FINGERPRINTS

FINGERPRINTS

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Chapter 14

Students Will Be Able To:

• Describe the formation of a fingerprint.• Discuss the history of fingerprinting.

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“Today the fingerprint is the pillar of modern criminal identification.”

Dactylscopy

• Is the study of fingerprints

Principles of Fingerprints

• Is an individual characteristic• Will remain unchanged during an

individual’s lifetime• Have general characteristic ridge

patterns that permit them to be classified

History of Fingerprinting

• Earliest records of using fingerprints date back to 1792-1750 BC in Babylon• Used to bind contracts

• In China, fingerprints were used on contracts and loans

• In 1788 Johann Christoph Andreas Mayer stated that no two people had the same ridge pattern

• In 1823, Jan Purkyn described 9 distinct fingerprint patterns• Loops• Spirals• Circles• Double whorls

The History of Fingerprinting

• Throughout history, there are six significant people involved in fingerprinting• William Herschel• Henry Faulds• Alphonse Bertillion• Francis Galton• Edward Richard Henry• Juan Vucetich

William Herschel

• Began collecting fingerprints in 1856• Said that patterns were unique to each

person and were not altered by age• Required natives to sign contracts with

imprint of right hand

Henry Faulds

• Suggested that skin ridge patterns could be important for the identification of criminals

Alphonse Bertillion

• Proposed body measurements as a means of identification• Field called anthropometry

• System called for 11 measurements to be taken• Height, reach, width of head, length of

each food are a few examples• Identification via anthropometry was

replaced with fingerprints• No two people can have the same

fingerprints; however, 2 people can have the same anthropometric measurements

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Francis Galton

• Verified that fingerprints do not change with age

• Developed a primary classification scheme based on loops, whorls, and arches

• Wrote a book called Finger Prints• States that a person’s fingerprints do

not change over the years• His system was adopted by the British

government• Was the first person credited with solving a

murder using fingerprints

Edward Richard Henry

• Worked with Galton to institute a numerical classification system to file fingerprints

• English speaking countries including the US use Henry’s classification system

• Also Devised the ten print card• All fingers are

fingerprinted

Juan Vucetich

• Developed a fingerprint classification based on Galton’s that is used in Spanish speaking countries

History Clip

Fingerprints

• Fingerprints are a reproduction of friction skin ridges found on the palm side of the fingers and thumbs• Also found on the surface of the palms

and the soles of the feet• Provide our bodies with a firm grasp and

resistance to slippage

Fingerprints

• Form in utero beginning at the 10th week of pregnancy

• Creation happens in the basal layer of the epidermis• Skin cells grow more rapidly here than

the epidermis on the outside and the dermis on the inside

• Basal layer ends up collapsing and folding in different directions

Skin

• Is composed of layers of cells• 2 main portions exist

• Epidermis• Outer portion of the skin

• Dermis • Inner portion of the skin

• Dermal papillae separate the 2 portions• Shape of the boundary determines the

form and pattern of the ridges

Skin

• Each skin ridge has a row of pores • Are openings for ducts leading from the

sweat gland• Perspiration and oils pass through

these ducts• Is left behind when an object has

been touched• This is the fingerprint

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Where Do Fingerprints Come From Video Clip

Students Will Be Able To:

• Describe the characteristics of fingerprints.• Identify the basic types of fingerprints.

Characteristics of Fingerprints

• Two things a forensic examiner look for on a fingerprint are• Presence of a core

• Is the center of the loop or whorl• Presence of a delta

• Is a triangular region located near a loop

• Also use a ridge count• Is the area from the delta to the core

Pattern Characteristics

• All fingerprints are divided into three classes based on their pattern• Loops• Whorls• Arches

Loops

• Must have one or more ridges entering and exiting from the same side

• Must have one delta• 2 types

• Radial- opens toward the thumb• Ulnar- opens toward the pinky

• Occurs in 60-65% of the population

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.

DeltaUlnar Loop (Right Hand)

Loop opens toward the little finger (or ulna).

Radial Loop (Right Hand)Loop opens toward the thumb (or radius).

Delta

Whorls

• Must have a type line, a core, and a minimum of 2 deltas

• Divided into 4 groups• Plain- have at least one ridge that

makes a complete circuit• Central pocket loop- have at least one

ridge that makes a complete circuit• Double loop- made up of 2 loops

combined into one fingerprint• Accidental- contains 2 or more patterns

or is a pattern covered by the other categories

• Occur in 30-35% of the population

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 WhorlCentral 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

Arches

• Has friction ridges that enter on one side of the finger and cross to the other side while rising upward in the middle

• Do not have type lines, deltas, or cores

• 2 types• Plain- normal wavelike pattern• Tented- is the same as plain except that

a sharp spike occurs at the center• Occur in 5% of the population

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 ArchesSimilar to the plain arch,

but has a spike in the center.

Spike or “tent”

Your Turn

Ridge Characteristics

• Must match in two fingerprints in order for their common origin to be established

• No set limit on how many minutiae must match has been set• However, courts

will accept 8-12 points of similarity

• Also known as minutiae

• Includes• Ridge ending• Short ridge• Dot or fragment• Bifurcation• Double bifurcation• Trifurcation• Bridge• Island• Enclosure• Spur

Students Will Be Able To:

• Identify the importance of the Henry classification system for fingerprints.

• Calculate the classification number of an individual with certain whorl patterns.

Primary Classification

• The Henry- FBI classification system

Primary Classification

• It will provide the fingerprint examiner with a number of candidates

• System is only useful in cases when a full set of fingerprints is available

Primary Classification

• Each finger is assigned a number of points if a whorl is present

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

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

=

Primary Classification• The lowest primary classification a person can have is

1/1

0 + 0 + 0 + 0 + 0 + 1 = 1

0 + 0 + 0 + 0 + 0 + 1 1

If an individual has the lowest possible classification, you would immediately know that the person has loops or arches on all ten fingers and no whorls

• The highest possible classification a person can have is 32/32

16 + 8 + 4 + 2 + 1 + 1 = 32

16 + 8 + 4 + 2 + 1 + 1 32

If an individual has the highest possible classification, you would immediately know that the person has whorls on all ten fingers

Students Will Be Able To:

• Distinguish among visible, plastic, and latent fingerprints.

• Explain how fingerprint evidence is collected.

• List the techniques for developing latent fingerprints on porous and nonporous objects.

• Describe the proper procedures for preserving a developed latent fingerprint.

Types of Prints

• 3 types• Visible • Plastic • Latent

Visible Prints

• Prints made when fingers touch a surface after the ridges have been in contact with a colored material such as blood, paint, grease, or ink

Plastic Prints

• Prints made by ridge impressions left on a soft material such as putty, wax, soap, or dust

Latent Prints

• Prints that are not visible to the naked eye• Consist of the natural secretions of human

skin and require development for them to become visible

• 3 types of secretions• Eccrine- water, inorganic and organic

compounds• Sebaceous- secrete fatty or greasy substances• Apocrine- secrete pheromones and other

organic materials

Developing Prints

• Requires substances that interact with secretions that cause the print to stand out against its background

• May be necessary to attempt more than one technique• Start with the least destructive method

Developing Prints

• 5 ways to develop• Powders• Iodine• Ninhydrin• Silver nitrate• Cyanoacrylate

Powders

• Adhere to water and fatty deposits• Color dependent on background

• White or gray for dark surfaces• Black for light surfaces

Iodine Fuming

• Involves heating iodine crystals that cause vapors which combine with latent prints to make them visible

• Prints are not permanent and will fade• Necessary to photograph the prints

Ninhydrin

• Reacts chemically with trace amounts of amino acids present in latent prints to produce a purple- blue color

• Is the preferred method

Silver Nitrate

• Reacts with chloride to form silver chloride, a material which turns gray when exposed to light

Cyanoacrylate

• Is super glue• Fumes react

with water and other fingerprint constituents to form a hard, whitish deposit

Transporting Prints

• If small, preserve entirely • If big, dust and then lift the prints with a

broad adhesive tape• Tape is placed on a properly labeled

card

Behind the Badge- CSU Fingerprints

Students Will Be Able To:

• List and describe the importance of tire prints, shoe prints, lip prints, retinal scans, teeth marks, etc.

• Describe the concept of an automated fingerprint identification system (AFIS) .

Other Prints

• Ears- shape, length, and width• Voice- electronic pulses measured with a

spectrograph

Other Prints

• Shoes • Can be

compared and identified by type of shoe, brand, size, year of purchase, and wear pattern

Other Prints

• Foot• Size of foot and

toes, friction ridges on the foot

Other Prints

• Palm• Friction ridges

can be identified and may be used against suspects

Other Prints

• Lips• Display several

common patterns• Short vertical

lines• Short

horizontal lines• Crosshatching• Branching

grooves

Other Prints

• Teeth• Bite marks are

unique and can be used to identify suspects

Other Prints

• Retinal • Blood vessels

in the eye may be unique to individuals

Other Prints

• Tire prints• Can identify

vehicles

AFIS

• By the 1990s, most large jurisdictions had their own system in place• A problem exists when 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 data of all 10-print cards from all over the country

AFIS

• Stands for Automated Fingerprint Identification System

• Is a computer system for storing and retrieving fingerprints

• Began in the early 1970s 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

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