ACOS 2.2, 2.3 Fingerprints Forensic Science

ACOS 2.2, 2.3 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 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 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 Francis Galton 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 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 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 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 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 Anatomy of a FP

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

ACOS 2.2, 2.3 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 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.