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Fingerprints

Fingerprints. Forensic Science. Early Techniques. Alphonse Bertillon - system of precise body measurements (anthropometry) Bertillon’s system rested on idea that body measurements never change after the age of 20

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Fingerprints

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  1. Fingerprints Forensic Science ACOS 2.2, 2.3

  2. Early Techniques • Alphonse Bertillon - system of precise body measurements (anthropometry) • Bertillon’s system rested on idea that body measurements never change after the age of 20 • Skeleton sizes were thought to be so diverse that no two people could have the same measurements. • System included 11 measurements: outstretched arms, head length and width, left foot length, left little finger length, trunk height, body height, width and length of right ear, length of the left forearm, sitting height. • He also documented hair color, eye color, and skin tone. ACOS 2.2, 2.3

  3. Anthropometry • For twenty years, anthropometry was thought to be the most accurate measurement system. • Once police looked for a more efficient way to identify people, the fingerprinting system came through. • Today, fingerprinting is the pillar of criminal identification. ACOS 2.2, 2.3

  4. Fingerprint Timeline • Documentation of Chinese using FP’s to sign legal documents as far back as 3,000 years ago • Several years before Bertillon began work, FP’s were used in India to “bind” someone to a contract. • Scottish physician, Henry Fauld, published papers on the potential application of FP’s to personal identification. ACOS 2.2, 2.3

  5. Francis Galton • 1892- published book Finger Prints • He discussed the anatomy of fingerprints and suggested techniques for recording them • Galton also assigned fingerprint types: loops, whorls, and arches • His book demonstrated that no two prints are exactly alike • Prints remain unchanged year after year ACOS 2.2, 2.3

  6. United States v. Byron C. Mitchell • Pennsylvania-1999 • Admissibility of fingerprint evidence was challenged • The defense stated that the fingerprints could not be proven to be unique under the current research. • After 4 days of hearings, the judge upheld the research on fingerprints and ruled that: • Human friction ridges are unique and permanent • Human friction ridge skin arrangements are unique and permanent ACOS 2.2, 2.3

  7. No 2 Identical Prints • Galton calculated that there are 64 billion possible fingerprint combinations. • Galton’s calculations were challenged and no matter what formula is used there is the same result: • The probability for the existence of two identical fingerprint patterns in the world’s population is extremely small. • In 90 years of research, no two prints have ever been identical. ACOS 2.2, 2.3

  8. Minutiae Points • AKA: Ridge Characteristics • Def.: The identity, number, and relative location of characteristics that impart individuality of a fingerprint • An easier definition: the ridges and valleys of a fingerprint • There are as many as 150 minutiae points and ridges on the average print ACOS 2.2, 2.3

  9. Some Reality of prints • CSI Lies to You!!! • Former CSI from the Gadsden Police Department, Deanna Rice: • “I have never lifted a complete print at a crime scene. Tell me what criminal is stupid enough to gingerly press their fingers on a smooth surface just so I can get their fingerprints” ACOS 2.2, 2.3

  10. Anatomy of a FP ACOS 2.2, 2.3

  11. Unchanging Prints • Similar friction ridges and minutiae can be found on the palms of the hand and on the feet. • These skin characteristics were designed by nature to enhance our grip and resist slippage. • These ridges and minutiae do not change throughout life. ACOS 2.2, 2.3

  12. Frankensteining • Can you change your fingerprints? • The answer is NO!! • Your fingerprints are created during womb development • You can not ever change your fingerprints • You can damage or mutilate them, but that just makes you more unique ACOS 2.2, 2.3

  13. Skin Layers • Outer layer of skin: Epidermis • Inner layer of skin: Dermis • Layer separating the 2 layers: papillae ACOS 2.2, 2.3

  14. Dermal Papillae • Your fingerprints are determined by the papillae layer • In order to alter your prints you must damage through the first layer of skin…ouch!!! • Why not just wear gloves? ACOS 2.2, 2.3

  15. Latent Prints • Your skin has openings called pores that are the location of perspiration of sweat and body oils. • When you make contact with a surface your body oils stick to a surface in the shape of your fingerprints. • Prints left with this technique at a crime scene are called latent prints. ACOS 2.2, 2.3

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