Fingerprints Fingerprints Fundamental Principles of Fingerprints A

Fingerprints

Fingerprints Fundamental Principles of Fingerprints A fingerprint is an individual characteristic. A fingerprint remains unchanged during an individual’s lifetime. Fingerprints have general characteristic ridge patterns that permit them to be systematically classified. Even twins have different fingerprints Chapter 4 Kendall/Hunt Publishing Company 2 2

Fingerprints Skin L Fingerprints arise from the dermal papillae (layer of cells between epidermis and dermis) L Every person has different fingerprints (even twins) L Perspiration (from sweat glands), skin cells, proteins, fats/oils, and other materials are deposited when fingers touch a surface Chapter 4 3

Fingerprints Dactyloscopy: study of comparing fingerprint ridge structures. L Latent fingerprints: invisible fingerprints L Are made patent by adding powder, superglue fuming, or chemical reactions L Patent (Visible) Prints: fingerprints (from blood, ink, paint, oil, etc. ) L Plastic (Impressed) Prints: fingerprints in a soft material such as putty, butter, clay, wax Chapter 4 4

Fingerprints LOOP Chapter 4 WHORL Kendall/Hunt Publishing Company ARCH 5 5

Fingerprints 1. Loops: flow from one side of the finger, rise and then flow back to the same side of the finger LUlnar Loop: (ridge starts on little finger side, extends across finger and curves back towards little finger side) LRadial Loop: (ridge starts on thumb side, extends across the finger and curves back to thumb side) LDouble Loop: has two loops Chapter 4 Left Hand Double Loop 6

Fingerprints 2. Arches: ridges flowing from left to right with a rise or hill in the center. LTented Arch: looks like it has a tent pole in the middle 3. Whorls: circular ridges Chapter 4 7

Fingerprints Other Types of Fingerprints LCentral Pocket Loop LLateral Pocket Loop LComposite LAccidental Chapter 4 8

Fingerprints What type of fingerprint are each of the following? Chapter 4 Kendall/Hunt Publishing Company 9 9

Fingerprints Fingerprint Minutiae L Bifurcations: ridges that split into two ridges L Ridge ending: ridge that ends L Dot: tiny round ridges L Island: short ridge L Enclosure (eye): ridge that forks, and then comes back together L Trifurcation: ridge that splits into three ridges L Delta: triangle-like ridge L Bridge: ridge connecting two ridges L Spur: small ridge spurring off another ridge L Core: center of whorl Chapter 4 10

Fingerprints Fingerprint Minutiae Chapter 4 Kendall/Hunt Publishing Company 11 11

Fingerprints LIdentify as many minutiae as possible on the following fingerprint: Chapter 4 12

Fingerprints Primary Classification The Henry-FBI Classification System Each finger is given a point value. right Chapter 4 left Kendall/Hunt Publishing Company 13 13

Fingerprints Primary Classification, continued Assign the number of points for each finger that has a whorl and substitute into the equation: right index right ring left thumb left middle left little +1 = right thumb right middle right little left index left ring +1 That number is your primary classification number. Chapter 4 Kendall/Hunt Publishing Company 14 14

Fingerprints Comparison There are no legal requirements in the United States on the number of points required for a match. Generally, criminal courts will accept 8 to 12 points of similarity. Chapter 4 Kendall/Hunt Publishing Company 15 15

Fingerprints Developing Latent Prints Developing a print requires substances that interact with secretions, causing the print to stand out against its background. Powders—adhere to both water and fatty deposits. Choose a color to contrast with the background. Iodine—fumes react with oils and fats to produce a temporary yellow-brown color. Ninhydrin—reacts with amino acids to produce a purple color. Silver nitrate—reacts with chloride to form silver chloride, a material that turns gray when exposed to UV light. Cyanoacrylate—“superglue” fumes react with water and other fingerprint constituents to. Kendall/Hunt Publishing Company. form a hard, whitish deposit Chapter 4 16 16

Fingerprints Other Prints Lips—several common patterns 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 Palm—friction ridges can be identified and may be used against suspects Footprints are taken at birth as a means of identification of infants. Chapter 4 Kendall/Hunt Publishing Company 17 17

Fingerprints Other Prints, continued Earprint catches murderer A man has been convicted of suffocating an eldery woman on the basis of earprint evidence. The assailant was caught after police matched the inprint of his ear on the victim’s window. Police believe that the thief put his ear to the window to listen for signs of anyone home. Chapter 4 The blood vessel patterns in the eye may be unique to individuals. They are used today for various security purposes. Kendall/Hunt Publishing Company 18 18

Fingerprints AFIS The Automated Fingerprint Identification System—a computer system for storing and retrieving fingerprints Established in the 1970 s, AFIS enables law enforcement officials 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 database 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 Chapter 4 Kendall/Hunt Publishing Company 19 19

Fingerprints Visualization of Fingerprints: Powders L Powders make latent prints visible: used on hard/ non-absorbant surfaces such as glass, mirror, tile, painted wood) L Black powders are used on light-colored backgrounds and silver/white powders are used on dark-colored backgrounds. L Before applying powder to brush, gently spin the brush between index finger and thumb to separate bristles. L Place a small amount of powder on the brush and gently twirl to remove excess powder. L Twirl the brush while very lightly brushing the bristles across the surface of the fingerprint. If ridge detail appears, brush very lightly in the direction of the ridge flow. L If less contrast is seen, stop because the print is being brushed away. L Flourescence: Some powders fluoresce under UV light Chapter 4 20

Fingerprints Lifting Fingerprints 1. Hold a piece of clear tape (slightly larger than fingerprint) in both hands. 2. Attach the end of the tape in the right hand to the surface slightly to the right of the print. 3. Using the right thumb, smooth the rest of the tape onto the surface, working from right to left and then from center outwards. 4. Lift the tape and apply it to a piece of paper (from right to left) 5. Record date, time, name, location, and any other information about the print. Chapter 4 21

Fingerprints Fingerprint Scavenger Hunt 1. Find people with the 12 different fingerprint types: L Arch L Tented arch L Ulnar loop (right hand) L Radial loop (right hand) L Ulnar loop (left hand) L Radial loop (left hand) L Whorl L Central pocket loop L Double loop L Lateral pocket loop L Composite L Accidental Chapter 4 2. Collect fingerprints using ink pads and placing their fingerprint on an index card. 3. Record name of person, finger, right or left hand, and type of fingerprint. For example: Amy Urling Right Ring Finger Ulnar Loop 22