Chapter 6 Fingerprints By the end of this chapter you will be able to: o o o Discuss the history of fingerprinting Describe the characteristics of fingerprints and fingerprinting minutiae Explain when and how fingerprints form Describe how fingerprints can be left on objects Identify the basic types of fingerprints Describe how criminals attempt to alter their fingerprints All Rights Reserved South-Western / Cengage Learning © 2012, 2009 1 Forensic Science: Fundamentals & Investigations, Chapter 6
Chapter 6 Fingerprints By the end of this chapter you will be able to: o o o 2 Determine the reliability of fingerprints as a means of identification Describe the Integrated Automated Fingerprint Identification System (IFAIS) Explain how fingerprint evidence is collected Describe the latest identification technologies Determine if a fingerprint matches a fingerprint on record Use the process of lifting a latent print Forensic Science: Fundamentals & Investigations, Chapter 6
Historical Development 1. 2. Ancient Babylon (1792 -1750 B. C. )—fingerprints pressed into clay tablets marked contracts 3. 1684—Dr. Nehemiah’s paper describes the patterns on human hands, including the presence of ridges 4. 3 3 rd century B. C. in China—oldest known documents 1788—Johann Mayer noted that the arrangement of skin ridges is never duplicated in two persons Forensic Science: Fundamentals & Investigations, Chapter 6
Historical Development 5. 6. 7. 4 1823—Jan Evangelist Purkyn describes nine fingerprint patterns 1856—Sir William Herschel (right) began the collection of fingerprints and noted they were not altered by age 1883—Alphonse Bertillon created a way to identify criminals that were repeat offenders Forensic Science: Fundamentals & Investigations, Chapter 6
Historical Development 8. 9. 10. 5 1888—Sir Francis Galton (r) and Sir Edmund Richard Henry developed the fingerprint classification system still used in the US 1891—Iván (Juan) Vucetich collected all ten fingerprint impressions and noted measurements 1896—Sir Henry, with two colleagues, created a system that divided fingerprints into groups. All ten fingerprints are imprinted on a card (called a ten card) along with other notations Forensic Science: Fundamentals & Investigations, Chapter 6
Example of a Ten Card 6 Forensic Science: Fundamentals & Investigations, Chapter 6
What Are Fingerprints? o o o 7 All fingers, toes, feet, and palms are covered in small ridges Ridges help us grip objects Ridges are arranged in connected units called dermal, or friction, ridges Fingers accumulate natural secretions and dirt Fingers leave create prints on objects we touch Forensic Science: Fundamentals & Investigations, Chapter 6
Structure of Skin 8 Forensic Science: Fundamentals & Investigations, Chapter 6
Formation of Fingerprints o Skin consists of: • • • o o o 9 Inner layer—dermis Outer layer—epidermis Dermal Papillae - Basal layer in between Basal layer grows faster than the layers above and below it Basal layer collapses and folds to form intricate shapes Fingerprints begin forming near the 10 th week of pregnancy Forensic Science: Fundamentals & Investigations, Chapter 6
Characteristics of Fingerprints o There are 3 general fingerprint distinctions: ARCH WHORL LOOP About 5% About 30% About 65% of the population 11 Forensic Science: Fundamentals & Investigations, Chapter 6
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Characteristics of Fingerprints o Forensic examiners look for • • o Ridge count • • 13 Core (the center of a whorl or loop) Deltas (triangular regions near a loop) Counting from the core to the edge of the delta Distinguishes one fingerprint from another Forensic Science: Fundamentals & Investigations, Chapter 6
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Loops o A loop must have one or more ridges entering from one side of the print, recurving, and exiting from the same side. • • 15 If the loop opens toward the little finger, it is called an ulnar loop. If the loop opens toward the thumb, it is called a radial loop. Forensic Science: Fundamentals & Investigations, Chapter 6
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Whorls o o 17 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. Forensic Science: Fundamentals & Investigations, Chapter 6
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Characteristics of Fingerprints 19 Forensic Science: Fundamentals & Investigations, Chapter 6
Arches o o Least common of the three types Divided into 2 categories • • 20 Plain Arch Tented Arch Forensic Science: Fundamentals & Investigations, Chapter 6
Characteristics of Fingerprints 21 Forensic Science: Fundamentals & Investigations, Chapter 6
Characteristics of Fingerprints o Basic patterns can be further divided: • Arch patterns: • 4% plain • 1% tented • Whorl patterns: • 2% central pocket • 4% double loop • 0. 01% accidental o 22 Even twins have unique fingerprints Forensic Science: Fundamentals & Investigations, Chapter 6
Fingerprint Minutiae Patterns 23 Forensic Science: Fundamentals & Investigations, Chapter 6
Primary Classification o o 24 Fingerprint classification systems are based on knowledge of fingerprint pattern classes. First, fingers are paired up, placing one finger in the numerator of a fraction and the other in the denominator. Forensic Science: Fundamentals & Investigations, Chapter 6
Fraction Set Up R Index R Ring L Thumb L Middle L Little R Thumb R Middle R Little L Index L Ring 25 Forensic Science: Fundamentals & Investigations, Chapter 6
Classification cont… o 26 The presence or absence of the whorl pattern is the basis for the determination of the primary classification. Forensic Science: Fundamentals & Investigations, Chapter 6
Classification Cont… o o 27 If a whorl pattern is found on any finger of the first pair, it is assigned a value of 16; on the second pair, an 8; on the third pair, a 4; on the fourth pair, a 2; and on the last pair, a 1. Any finger having a loop or arch is assigned a 0. Forensic Science: Fundamentals & Investigations, Chapter 6
o o 28 After values for all 10 fingers are obtained, they are totaled, and a 1 is added to both the numerator and denominator. The fraction thus obtained is the primary classification. Forensic Science: Fundamentals & Investigations, Chapter 6
o 29 Approximately 25% of the population falls into the 1/1 category; that is, all their fingers have either loops or arches. Forensic Science: Fundamentals & Investigations, Chapter 6
Practice o 30 An individual has a whorl on the right Thumb, Right Index, Right Pinky, and Left Middle. How would this individual be classified? Forensic Science: Fundamentals & Investigations, Chapter 6
Types of Fingerprints There are 3 types of prints that investigators look for at crime scenes: 1. Visible fingerprints—visible prints transferred onto smooth surfaces by blood or other liquids 2. Patent fingerprints—indentations left in soft materials such as clay or wax 3. Latent fingerprints—made visible by dusting with powders or the use of chemicals 31 Forensic Science: Fundamentals & Investigations, Chapter 6
Fingerprint Forensic FAQs o 32 How are latent fingerprints collected? Forensic Science: Fundamentals & Investigations, Chapter 6
AFIS – Automated Fingerprint Identification System o 33 The heart of AFIS technology is the ability of a computer to scan and digitally encode fingerprints so that they can be subject to high-speed computer processing. Forensic Science: Fundamentals & Investigations, Chapter 6
Fingerprint Forensic FAQs o Can fingerprints be erased? Only temporarily; they will grow back if removed with chemicals o Is fingerprint identification reliable? Yes, but analysts can make mistakes o Can computers perform matches in seconds? No, but the FBI’s Integrated Automated Fingerprint Identification System (IAFIS or AFIS) can provide a match in 2 hours 34 Forensic Science: Fundamentals & Investigations, Chapter 6
The Future of Fingerprinting o New scanning technologies • • • o Technologies that recognize patterns in • • • 35 Yield detail in minute patterns Reduce analytical mistakes Analyze trace elements of objects on the skin Retina Face Veins in your palm Forensic Science: Fundamentals & Investigations, Chapter 6
Preserving Prints o o 36 If small enough – take whole item, take care so print is not damaged during transport A photograph must be taken before any attempts at preservation are made. Forensic Science: Fundamentals & Investigations, Chapter 6
Preserving Prints o If large item can “lift” print using broad adhesive tape Tape placed on appropriately labeled card o Must photograph all prints and surroundings. o 37 Forensic Science: Fundamentals & Investigations, Chapter 6
. . . Summary. . o o o 38 Fingerprints have long been used for identification, and in the mid-1800 s were recognized as unique to each person. Three main groups include arches, whorls, and loops. Basic analysis includes looking for cores and deltas and making a ridge count. Forensic Science: Fundamentals & Investigations, Chapter 6
. . . . Summary o o o 39 Investigators search for patent, plastic, and latent prints. Dusting with powders or using special chemicals can make latent fingerprints visible. New developments may eliminate errors by analysts. Forensic Science: Fundamentals & Investigations, Chapter 6
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