AN INFALLIBLE MEANS OF HUMAN ID Fingerprints

History of Fingerprinting-1 Early use of fingerprints Used by Chinese to sign legal documents 1880 Henry Fauld suggested skin ridge patterns could be important. Bertillon measurement system was used in favor of fingerprints in the 1880’s

History of Fingerprinting-2 Early classification of fingerprints 1892 Francis Galton published Finger Prints, the first book of its kind  Discussed anatomy of fingers  Discussed methods of recording them  Demonstrated that no two prints are identical  Proposed 3 pattern types: loops, arches, and whirls Several systems for classification were developed  US uses Sir E.R. Henry’s system to file fingerprints

History of Fingerprinting-3 Adoption of fingerprints Bertillion measurement system was highly susceptible to error. NY City Civil Service Commision adopts first systematic use of fingerprints in finger prints from Bureau of Investigation and Leavenworth were merged. FBI has the worlds largest collection of fingerprints

Fundamental Use of Fingerprints-1 First Principle: A finger print is an individual characteristic; no two fingers have yet been found to possess identical ridge characteristics.  Galton's calculation: predicts the possibility of 64 billion different fingerprints.  Verified by millions of individuals who have had their prints taken and classified.  FBI has nearly 50 million prints on file, no two the same.  Individuality of a fingerprint is determined by the ridge characteristics.

Fundamental Use of Fingerprints-2 Second Principle: A fingerprint remains unchanged during and individuals lifetime.  Fingerprints are a reproduction of the friction skin ridges on the palm side of the fingers and thumbs.  Designed for a firmer grip and resistance to slipping.  Friction skin ridges consist of hills and valleys and corresponds to the black lines of a fingerprint impression

Fundamental Use of Fingerprints-3 Second Principle: Cont. Skin:  Composed of layers of cells.  Outer layer= epidermis  Boundary between epidermis and dermis= dermal papillae  Inner layer= dermis  The dermal papillae determines the pattern and form of the ridges in the fetus.  Each ridge has a line of pores that release perspiration and oil  Prints deposited on a surface are known as latent fingerprints

Fundamental Use of Fingerprints-4 Third Principle: Fingerprints have general ridge patterns that permit them to be systematically classified.  Fingerprints are divided into 3 classes:  Loops (65% of population have)  Whorls (35% of population have)  Arches (5% of population have)

Classification of Fingerprints Primary classification is the first step in classifying fingerprints under the FBI system. The presence or absence of the whorl pattern is the basis for determination of the primary classification. R. Index + R. Ring + L. Thumb + L. Middle + L. Little R. Thumb R. Middle R. Little L. Index L. Ring  Finger of the first pair=16  Finger of the second pair=8  Finger of the third pair=4  Finger of the fourth pair=2  Finger of the fifth pair=1  Any finger with loops or arches=0

Automated Fingerprint I.D. Systems AFIS is the FBI’s fingerprint database.  Converts the image of a fingeprint into a digital minutiae that contain data showing ridges at their points of termination (ridge endings) and their branching into two ridges.  Livescan is an inkless device that captures digital images of fingerprints and transmits them to AFIS

Methods of Detecting Fingerprints-1 Locating Fingerprints Reflected Ultraviolet Imaging System (RUVIS)  Locates prints on nonabsorbant surfaces w/o aid and detects the print in its natural state (Fig 14-11) Hard nonabsorbant surfaces (glass, mirrors, tile, and painted wood)  Developed by application of powder or treatment with super glue Soft pourous surfaces (papers, cardboard, and cloth)  Require treatment with one or more chemicals

Methods of Detecting Fingerprints-2 Developing Fingerprints Fingerprint Powders  Commercially available in variety of colors.  Applied with camel hair or fiberglass brush  Color that provides most contrast to surface print it removed from is used.  Fluorescent powders fluoresce under UV light and photograph can be taken.  Magna Brush can be used to spread a powder. Does not have any bristles therefore the print is not destroyed or damaged.  Useful on leather and rough surfaces

Methods of Detecting Fingerprints-3 Developing Fingerprints cont. Iodine Fuming  A technique for visualizing latent fingerprints by exposing them to iodine vapors.  Suspect sample is placed in a cabinet with iodine crystals and as the crystals heat up prints become visible.  Iodine prints are not permanent and fade and prints must be photographed immediately.  Prints can be fixed with 1% solution of starch in water and prints will last up to several months.

Methods of Detecting Fingerprints-4 Developing Fingerprints cont. Ninhydrin  A chemical reagent used to develop latent fingerprints on porous materials by reacting with amino acids in perspiration  Forms a purple-blue color in presence of amino acids.  Sprayed using aerosol can.  Prints appear w/in an hour or two after application  Weak prints can take up to hrs.  Can be sped up if sample is heated.

Methods of Detecting Fingerprints-5 Developing Fingerprints cont. Physical Developer  A silver nitrate-based reagent formulated to develop latent fingerprints on porous surfaces.  Very effective  Used if ninhydrin fails.  Will wash away traces of proteins so other developing processes must be used first.

Methods of Detecting Fingerprints-6 Developing Fingerprints cont. Super Glue Fuming  A technique for visualizing latent fingerprints on nonporous surfaces by exposing them to cyanoacrylate vapors: named for commercial product Super Glue.  Used on metal, electrical tape, leather and plastic bag surfaces.  Development occurs when fumes from the glue adhere to the latent print (appears white).  Use of a small handheld wand makes this technique easy to do at a crime scene or lab.

Methods of Detecting Fingerprints-7 Developing Fingerprints cont. Other Techniques  Use of lasers to induces flourescence.  Use of alternate light sources: High Intensity quartz halogen, Xenon-arc lights  Use of DFO (1,8 diazafluoren-9-one) substitute for ninhydrin.

Preservation of Developed Prints Special camera for fingerprint photography is used:  Small objects w/ prints  Are preserved in its entirety  Covered w/ cellophane  Large objects w/ prints  Use of powders can allow lifting of the prints with adhesive tape.

Digital Imaging for Fingerprint Enhancement Once the print is visualized it is permanently preserved for future comparison and for possible used. A photograph is taken before any further attempts at preservation is made.