1. Chapter 6 Fingerprints By the end of this chapter you will be able to:
discuss the history of fingerprinting
describe the characteristics of fingerprints and fingerprinting minutiae
explain when and how fingerprints are formed
describe what causes fingerprints to be left on objects
identify the basic types of fingerprints
describe how criminals attempt to alter their fingerprints
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Forensic Science: Fundamentals & Investigations, Chapter 6

2. Chapter 6 Fingerprints By the end of this chapter you will be able to:
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

3. Historical Development
The oldest known documents showing fingerprints date from third century B.C. China.
In ancient Babylon (dating back to B.C.), fingerprints pressed into clay tablets marked contracts.
The earliest written study (1684) is Dr. Nehemiah’s paper describing the patterns he saw on human hands under a microscope, including the presence of ridges.
In 1788, Johann Mayer noted that the arrangement of skin ridges is never duplicated in two persons. He was probably the first scientist to recognize this fact.
Forensic Science: Fundamentals & Investigations, Chapter 6

4. Historical Development
5. Nine fingerprint patterns were described in by Jan Evangelist Purkyn.
6. Sir William Herschel (shown at the right), in 1856, began the collection of fingerprints and noted they were not altered by age.
Alphonse Bertillon created a way to identify criminals that was used in 1883 to identify a repeat offender.
In 1902, he was credited with solving the first murder using fingerprints.
8. In 1888, Sir Francis Galton (shown at the right), and Sir Edmund Richard Henry, developed the fingerprint classification system that is still in use in the United States.
Forensic Science: Fundamentals & Investigations, Chapter 6

5. Historical Development
9. In 1891, Iván (Juan) Vucetich improved fingerprint collection. He began to note measurements on identification cards, as well as adding all ten fingerprint impressions. He also invented a better way of collecting the impressions.
10. Beginning in 1896, Sir Henry (mentioned in the last entry on the previous slide), with the help of two colleagues, created a system that divided fingerprints into groups based on whether they had an arch, loop, or whorl pattern. Along with notations about individual characteristics, all ten fingerprints were imprinted on a card (called a ten card).
Forensic Science: Fundamentals & Investigations, Chapter 6

6. What Are Fingerprints?
All fingers, toes, feet, and palms are covered in small ridges.
These ridges are arranged in connected units called dermal, or friction ridges. These ridges help us get or keep our grip on objects.
Natural secretions plus dirt on these surfaces leave behind an impression (a print) on those objects with which we come in contact.
Natural secretions from the sweat glad in the friction ridge of the skin are a combination of mainly water, oils, and salts.
Dirt from everyday activities also mixes into the secretions.
Anytime you touch something you leave behind traces of these substances in the unique pattern of your dermal ridges.

7. Sweat Pore
Forensic Science: Fundamentals & Investigations, Chapter 6

8. Formation of Fingerprints
An animal’s external tissue (skin) consists of (a) an inner dermis and (b) an outer epidermis.
The creation of fingerprints occurs in a special layer (the basal layer) in the epidermis where new skin cells are produced.
Fingerprints probably begin forming at the start of the 10th week of pregnancy.
Because the basal layer grows faster than the others, it collapses, forming intricate shapes.
Forensic Science: Fundamentals & Investigations, Chapter 6

9. Formation of Fingerprints
Patterns are probably formed the during the 10th week of pregnancy along with prints of the palms of the hands, soles of the feet, and lip prints.
The creations of fingerprints happens in the basal layer, a specialized area within the epidermis where new skin cells are produced.
In a fetus, this layer grows faster than the epidermis (outside) and dermis (inside) thus the layer collapses and folds in different directions creating intricate shapes between the other layers of skin.
The pattern cannot be altered or destroyed permanently by skin injuries because the outer layer protects it.

10. Characteristics of Fingerprints
There are 3 general fingerprint distinctions:
ARCH WHORL LOOP
About 5% About 30% About 65% of the population
Forensic Science: Fundamentals & Investigations, Chapter 6

11. Loop Whorl Arch

12. Characteristics of Fingerprints
Named for their general visual appearance and patterns.
Called loops, whorls, and arches.
Arches(5% of the population has this type):
have ridges that enter from one side of the fingerprint and leave from the other side with a rise in the center.
Whorls (30% of the population has this type):
Look like a bull’s-eye with two deltas (triangles).
Loops (65 % of the population has this type):
Enter from either the right or the left and exit from the same side they enter.

13. Characteristics of Fingerprints
Basic patterns can be further divided:
Arch patterns can be plain (4%) or tented (1%).
Whorl patterns can be a plain whorl (24%) a central pocket loop whorl (2%), double loop whorl (4%), or accidental (0.01%).
Even twins have unique fingerprints due to small differences (called minutiae) in the ridge patterns.
Forensic Science: Fundamentals & Investigations, Chapter 6

14. Characteristics of Fingerprints*
Forensic Science: Fundamentals & Investigations, Chapter 6

15. Whorls Basic patterns can be further divided: .
Whorl patterns can be a plain whorl (24%) a central pocket loop whorl (2%), double loop whorl (4%), or accidental (0.01%). .

16. Whorls (cont.)
The plain whorl has one or more ridges that make a complete spiral. There are two deltas, and if a line is drawn between them, at least one ridge in the inner pattern is touched or cut by the line.
The central pocket loop whorl has one or more ridges that make a complete circle. There are two deltas, and if a line is drawn between them, no ridges in the inner pattern are touched or cut by the line.
The double loop whorl has two separate loop formations and two deltas.
The accidental whorl has two or more deltas and is a combination of two of the other patterns (but not a plain arch).

17. Arches Arches can be further divided:
Plain arches (4%) and tented arches (1%).
The plain arch shows ridges entering one side, rising in the center, and flowing out the other side without making an angle.
The plain arch has no characteristics of the loop pattern.
The tented arch does form an angle, or it may possess some characteristic of the loop pattern, such as a delta.

18. Characteristics of Fingerprints*
Forensic Science: Fundamentals & Investigations, Chapter 6

19. Arches (cont.)

20. Characteristics of Fingerprints
Forensic examiners look for
Core (the center of a whorl or loop)
Deltas (triangular regions near a loop)
Ridge count
Counting from the core to the edge of the delta
Distinguishes one fingerprint from another *
Forensic Science: Fundamentals & Investigations, Chapter 6

21. To take a ridge count, an imaginary line is drawn from the center of the core to the edge of the delta.

22. Example of a Ten Card *
Forensic Science: Fundamentals & Investigations, Chapter 6

23. Characteristics of Fingerprints (cont.)
Every individual, including identical twins, has a unique fingerprint resulting from unique ridge patterns called minutiae.
There are about 150 individual ridge characteristics on the average full fingerprint.
To match fingerprints, a minimum number of points of comparison are needed. (12-18 points needed)
Forensic Science: Fundamentals & Investigations, Chapter 6

24. Pictures of minutiae
Forensic Science: Fundamentals & Investigations, Chapter 6

25. See page 139 for more examples of minutiae patterns

26. Types of Fingerprints
There are 3 types of prints that investigators look for at crime scenes:
Patent fingerprints are visible prints transferred onto smooth surfaces by blood or other liquids.
Plastic fingerprints are indentations left in soft materials such as clay, putty, or wax.
Latent fingerprints, or hidden prints, are caused by the transfer of oils and other body secretions onto a surface. They can be made visible by dusting with powders or the use of chemicals.

27. Fingerprint Forensic FAQs
Can fingerprints be erased?
No, if, for example, they are removed with chemicals, they will grow back.
Is fingerprint identification reliable?
Yes, but analysts can make mistakes.
Is fingerprint matching carried out by computers in a matter of seconds?
No, but the FBI’s Integrated Automated Fingerprint Identification System (IAFIS or AFIS) can provide a match in 2 hours for the prints in its Master File.
Forensic Science: Fundamentals & Investigations, Chapter 6

28. Fingerprint Forensic FAQs
How are latent fingerprints collected?
Forensic Science: Fundamentals & Investigations, Chapter 6

29. How Are Fingerprints Analyzed?
By 1987, the FBI had 23 million criminal fingerprint cards on file. Finding a match sometimes took up to 3 months.
In 1999, with cooperation of the national law enforcement community, the FBI developed the Integrated Automated Fingerprint Identification System (AFIS). Linked with authorities globally it became IAFIS.
IAFIS provides digital, automated fingerprint searches, latent searches, and electronic exchange of fingerprints and test results.

30. The Future of Fingerprinting
New scanning technologies and digitally identifying patterns may eliminate analytical mistakes.
Trace elements of objects that have been touched are being studied to help with the identification of individuals.
To help with identification, other physical features such as eyes and facial patterns are also being studied.
Forensic Science: Fundamentals & Investigations, Chapter 6

31. The Future of Fingerprinting
New scanning technologies
Yield detail in minute patterns
Reduce analytical mistakes
Analyze trace elements of objects on the skin
To help with identification, other physical features such as eyes and facial patterns are also being studied.
Retina
Face
Veins in your palm *
Forensic Science: Fundamentals & Investigations, Chapter 6

32. Summary
Fingerprints have long been used for identification, and in the mid-1800s were recognized as unique to each person.
Three main groups include arches, whorls, and loops.
Basic analysis includes looking for cores, deltas, and making a ridge count.
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