in collaboration with Galton, instituted a numerical classification system

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

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Terminology IAFIS/AFIS

Integrated Automated Fingerprint Identification System Developed in 1999 by FBI and Law Enforcement community Prints and Criminal histories of more than 47 million people By 2007, 55 million computerized prints

Delta Triangular area found in all loop and whorl patterns; ridges go in different directions above and below the triangle

Core area found near the center of all loop and whorl patterns

Minutiae Tiny, ridge characteristics found between ridge lines or at the end of ridge lines

Patent prints Visible prints left on smooth surface when blood, ink or some other liquid comes in contact with hands and is transferred to that

surface

Plastic Prints Actual identification left in some soft material such as clay, putty, or wax Indented or molded

Latent Prints Hidden prints caused by the transfer of oils and other secretions from skin onto surface Must be developed by physical or chemical means


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Things a Fingerprint Analyst looks for

Core Delta Ridge Pattern

Loops, whorls, arches

Ridge Characteristics Minutiae

Ridge count (only some types of ridge patterns) Draw a line from the core to the edge of the delta and

count lines that the line cuts thru


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LOOP WHORL ARCH

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30% Whorls-Plain=24%-Central Pocket=2%-Double Loop=4%-Accidental/other=0.01%

65% Loops• Ulnar=60%•Radial=5%

5% Arches-Plain=4%-Tented=1%

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Arch

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

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?

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Whorl

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.

TypesPlain

Central pocket

Double loop

Accidental

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•One or more ridges that make a complete circle•2 deltas and if a line is drawn between them, no ridges in the inner pattern touch or are cut by the line

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ArchesArches 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.

Plain ArchRidges enter on one side and

exit on the other side.

Tented Arches Similar to the plain arch,

but has a spike in the center.

Spike or “tent”

LoopsLoops 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

Ulnar Loop (Right Thumb)

Loop opens toward right or the ulna bone.

Radial Loop (Right Thumb)

Loop opens toward the left or the radial bone.

NOTE: On the left hand, a loop that opens to the left would be an ulnar loop, while one that opens to the right would be a radial loop.

WhorlsWhorls 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.

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.

Plain Whorl

Central Pocket Whorl

Whorls – Part 2

Accidental Whorl

Accidental whorls contain two or more patterns (not including the plain arch), or does not clearly fall under any of the other categories.

Double Loop Whorl

Double loop whorls are made up of any two loops combined into one print.

Delta

Delta

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•Ridge patterns not enough to individualize fingerprints•Details between ridges•About 150 different characteristics on average print•Identify characteristics and the relative number

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Ridge Characteristics

Minutiae—characteristics of ridge patterns

Ridge endingIsland or short ridgeBridgeEye or enclosureDeltaBifurcation or fork DotSpurDouble bifurcationTrifurcation

Rid

ge C

har

acte

rist

ics

Use these characteristics as points of identification when comparing fingerprint samples. The more points you can find in common, the better the match!

http://cnx.org/content/m12574/latest/properties.jpg

Ridge Characteristics

Crossover

Core

Bifurcation (fork)Ridge ending

Island

Delta

Pore

Scar

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Fingerprint Minutiae

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Comparison

There are no legal

requirements in the United

States on the number of

points required for a match.

Generally, criminal courts will

accept 8 to 12 points of

similarity.

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Primary Classification

The Henry-FBI Classification System

Each finger is given a point value.

right left

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Primary Classification, continued

Assign the number of points for each finger that has a whorl and substitute into the equation:

right right left left left index ring thumb middle little + 1

right right right left left thumb middle little index ring + 1

That number is your primary classification number.

=

1 – Blow up your balloon about halfway and twist the end to keep the air from coming out. Do not tie it off!

2 – Use an ink pad to make a print with all of your fingers and label each one with a permanent marker. Write your name on the balloon as well.

3 – Blow up the balloon to full size and tie the end.

4 – Analyze the fingerprints to find several ridge structures that we have discussed. Use a highlighter to mark these structures on your “My Prints” worksheet.

Try It!

Think About It!

Which ridge structures were most common in your fingerprints?

Which ridge structures were most common in your group?

Were there any structures that were not found in any of the fingerprints?

Directions

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.

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.

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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—secretes largely water, with both inorganic (ammonia, chlorides, metal ions, phosphates) and organic (amino acids, lactic acids, urea, sugars) compounds. Most important for fingerprints.

Apocrine—secretes pheromones and other organic materials.

Sebaceous—secretes fatty or greasy substances.

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Developing Latent Prints

Developing a print requires substances that interact with secretions, causing 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 with the background.

Iodine—fumes react with oils and fats to produce a

temporary yellow-brown color.

Latent prints are impressions left by friction ridge skin on a surface, such as a tool handle, glass, door, etc.

Prints may be collected by revealing them with a dusting of black powder and then lifted with a piece of clear tape.

The cyanoacrylate fuming method (often called the super glue method) is a procedure that is used to develop latent fingerprints on a variety of objects.

Magnetic powder can also be used to reveal latent prints. This type of powder works better on shiny surfaces or plastic baggies or containers.

Some investigators use fluorescent powder and UV lights to help them find latent prints on multi-colored or dark surfaces.

Ninhydrin is a chemical that bonds with the amino acids in fingerprints and will produce a blue or purple color. It is used to lift prints from surfaces such as paper and cardboard.

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Developing Latent Prints, continued

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

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

Cyanoacrylate—“superglue” 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.

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Iodine Fingerprint

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Ninhydrin Fingerprint

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Cyanoacrylate Fingerprints

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Other Prints

Lips—several common patterns

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

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Other Prints, continued

Palm—friction ridges can be

identified and may be used

against suspects

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Footprints are taken at birth

as a means of identification of

infants.

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A man has been convicted of suffocating an eldery woman on the basis of earprint evidence. The assailant was caught after police matched the inprint of his ear on the victim’s window. Police believe that the thief put his ear to the window to listen for signs of anyone home.

Earprint catches murderer

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Teeth—bite marks are unique and

can be used to identify suspects.

These imprints were placed in gum

and could be matched to crime

scene evidence.

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The blood vessel patterns in

the eye may be unique to

individuals. They are used

today for various security

purposes.

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AFIS

The Automated Fingerprint Identification System—a computer system for storing and retrieving fingerprints

Established in the 1970s, AFIS enables law enforcement officials 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 1990s, most large jurisdictions had their own system in place. The problem: A person’s fingerprints may be in one AFIS database 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.

Systematic Approaches

Least destructive method first Analyze surface the print is on and then

determine print development method you will use Porous surfaces: paper, cloth, wood Nonporous surface: glass, metal

Recognition, Collection and Preservation of Fingerprint Evidence

Fingerprints are among the best and most probative of all types of physical evidence

Objects believed to have latent prints on their surfaces should be collected intact and submitted to lab’s latent print section for examination

If collection of object is improbable or impossible, latent print development needs to be conducted at the scene Tape lift photography

Like other evidence, print evidence needs to be carefully documented and Chain of Custody must be preserved

Fingerprint Identification relies on 4 Basic Points

Friction ridges develop during fetal growth before birth in their definitive form

Friction ridges remain unchanged throughout life with the exception of permanent scars

The friction ridge patterns and their details are unique and not repeated

The ridge patterns vary within certain boundaries, which allows the patterns to be classified

System for Latent Print Analysis: ACE-V Analysis

Analyze latent print Determine its proper orientation Decide if there are any color reversals or other unusual circumstances Decide suitability

Comparison Comparison with a known involves several levels I) overall pattern and ridge flow must be examined II) Ridge characteristics/minutiae and their location compared III) Pore shape, location, numbers and relationships as well as shape and size of edge features

are compared ANY unexplained difference during this process would result in the conclusion that the

known is excluded as a source of the latent print If every compared feature is consistent with the known and there is enough features

sufficiently unique when considered as a whole, individualization can be concluded Peer review of comparison further solidifies individualization

Evaluation 8-12 points is sufficient to make a comparison; no set number 3 evaluations:

Insufficient ridge detail to form conclusion Exclusion Individualization

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More about Prints

For additional information about prints and crime, check out truTV’s Crime Library:

www.crimelibrary.com/criminal_mind/forensics/fingerprints/1.html