1. Chapter 4: Fingerprints
“Fingerprints can not lie,
but liars can make fingerprints.”
—Unknown

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Fingerprints
You will learn:
Why fingerprints are individual evidence.
Why there may be no fingerprint evidence at a crime scene.
How computers have made personal identification easier.
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Fingerprints
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.
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Fingerprints
Recording Prints – kept for comparison
rolling inked prints
primary identification number
FBI has national database called AFIS
Lifting Prints – retrieved from the scene
Black, white and fluorescent powder
Chemicals—ninhydrin, iodine, silver nitrate, cyanoacrylate
Other Types of Prints – can be individual too!
What are some other types?
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Fingerprints
Interesting Stuff
Fingerprints begin to develop in the 6th week of gestation inside the womb
Fingerprints go from the epidermis (top layer) to the dermis (under layer)
Epidermis
Dermis
Fingerprints grow back and are very hard to destroy…however not impossible!
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Fingerprints
John Dillinger – Public Enemy # 1 in the 1930’s
Paid a doctor $5000 plus $25 room and board to dissolve his fingerprints and perform some minor surgery on his face…
Although the center of his fingerprints became obscure there was plenty of minutiae around the edges to identify him.
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7. Dactyloscopy The study of fingerprints
Historically
Alphonse Bertillon—proposed body measurements as a means of identification; termed anthropometry …he believed no two people are alike…devised a measurement system of people…and until the William West and Will West case in 1903 it was a good method
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8. Dactyloscopy The study of fingerprints
Historically
1890’s - Francis Galton—developed a primary classification scheme based on loops, arches and whorls.
1890’s - Juan Vucetich—developed a fingerprint classification based on Galton’s that is used in Spanish-speaking countries
1901 – Sir Edward Richard Henry—in collaboration with Galton instituted a numerical classification system… The 10 print classification system…this system is still used today!
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9. Dactyloscopy The study of fingerprints
Historically
Adopted Fingerprints as Main ID System
1904 – US Penitentiary System (Will and William West Case)
1905 – US Army
1907 – US Navy
1908 – US Marine Corp.
1924 – FBI Established – currently over 200 million cards
1980 – AFIS introduced – Automated Fingerprint Identification System
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10. Fundamental Principles of Fingerprints
A fingerprint unique and is an individual characteristic.
A fingerprint will remain unchanged during an individual’s lifetime.
Fingerprints have general characteristic ridge patterns that permit them to be systematically classified.
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11. 3 Basic Patterns of Fingerprints
Arch
Loop
Whorl 5%
65%
30%
Population Breakdown by %
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Arch
Plain 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
Exit here
Enter here
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Arch
Plain Arch
Tented Arch
Arch not as high
Arch higher in center
pp. 53 in your book
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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?
Enter and exit from this side
Delta
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Loop
Opens toward thumb
Opens toward pinky
pp. 52 in your book
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Whorl
Core
Whorls have at least two deltas and a core.
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.
Types
Plain
Central Pocket
Double Loop
Accidental
Two Deltas
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17. Whorl whorls have at least two deltas and a core.
pp. 53 in your book
A plain or central pocket whorl has at least one ridge that makes a complete circuit.
An accidental is a pattern not covered by other
categories.
A double loop is made of two loops.
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18. Ridge Characteristics
Minutiae—characteristics of ridge patterns
Ridge ending
Short ridge
Dot or fragment
Bifurcation
Double bifurcation
Trifurcation
Bridge
Island
Enclosure
Spur
pp. 57 in your book
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Fingerprint Minutiae
pp. 57 in your book
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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.
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21. Primary Classification
The Henry—FBI Classification
Each finger is given a point value
right
left
Allows all fingerprints to be classified into only 1024 categories
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22. Primary Classification
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 =
Left
right right right left left
thumb middle little index ring
That number is your primary classification number
Right
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23. Primary Classification
The Henry—FBI Classification
Each finger is given a point value
Only two of my fingers have whorls…so I assign values 2 1
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24. Primary Classification
Mr. Stoudnour’s Primary Classification is
right right left left left
index ring thumb middle little 1
______ = 4
right right right left left
thumb middle little index ring
This is one of the 1024 categories…Who else in this room is in Mr. S’s category?
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Types of Prints
Plastic prints – indented or molded prints – made from pressing a finger into a plastic-like material to form a negative impression.
Visible prints – left by a finger that has touched a colored surface such as blood, paint, ink, grease, mud or dust.
Latent prints – invisible prints that must be developed by chemical or physical means.
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Plastic Prints
Indented or molded prints – made from pressing a finger into a plastic-like material to form a negative impression.
Take pictures of the print
Recover the whole item the print is on and send to lab
Enlarge the picture
This is silly putty
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Visible Prints
left by a finger that has touched a colored surface such as blood, paint, ink, grease, mud or dust.
Take pictures of the print
Lift the print (these could be impossible to lift)
Recover the whole item the print is on and send to lab
These are sharpie marker prints
Enlarge the picture
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Latent Prints
Invisible prints that must be developed by chemical or physical means.
Use a dusting powder or chemical means to develop the print
Take pictures of print
Lift the print when possible
If you can’t lift the print…Recover the whole item the print is on and send to lab
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Latent Prints
The reason you get these prints is because you secrete different substances from your skin.
Most secretions come from three glands:
Eccrine (Sweat)—largely water, salts and amino acids (protein)
Apocrine—secrete pheromones and other organic materials.
Sebaceous—secrete fatty or greasy substances.
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30. Developing Latent Prints
Developing a print requires substances that interact with secretions that cause the print to stand out against its background.
Different types of surfaces (porous or non- porous) dictate what method of print development is to be used.
It may be necessary to attempt more than one technique, done in a particular order so as not to destroy the print.
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 Since lasers can damage the retina of the eye, special precautions must be taken.
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31. Developing Latent Prints
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.
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Partial Prints
You do not need to lift a complete fingerprint to have sufficient ridge detail (minutia) present for an identification.
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Documenting Prints
Lift the print and put it on an index card
Case Number
Victim Information
Incident Location
Incident Date
Recovering Officer Name
Object or Location of Recovered Lift
Method of Development
Orientation if Needed
Diagram where you found it
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Put all pertinent information on the card

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Documenting Prints
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Iodine Fingerprint
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36. Ninhydrin Fingerprint
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37. Cyanoacrylate Fingerprints
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Other Prints
Ears—shape, length and width
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
Palm—friction ridges can be identified and may be used against suspects.
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Other Prints
Footprints are taken at birth as a means of identification of infants.
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Other Prints
Lips—display several common patterns
Short vertical lines
Short horizontal lines
Crosshatching
Branching grooves
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Other Prints
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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Other Prints
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
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.
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More about Prints
For additional information about prints and crime, check out Court TV’s Crime Library
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