5.2 Fingerprints-2

5.2 Fingerprints-2 - Forensic Biology Dactyloscopy •...

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Unformatted text preview: Forensic Biology Dactyloscopy • Lecture 1: Forensic Serology • Lecture 2: Fingerprints • Lecture 3: DNA analysis Greek daktylos, the width of one finger skopein, to examine The use of Fingerprints for Identification Dr. B. L. Lim Associate Professor School of Biological Sciences [email protected] Tel: 22990826 Fingerprint Identification Why are fingerprints important in forensic? • 100 % unique to the individual • Do not change with AGE! • Friction ridge patterns vary within limits which allow for classification • Identical Twins? 1 out of 1060!! Fingerprint formation 1987 2000 The ridges of a fingerprint are formed by the dermal papillae during fetal development and remain permanent throughout one’s lifetime. •Wound or burn? 1 Secretion from the sweat gland What is the function of the ridges on our fingers which create fingerprints? INORGANIC Chlorides Metal ions Sulfates Phosphates Ammonia water (>98%) ORGANIC Amino acids Urea Uric acid Lactic acid Sugars Creatinine Choline Fingerprint Sensors Detection of Fingerprints in crime scene - Fingerprints on non-porous surfaces tend to be more fragile since the oils can easily be wiped away or smudged. (Glass, Metals, Plastics) -Porous surfaces tend to be better for lifting fingerprints since the oils form the skin are absorbed. (Paper, Wood, textiles) Optical Silicon-based capacitive sensor Ultrasound Thermal Examination sequence in crime scene Visual Examination Forensic Light *** Develop the prints *** Documentation/Photograph Forensic Light http://www.cbdiai.org/Reagents/main.html Invisible (Latent) Fingerprints 1. Super glue fuming - the glue is heated and the fumes condense onto the surface so that a print is formed. 2. Ninhydrin spray – porous surfaces 3. Powders - non-porous surfaces Visible and fluorescence powders. 4. Forenic (UV) light can reveal latent fingerprints treated with fluorescence powders. http://www.sirchie.com/overviewToolsMethods.aspx 2 Super glue fuming 1. Heating of cyanoacrylate to create fume 2. First discovered by Japanase officers (1977) (http://onin.com/fp/cyanoho.html#Background_Info) 3. Ninhydrin spray •Fingerprints on porous surfaces and wax •React with amines (on proteins secreted from sweat glands) Procedures http://www.evidentcrimescene.com/cata/glue/glue.html Application of powders Powder: Stick on fingerprints Brush: Remove background Overall: Signal to noise Forensic (UV) light Fluorescence powders www.sirchie.com/Manuals/pdf/FACII_TI02-113ENG-REV1E.pdf Victim Identification: Fingerprinting a corpse Schematic depicting latent-print detection with the aid of a laser. A fingerprint examiner, wearing safety goggles containing optical filters, examines the specimen being exposed to the laser light. The filter absorbs the laser light and permits the wavelengths at which latent-print residues fluoresce to pass through to the eyes of the wearer. Courtesy Federal Bureau of Investigation, Washington, D.C. Post-Mortem Fingerprinting 3 Sir Francis Galton F.R.S. 1822-1911 the inventor of fingerprint identification Fingerprints can be classified based on the ridge flow pattern. •Pattern types •Sizes of these patterns •Positions of these patterns Fingerprints can be grouped into arches, loops, whorls, and composites of these types. Arch patterns Loop pattern Whorl patterns 4 Fingerprints can be distinguished based on the ridge characteristics. Fingerprint Patterns Fingerprint Evaluation Automated Fingerprint Identification System (AFIS) A forensic optical comparator for matching fingerprints. 5 Fingerprint Image Enhancement Feature Extraction High contrast print Typical dry print Energy map Low contrast print Typical Wet Print Frequency map Feature Matching A fingerprint exhibit illustrating the matching ridge characteristics between the crime-scene print and an inked impression of one of the suspect’s fingers. Courtesy New Jersey State Police. Third Level Detail Advantages • studying the pores and the outlines of the fingerprint ridges. • developed on clear plastic with cyanoacrylate fuming Vs Disadvantages 6 Do twins have identical fingerprints? What leads to identical twins having non-identical fingerprints? The Future of Forensic Sciences Multibiometrics Systems spoofed or cadaverous fingers Artificially created Biometrics Attacking Via Input Port Attack at the Database 7 ...
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This note was uploaded on 09/06/2010 for the course YSCN YSCN0017 taught by Professor Prof during the Spring '08 term at HKU.

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