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Fingerprinting Forensic Science
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Fingerprinting
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Is it a match? You will be given 2 prints. Compare the second print to this print. Can you determine if it is a match?
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Major patterns What are the distinguishing patterns of these fingerprints? How would you describe them?
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6 Fundamental Principles of Fingerprints An individual characteristic. Unchanged during an individual’s lifetime. Characteristic ridge patterns
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Why do we have fingerprints? Provides better grip – Called dermal or friction ridges ? Makes perspiration easier on a hairless surface ? Improves sense of touch
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Skin Epidermis (outer skin) has 3 layers – Peridermal – Intermediate – Basal Dermis (under layer) – Amorphous fiber Basal Layer – new skin cells form
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Prints form in the fetus Forms between the 10 th – 17 th week Determined for life Basal layer – – Forms new skin cells – Grows faster than the upper layers and the dermis – Folds into interconnected ridges
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Prints Natural secretions - water, oils, salt Dirt Provide an impression on contacted surfaces Also on toes, soles of the feet, palms Kendall/Hunt Publishing Company 10
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Fingerprint formation
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Important Terms Dactyloscopy Patent fingerprint Plastic fingerprint Latent fingerprint Epidermal Basal layer Dermis Arch Loop Whorl Delta Core Minutia patterns
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Resources http://finger- prints.com/index.html http://finger- prints.com/index.html http://en.wikipedia.org/ wiki/Fingerprint http://en.wikipedia.org/ wiki/Fingerprint http://www.crimemuse um.org/library/forensic s/fingerprints.html http://www.crimemuse um.org/library/forensic s/fingerprints.html http://www.livestrong.c om/article/287440-the- development-of- fingerprints-in-babies/ http://www.livestrong.c om/article/287440-the- development-of- fingerprints-in-babies/
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Major visual patterns Loops 65% population Whorls 30% population Arches 5% population
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Classification of Fingerprints Three basic patterns: – Loop 65% – Whorls 10-20% – Arches 5% – Racial variations African (more arches), European (more loops), Asians/Orientals (more whorls)
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Loop A loop must have one or more ridges entering and exiting from the same side. Loops must have one delta. Types Radial—opens toward the thumb Ulnar—opens toward the “pinky” (little finger) Which type of loop is this, if it is on the right hand? Left hand? Delta
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Whorl Whorls have at least two deltas and a core. Four Groups Plain Central Pocket Double Loop Accidental Plain Whorl
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Whorl Central Pocket
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Whorl Double loop
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Whorl Accidental
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Arch Friction ridges that enter on one side of the finger and cross to the other side while rising upward in the middle. They do NOT have type lines, deltas, or cores. Types Plain Tented
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Identify each fingerprint pattern. Right Hand Left Hand Right Hand
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It’s time to make some prints! Avoid Partial Prints GOOD PRINT Get as much of the top part of your finger as possible!
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Henry-FBI Classification Developed by Edward Henry Allowed all sets of ten fingerprints in the world to be divided into 1024 groups Secondary and more complex classifications were created to allow for more groups
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Primary Classification The Henry—FBI Classification Based on WHORLS Each finger is given a point value rightleft
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Primary Classification Assign the number of points for each finger that has a whorl and substitute into the equation: right right left left left index ring thumb middle little + 1 right right right left left thumb middle little index ring +1 That number is your primary classification number =
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Individualization Henry-FBI Classification – Narrows into a group Ridge Classification – Uses minutiae to individualize fingerprints – In U.S. there are no legal requirements for # of points – Criminal courts accept 8 to 12 points – 150-200 minutiae in a good rolled print
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Kendall/Hunt Publishing Company 28 Fingerprint Minutiae
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Ridge Characteristics Minutiae—characteristics of ridge patterns Ridge ending Short ridge Dot or fragment Bifurcation Double bifurcation Trifurcation Bridge Island Enclosure Spur
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Comparison Can you identify the points?
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Fingerprint Minutiae
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How are fingerprints analyzed? The Automated Fingerprint Identification System—a computer system for storing and retrieving fingerprints Established in the 1970s IAFIS—the FBI’s Integrated Automated Fingerprint Identification System, which is a national database of all 10-print cards from all over the country Kendall/Hunt Publishing Company33
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Latent Prints Latent fingerprints Hidden Natural secretions of human skin Require development for them to become visible Most secretions come from glands: Eccrine—largely water with both inorganic (ammonia, chlorides, metal ions, phosphates) and organic compounds (amino acids, lactic acids, urea, sugars). Most important for fingerprints. Apocrine—secrete pheromones and other organic materials. Sebaceous—secrete fatty or greasy substances.
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Developing Latent Prints Requires substances that interact with secretions Attempt more than one technique, done in a particular order so as not to destroy the print
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Iodine Fingerprint
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Ninhydrin Fingerprint
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Cyanoacrylate Fingerprints
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40 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
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Other Prints Lips—display several common patterns Short vertical lines Short horizontal lines Crosshatching Branching grooves
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Kendall/Hunt Publishing Company 42 Other Prints Palm—friction ridges can be identified and may be used against suspects
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Kendall/Hunt Publishing Company43 Other Prints Footprints are taken at birth as a means of identification of infants.
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Kendall/Hunt Publishing Company44 Other Prints 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. Earprint catches murderer
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Kendall/Hunt Publishing Company45 Other Prints, continued Teeth —bite marks are unique and can be used to identify suspects. These imprints were placed in gum and could be matched to crime scene evidence.
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Other Prints The blood vessel patterns in the eye may be unique to individuals. They are used today for various security purposes.
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Which fingerprints are matches? Match the ones that are made by the same finger. In some cases, one print may appear two or three times.
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Matching can be facilitated by digital enlarging and comparing cropped areas, or by enlarging with a photocopier and using a transparency overlay. A = G = S This one is interesting; there are three separate impressions of the same finger with some very unique features. B = no match C = no match D = no match E = T F = J H = R I = no match K = O L = no match M = P N = Q
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Case Study: Madrid Bombings. Comparison of fingerprints Mayfield printsPrime suspect
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