Forensic Science: Fundamentals & Investigations, Chapter 6 1 Chapter 6 Fingerprints By the end of this chapter you will be able to: o Discuss the history of fingerprinting o Describe the characteristics of fingerprints and fingerprinting minutiae o Explain when and how fingerprints form o Describe how fingerprints can be left on objects o Identify the basic types of fingerprints o Describe how criminals attempt to alter their fingerprints All Rights Reserved South-Western / Cengage Learning © 2012, 2009

Forensic Science: Fundamentals & Investigations, Chapter 6 2 Chapter 6 Fingerprints By the end of this chapter you will be able to: o Determine the reliability of fingerprints as a means of identification o Describe the Integrated Automated Fingerprint Identification System (IFAIS) o Explain how fingerprint evidence is collected o Describe the latest identification technologies o Determine if a fingerprint matches a fingerprint on record o Use the process of lifting a latent print

Forensic Science: Fundamentals & Investigations, Chapter 6 3 Historical Development 1. 3rd century B.C. in China—oldest known documents 2. Ancient Babylon ( B.C.)—fingerprints pressed into clay tablets marked contracts —Dr. Nehemiah’s paper describes the patterns on human hands, including the presence of ridges —Johann Mayer noted that the arrangement of skin ridges is never duplicated in two persons

Forensic Science: Fundamentals & Investigations, Chapter 6 4 Historical Development —Jan Evangelist Purkyn describes nine fingerprint patterns —Sir William Herschel (right) began the collection of fingerprints and noted they were not altered by age —Alphonse Bertillon created a way to identify criminals that were repeat offenders

Forensic Science: Fundamentals & Investigations, Chapter 6 5 Historical Development —Sir Francis Galton (r) and Sir Edmund Richard Henry developed the fingerprint classification system still used in the US —Iván (Juan) Vucetich collected all ten fingerprint impressions and noted measurements —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 6 Example of a Ten Card

Forensic Science: Fundamentals & Investigations, Chapter 6 7 What Are Fingerprints? o All fingers, toes, feet, and palms are covered in small ridges o Ridges help us grip objects o Ridges are arranged in connected units called dermal, or friction, ridges o The imprint of a fingerprint consists of natural secretions of the sweat glands (pores) that are present in the friction ridges of the skin.

What are fingerprints? (continued) o The secretions are a combination of water, oils, and salts. Dirt also gets mixed into the secretions. o Anytime you touch something, you leave behind traces of these substances in the unique pattern of your friction ridges.

Forensic Science: Fundamentals & Investigations, Chapter 6 9 Structure of Skin

Forensic Science: Fundamentals & Investigations, Chapter 6 10 Formation of Fingerprints o Skin consists of: Inner layer—dermis Outer layer—epidermis Basal layer in between where new skins cells are produced o In a fetus, the basal layer grows faster than the layers above and below it (dermis & epidermis). o Because it grows faster, the basal layer collapses and folds in different directions to form intricate shapes. o Fingerprints begin forming near the 10 th week of pregnancy when the fetus is about 3 inches long!

Arches have no deltas Whorls have 2 deltas Loops have 1 delta 11 Characteristics of Fingerprints o There are 3 general fingerprint distinctions:

Forensic Science: Fundamentals & Investigations, Chapter 6 12 Characteristics of Fingerprints o 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

Has 1 or more ridges that make a complete circle Has 2 separate loop formations. Has 2 or more deltas and is a There are 2 deltas There are 2 deltas combination of other patterns. 13 Characteristics of Fingerprints

Ridges enter 1 side, rise in the center, and flow out the other Does form an angle, or it may possess some characteristic side without making an angle. of the loop pattern, such as a delta. 14 Characteristics of Fingerprints

Forensic Science: Fundamentals & Investigations, Chapter 6 15 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 Even twins have unique fingerprints

Characteristics of Fingerprints o Looking at basic fingerprint patterns can quickly help eliminate a suspect. o In order to positively match a print found at a crime scene to an individual, more information is needed. Every individual has a unique fingerprint resulting from unique ridge patterns called minutiae (because the details are so small). Recognizing these details in the differences between ridges, their relative number, and their location on a specific fingerprint is called fingerprint identification.

(continued) There are about 150 individual ridge characteristics on the average full fingerprint. When forensic examiners identify a fingerprint, they are in theory identifying the unique signature of a person, and they can be pretty sure they are characterizing only one particular individual in the world. To match fingerprints, a minimum number of points of comparison is needed.

Forensic Science: Fundamentals & Investigations, Chapter 6 18 Fingerprint Minutiae Patterns

Forensic Science: Fundamentals & Investigations, Chapter 6 19 Types of Fingerprints There are 3 types of prints that investigators look for at crime scenes: 1. Patent fingerprints—visible prints transferred onto smooth surfaces by blood or other liquids 2. Plastic fingerprints—indentations left in soft materials such as clay, putty, or wax 3. Latent fingerprints (hidden prints)—made visible by dusting with powders or the use of chemicals

Forensic Science: Fundamentals & Investigations, Chapter 6 20 Fingerprint Forensic FAQs o How are latent fingerprints collected?

Forensic Science: Fundamentals & Investigations, Chapter 6 21 Fingerprint Forensic FAQs o Can fingerprints be erased? Only temporarily; they will grow back if removed with chemicals ( John Dillinger tried by putting acid on his fingertips.) o Is fingerprint identification reliable? Yes, but analysts can make mistakes (see page 140) o Can computers perform matches in seconds? No, but the FBI’s Integrated Automated Fingerprint Identification System (IAFIS or AFIS) can provide a match within 2 hours

Forensic Science: Fundamentals & Investigations, Chapter 6 22 The Future of Fingerprinting o New scanning technologies Yield clear detail in minute patterns Reduce analytical mistakes Analyze trace elements of objects on the skin o Technologies being developed use other physical features to identify people: Retinal patterns in in the eyes Facial patterns Pattern of veins in your palm of the hand

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

Forensic Science: Fundamentals & Investigations, Chapter Summary o Investigators search for patent, plastic, and latent prints. o Dusting with powders or using special chemicals can make latent fingerprints visible. o New developments may eliminate errors by analysts.