chapter 14 fingerprints - welcome to rcsd · history of personal identification • ~ 8 ad:...

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PRENTICE HALL ©2008 Pearson Education, Inc. Upper Saddle River, NJ 07458

FORENSIC SCIENCE An IntroductionBy Richard Saferstein

FINGERPRINTS

Chapter 14

History of Personal Identification

• ~ 8 AD: Deliberately impressed fingerprints have been found on Chinese and Japanese documents

• 1870’s: William Herschel British official Required palm prints & impressions of right index finger from locals in India for every contract he made

History of Fingerprint IdentificationHenry Fauld

• Wrote first article about fingerprint ID: 1880, Nature magazine

• Used fingerprints to help Tokyo police in burglary case

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History of Personal IdentificationAlphonse Bertillion

• French police expert

• Developed the first systematic method of personal identification in 1883.

•

• 2 Parts• Portrait Parle:

• a detailed verbal description of the subject’s physical characteristics and dress

• Anthropometry: • Detailed description and precise measurements of the

body, including full length photographs

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Bertillion Anthropometry

The Will West Case: Downfall of the Bertillion System

• Will West was taken to Levenworth Prison • Records clerk ran his Bertillion measurements and

found they closely matched another prisoner who was serving a life sentence: William West

• Even the photograph of William West closely matched new prisoner, Will West

• Fingerprints of both were taken and found to differ• Value of fingerprint Identification was established

• Asserted all fingerprints were unique and did not change throughout life

• Categorized patterns of fingerprints into loops, arches and whorls

• Developed a classification system that allowed for a person’s fingerprints to be placed in smaller groups

History of Fingerprint IdentificationFrancis Galton

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• Devised a classification system still used in most Spanish-speaking countries,

History of Fingerprint IdentificationJuan Vucetich

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• Developed alternative classification system that was adopted in England

• His system has been modified and still is in use in the United States and Europe

• Used 5 classifications to put a set of ten fingerprints into one of thousands of classes

History of Fingerprint IdentificationSir Francis Henry

1) R Thumb

162) R Index

163) R Middle

84) R Ring

85) R Little

4

6) L Thumb

47) L Index

28) L Middle

29) L Ring

110) L Little

1

L W A L A A L L W L

The Henry Classification

System

1) R Thumb 2) R Index 3) R Middle 4) R Ring

85) R Little

6) L Thumb 7) L Index 8) L Middle 9) L Ring

110) L Little

8 + 1 1 + 1

9 2=

The sum of the values of the white squares that contain a Whorl (plus one) is the numerator of the primary classification.

The sum of the values of the dark squares that contain a Whorl (plus one) is the denominator of the primary classification.

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• 1901 - The use of fingerprinting by the New York City Civil Service Commission

• 1904 - The training of American police by Scotland Yard representatives at the 1904 World’s Fair

• 1924 - the fingerprint records of the Bureau of Investigation and Leavenworth were merged to form the identification records of the new Federal Bureau of Investigation.

History of Fingerprint IdentificationWidespread use in USA

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Fingerprint Principles

1. A fingerprint is an individual characteristic because no two fingers have yet been found to possess identical ridge characteristics.

2. A fingerprint will remain unchanged during an individual’s lifetime.

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

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Principle One• Mathematically, the probability for the existence

of two identical fingerprint patterns in the world’s population is extremely small.

• Besides theoretical calculations, of the millions upon millions of individuals who have had their prints classified, no two fingerprints have been found to be identical.

Remember the Madrid Bombing mix-up?

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Figure 14–1 Fingerprint ridge characteristics. Courtesy Sirchie Finger Print Laboratories, Inc., Youngsville, N.C., www.sirchie.com

Princpile One•The individuality of a fingerprint is determined by the careful study of its ridge characteristics, known as minutiae.

•It is the identity, number, and relative location of these minutiae that imparts individuality to a fingerprint.

•There are as many as 150 minutiae on the average finger.

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Fingerprint ridge characteristics

Fingerprint Minutiae

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Principle One• Most Fingerprints recovered at crime scenes are partial prints,

showing only a segment of the entire print.

• Under these circumstances, an expert can compare only a small number of ridge characteristics.

• In a judicial proceeding, an expert must demonstrate a point-by-point comparison in order to prove the identity of an individual.

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Figure 14–2 A fingerprint exhibit illustrating the matching ridge characteristics between the crime-scene print and an inked impression of one of the suspect’s fingers. Courtesy New Jersey State Police.

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Figure 14–3 Cross-section of human skin.

Principle Two• Fingerprints are a

reproduction of friction skin ridges found on the palm side of the fingers and thumbs.

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Structure of the Skin

Epidermis

Dermis

Hair follicle

Blood supply

Sweat gland

Nerve

Pore

Dermal papillae

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Principle Two• The epidermis is the outer layer of the skin, while the

dermis is the inner layer of the skin.• The dermal papillae is the layer of cells between the

epidermis and dermis, • is responsible for determining the form and pattern

of the ridges on the 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.

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Principle Two• Each skin ridge is populated with pores leading to

sweat glands from which perspiration is deposited on the skin.

• Once the finger touches a surface, perspiration along with oils, is transferred onto that surface, leaving the finger’s ridge pattern (a fingerprint).

• Prints deposited in this manner are invisible to the

eye and are commonly referred to as latent fingerprints.

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Principle Two• Although it is impossible to change one’s

fingerprints, some criminals have tried to obscure them.

• In order to form a permanent scar, the wound has to penetrate 1-2 mm beneath the skin’s surface.

• However, permanent scars provide a new set of fingerprint characteristics.

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John Dillinger• Tried to destroy his own fingerprints by

applying acid to them. Prints recorded at a previous arrest and compared to his postmortem prints, show that his efforts were unsuccessful.

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Mythbusters Artificial Fingerprinthttp://www.youtube.com/watch?gl=BR&hl=pt&v=MAfAVGES-Yc

http://www.youtube.com/watch?gl=BR&hl=pt&v=MAfAVGES-Yc



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Principle Three• All fingerprints are divided into three classes on the basis of

their general pattern: loops, arches, and whorls (L.A.W.).

• Categorized by the presence or absence of a delta (triangular intersection of ridges)

• An Arch has NO deltas

• A Loop has ONE delta

• A Whorl has TWO deltas

• 60 - 65% of the population have loops, 30 - 35% have whorls, and about 5% have arches.

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Fingerprint patterns

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Principle Three: Loops• A loop must have one or more ridges entering

from one side of the print, recurving, and exiting from the same side.

• loop opens toward the little finger - ulnar loop.

• loop opens toward the thumb - radial loop.

• All loops must have one delta, which is the ridge point at or directly in front of the point where two ridge lines (type lines) diverge.

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Figure 14–5 Loop pattern.

Loop Patterns

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Principle Three: Whorls• Whorls are divided into four groups: plain, central pocket loop,

double loop, and accidental.

• All whorl patterns have type lines and a minimum of two deltas.

• A plain whorl and a central pocket loop have at least one ridge that makes a complete circuit.

• The double loop is made up of two loops combined into one fingerprint.

• An accidental either contains two or more patterns, or is a pattern not covered by the other categories.

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Principle Three: Arches• Arches are divided into two distinct groups: plain arches and

tented arches.

• The plain arch is formed by ridges entering from one side of the print, rising and falling, and exiting on the opposite side (like a wave).

• The tented arch is similar to the plain arch except that instead of rising smoothly at the center, there is a sharp upthrust or spike, or the ridges meet at an angle that is less than 90 degrees.

• Arches do not have type lines, deltas, or cores.

AFIS-Automated Fingerprint Identification System

• Operates by anchoring position of fingerprint and searching database using two types of ridges:• Bifurcations• Ridge endings

• Database works by comparing prints to find ones with same number of ridges in relative positions

• Most likely matches are displayed for comparison by a fingerprint examiner

IAFISIntegrated Automated Fingerprint

Identification System

• Entirely digital system

• Compares a person’s set of ten fingerprints against a database of millions of prints in a few minutes

• Problems of incompatibility of formats is being solved by development of workstations that generate input directly into system

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Types of Crime Scene Fingerprints• Latent or Invisible Prints - caused by the

transfer of body perspiration or oils present on finger ridges to the surface of an object.

• Visible Prints (Patent Print) - a fingerprint made when the finger deposits a visible material such as ink, dirt, or blood onto a surface.

• Plastic Print - a fingerprint impressed in a soft surface.

Detection and Visualization of Fingerprints

• Patent and plastic prints are generally easy to discover

• Major challenge lies in attempting to recover latent prints from crime scene

• Different surfaces present different challenges

• Locating and visualizing prints can be done:• Reflected Ultraviolet Imaging System• Powder dusting—regular powder and magnetic• Chemical enhancement methods

Chemical Methods of Fingerprint Visualization

• Iodine fuming• iodine crystals

sublimate to iodine gas• gas adheres to fats in

the fingerprint residue

• Silver Nitrate• reacts with ions in the

sweat residue

• Ninhydrin• used for developing on porous

surfaces• reacts with amino acids

• Cyanoacrylate (superglue fuming)

• reacts with amino acids, proteins, and fatty acid residues

Fluorescence of Fingerprints• Fingerprint residues contain substances

that will fluoresce when exposed to certain wavelengths of light

• After cyanoacrylate fuming is done, Rhodamine 6G, which is a dye, was applied. This fluoresces and emits yellow light

• Argon laser aimed at print and photo is taken using a special filter

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Powders• Powders can be applied with a brush or magnetic

wand

• When applied lightly to a nonabsorbent surface adhere to perspiration residues and/or deposits of body oils left on the surface.

• Powders come in different colors, are magnetic- sensitive, or are fluorescent to aid the investigator.

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Preservation of a Developed Print

• Once the latent print has been visualized, it must be permanently preserved for future comparison and for possible use as court evidence.

• A photograph must be taken before any further attempts at preservation are made.

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Transporting Prints

• 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.

Comparison of Prints

• Crime scene prints compared to known prints

• Ten print card: used to collect fingerprints

• Rolled print: fingerprint rolled from cuticle to cuticle

• Tap prints: fingerprints that are tapped in ink and then placed at bottom of ten print card

Digital Fingerprinting

• Live Scan: 1990’s• replaces inked ten print card• captures friction ridge image and stores

digitally in computer database

• Umbrella group of fingerprint experts• Decided in 1990 no standard minimum number of

points would be necessary for positive identification

• Three level of friction ridge details would be used to identify prints

International Association for Identification

Levels of Friction Ridge Details• Level 1

• general features and patterns• can be used to exclude a print only

• Level 2• includes particular ridges (minutiae) in same place that

allow individualization of an unknown print• Level 3

• requires low power microscope• identifies minute imperfections, such as scars, edge shapes,

sweat gland pores• so unique their presence virtually assures individuality

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