Chapter 4: Fingerprints

2 History First fingerprints were discovered in clay pottery during the T’ang Dynasty Dactyloscopy: study of fingerprints

3 History Alphonse Bertillion – First systematic attempt at personal identification Bertillion system – Relied on a detailed description of the subject – Combined with full length and profile photographs – System of precise body measurements called anthropometry

4 History Francis Galton – 1892 – Classic textbook finger prints At Galton’s insistence – British government adopted fingerprinting – Supplement to the bertillion system. Next step – Creation of classification systems – Capable of filing many thousands of prints – Logical and searchable sequence.

WHY FINGERPRINTS? The most positive means for identifying people. Because no two fingers with identical ridge characteristics The most positive means for identifying people. Because no two fingers with identical ridge characteristics Fingerprints form on a person before birth and remain unchanged until the body decomposes after death. Every fingerprint is unique!

WHAT IS A FINGERPRINT? A fingerprint is a pattern comprised of ridges and valleys. A Ridge – is a high. A Valley – is a depression or low. A fingerprint is a pattern comprised of ridges and valleys. A Ridge – is a high. A Valley – is a depression or low. Friction ridges are also found on our palms, feet and toes.

Ridge Valley

8 Fingerprint Principles Individual characteristic – Because no two fingers with identical ridge characteristics Remains unchanged during an individual’s lifetime General ridge patterns that permit systematic classification

9 Anatomy of Fingerprints Epidermis – Outer layer of the skin Dermis – Inner layer of the skin Dermal papillae – Layer of cells between the epidermis and dermis – Responsible for determining the form and pattern of the ridges on the surface of the skin

10 Anatomy of fingerprints Dermal papillae develop in the human 3 months Enlarge during growth

11 Anatomy of fingerprints Finger touches a surface – Perspiration – Oils from hairy portions of the body – Transferred onto surface Leaves fingerprint

12 Fingerprint patterns All fingerprints – divided into three classes – Loops – Arches – whorls L.A.W.

13 Loops A loop must have one or more ridges entering from one side of the print, re- curving, and exiting from the same side. – 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.

14 Figure4.3 Loop pattern. Loops

15 Loops Must have one delta

16 Whorls

17 Whorls Divided into four groups – Plain – Central pocket loop – Double loop – Accidental All have a minimum of two deltas

18 Whorls Plain whorl and central pocket loop have at least one ridge that makes a complete circuit Double loop: two loops combined into one fingerprint Accidental – Two or more patterns – Or pattern not covered by the other categories

19 Arches

20 Arches Least common of general patterns – Plain arches – Tented arches – Arches do not have deltas, or cores

21 Plain Arches Ridges entering from one side of the print Rising and falling Exiting on the opposite side Like a wave

22 Tented Arches Sharp up-thrust or spike The ridges meet at an angle that is less than 90 degrees

Questions???

How are fingerprints compared? A.Fingerprints are compared by noting the ridge characteristics on two prints to determine whether or not they match. B.An identification is established when a number of these characteristics occupy the same relative position on the two prints. A.Fingerprints are compared by noting the ridge characteristics on two prints to determine whether or not they match. B.An identification is established when a number of these characteristics occupy the same relative position on the two prints.

Fingerprints and a fingerprint classification schema involving six categories: (a) arch, (b) tented arch, (c) right loop, (d) left loop, (e) whorl, and (f) double loop. Critical points in a fingerprint, called core and delta, are marked as squares and triangles.

FINGERPRINT IDENTIFICATION

RIDGE CHARACTERISTICS (Minutiae) COMMON OCCASIONAL RARE Ending Ridge

Ridge Characteristics Use these characteristics as points of identification when comparing fingerprint samples. The more points you can find in common, the better the match!

RIDGE CHARACTERISTICS MAGNIFIED Points 1, 2, 4, 5 are Ending Ridges Points 8, 10, 11 are Bifurcations Point 7 Short Ridge Points 3 and 9 are Dots Point 6 is an Enclosure (ISLAND) Point 6 is an Enclosure (ISLAND)

Review of fingerprint types

Arches Arches 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 Arch Ridges enter on one side and exit on the other side. Tented Arches Similar to the plain arch, but has a spike in the center. Spike or “tent”

Loops Loops 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. De lta Ulnar Loop (Right Thumb) Loop opens toward right or the ulna bone. Radial Loop (Right Thumb) Loop opens toward the left or the radial bone. NOTE: On the left hand, a loop that opens to the left would be an ulnar loop, while one that opens to the right would be a radial loop.

Whorls Whorls 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 Whorl Central 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

Identify each fingerprint pattern. Right Hand Left Hand Right Hand

Presenting Fingerprints as Evidence No legal requirements on the number of points but generally the courts will accept 8 to 12 points of similarity as sufficient proof. Fingerprints do not lie but human error might account to wrongful convictions.

39 Types of Prints Visible & Latent Prints

40 Latent Prints Invisible fingerprints Finger touches a surface Body perspiration and/or oils present Transferred to that surface Leaves impression

41 Visible Prints Fingers touch a surface after contact with a colored material such as blood, paint, grease, or ink Plastic prints: left on a soft material, such as putty, wax, soap, or dust Little problem to the investigator

42 Visualizing Latent Prints

43 Detecting Prints Hard nonabsorbent surfaces – Glass, mirror, tile, painted wood – Developed by the application of a powder – Can be lifted by clear tape & examined Porous surfaces – Papers, cardboard, and cloth, styrofoam, leather – Require treatment with a chemical

Ninhydrin Reacts with amino acids left by finger Produces a orange /purple color (Ruhemann’s purple) Commonly used with paper and porous surfaces 44

45 Iodine Fuming Heat iodine crystals (produces iodine vapors) Combine with latent prints (react w/ oils on finger) to make them visible – Iodine prints are not permanent – Will fade – Must photograph the prints immediately – Works best on porous paper.

Silver nitrate Reacts with the salt left from sweat in a dried print. AgNO 3 + NaCl AgCl *converts to dark Ag 2 O Turns prints brownish-purple

47 Super Glue ® Most widely used method to develop latent prints Best used on nonporous surfaces such as metals, glass, adhesive tapes and plastic. Leaves a white, permanent impression can be treated with powders or fluorescent dyes to create a sharper contrast. 98 to 99 percent cyanoacrylate ester Super Glue fuming – Fuming chamber (for up to six hours)

48 Reflected UV Imaging System RUlVIS No chemicals or powder Locate With light source investigator develops the print in the most appropriate fashion

49 Powders Powders, available in a variety of colors, can be applied with a brush or magnetic wand, and adhere to perspiration and/or body oils of the print.

Other methods Photograph

Digital Imaging- AFIS Digital image: of fingers are pressed against a glass plate and scanned to a screen. ** can be enhanced, compared and sent to AFIS within minutes. AFIS can compare hundreds of thousands of prints in less than a second. 51

Digital Imagining: IAFIS Replaced tradition method of fingerprinting. Contains more than 55 million computerized fingerprint records of known criminals. Live Scan electronic fingerprints devices transmit the time of arrest or booking to a central IAFIS database to provide immediate positive identification, check for with any suspect latent prints on file, and provide criminal history.