FINGERPRINTS Chapter 14 Forensic Science History of

FINGERPRINTS Chapter 14 Forensic Science

History of Fingerprinting ü Bertillon (1883) First system for identification ü Galton (1892) Published first textbook: Finger Prints ü Henry (1897) Fingerprint system adopted by Scotland Yard ü NY City Civil Service Commission (1901) used to certify all applications ü FBI (1924) combined prison records from Leavenworth with their records to form the first national fingerprint “database”.

Three Fundamental Principles ü Fingerprints show individual characteristics ü Fingerprints do not change over a lifetime ü Fingerprints have ridge patterns that can be easily classified

1 st Principle: No two fingerprints look alike ü Classified by ridge patterns or minutiae ü Ridge patterns must match in both characteristics and location on the finger ü No national standard but 8 -16 ridge patterns are needed between a unknown and known fingerprint for there to be a match

2 nd Principle: Fingerprints stay the same over a lifetime ü Friction ridges found on lips, fingers and palms of hands and soles of feet ü Outer layer of skin - epidermis ü Inner layer - dermis ü Junction between the two layers is - dermal papillae ü John Dillinger tried to obliterate his finger prints by making deep cuts and pouring sulfuric acid into the cuts. Within a few years the same friction ridge patterns returned with some scaring. Post Mortem fingerprints taken by the FBI confirmed that his prints were unchanged.

2 nd Principle ü Raised lines or hills Ridges ü The valleys between the hills - Grooves ü Pores in between the ridges are openings for sweat glands ü Sweat and oils leave an impression on the surface - latent print

3 rd Principle: Classified Ridge Patterns ü Three Ridge Classes: LOOPS - 60 to 65% WHORLS - 30 to 35% ARCHES - 5% Percentage of the patterns found on the epidermis in the general population

Classification

LOOPS ü In order to distinguish between ulnar and radial loops you must: ü 1) know from which hand the loop pattern comes from 2) place your hand palm side down over top of the impression and determine if the recurving ridges originate from the little finger side or the thumb side. ü 3) If the ridges flow in from the little finger side this would be an 'ulnar' loop. ü 4) If the ridges flow in from the thumb side this would be a 'radial' loop.

WHORLS ü All whorls have at least two deltas. ü A plain whorl has at least one ridge that makes a complete circle ü The ridge can be in the shape of a spiral or an oval.

ARCHES ü The Arch pattern is made up of ridges lying one above the other in a general arching formation. ü The tented arch pattern consists of at least one upthrusting ridge, which tends to bisect superior ridges at right angles, more or less.

Basics ü All fingerprints are divided into one of the three general patterns: loops whorls or arches. ü The individuality of a fingerprint is determined by a careful study of ridge characteristics ü Latent (invisible) fingerprints are produced when you touch a smooth surface and transfer an impression of your finger with sweat and oils

The Henry System ü In 1901 – the original classification system used for fingerprints was developed by a man named Henry. ü He converted all 10 fingers into a series of letters and numbers. ü Both hands could be expressed as a fraction. ü Problem was the system was designed for only about 100, 000 sets of prints. ü The number of people exceeded the system very quickly.

FBI System ü By adding extensions and expanding the original Henry System, the FBI was able to create a limitless system for comparing fingerprints. ü This system provides the examiner with a more limited pool of candidates from which to examine for matches.

Henry System Basics ü System is based on the presence of whorls ü Any finger that has an arch or loop is assigned a 0. ü Whorls on first pair is 16 on second – 8, third pair -4, fourth – 2 and last pair value of 1 ü After all the fractions are added a value of 1/1 is added to the total for the final fraction R Index R Ring L Thumb L Middle L Little 1 R thumb R Middle R Little L Index L Ring 1 16 0 0 1 = 17 0 8 0 0 0 1 8

Integrated Automated Fingerprint Identifcation System (IAFIS) ü Ability of the computer to scan and digitally encode fingerprints ü The encoding allows minutiae to be rapidly scanned ü Can screen a set of 10 prints against a file of 500, 000 sets of 10 prints in. 08 seconds ü Ridge endings (terminations) ü Branching of ridges (bifurcations) ü Screen out imperfections in latent prints ü Can send prints immediately to FBI database

DETECTING FINGERPRINTS Locating fingerprints ü Three kinds of crime scene prints: ü Visible – can be seen without technology ü Latent – not visible without some technology ü Plastic – impressions made in soft materials such as soap, wax or putty ü Visible and plastic are easy to find but latent is more difficult ü Different surfaces require different visualizing methods ü Hard non-porous surfaces (glass, tile, painted wood) require visualizing powders or Super glue

DETECTING FINGERPRINTS ü Soft and porous surfaces (cloth, paper, cardboard) require chemical treatment ü Can use RUVIS (Reflected Ultraviolet Imaging System) which locates prints on soft surfaces without the use of chemicals with UV light

DEVELOPING LATENT PRINTS ü POWDERS: ü FUMING: ü Adhere to perspiration and body oils ü Iodine – iodine sublimates when heated giving off fumes. ü Almost any color – grey and black being most common ü Grey – aluminum dust ü Black –carbon or charcol ü Magnetic – charged ü Fluorescent – glow under UV light ü The fumes adhere to the latent print ü Old technology – does not last long print visible fades in minutes

DEVELOPING PRINTS ü NINHYDRIN ü FUMING: ü Super glue (Crazy glue) can visualize a print on non-porous surfaces as well as metals, tape, leather and plastic bags ü Heating the Super glue releases cyanoacrylate ester fumes ü Fumes produce a white fluffy print ü The chemical reacts with amino acids to produce a purple-blue color ü Usually used as an 0. 6 % solution sprayed as an aerosol on porous surfaces ü Takes 1 to 48 hours can increase developing by heating in an oven ü Effective on paper that was 15 years old

DEVELOPING PRINTS ü PHYSICAL DEVELOPER ü Chemical mixture – silver nitrate based ü Works even if item was wet –then dried. ü Used as the “last resort” because washes away all traces of proteins ü NEWEST TECHNOLOGY Laser light can detect latent prints that fluoresce with certain components of sweat. Alternate light sources: High-intensity quartz halogen Xenon-arc LED’s (light emitting diodes) DFO (1, 8 -diazafluoren 9 -one) Chemical works with alternate light sources

PRESERVING DEVELOPED PRINTS ü If the object the print is ü Once a print is developed it must be preserved as evidence on is small – the entire object should be taken to the laboratory ü STEP ONE: photograph developed print ü If the object is too large then the developed print must be “lifted”. ü STEP TWO is determined by the size of the object the print is on ü Can use special clear tape to lift a print developed with a powder ü Tape with print is placed on a card with good background contrast

DIGITAL IMAGINGü Digital imaging converts ü Lifted fingerprints are not usually in perfect condition – making analysis even more difficult ü Digital imaging programs can now enhance the lifted/partial prints to make identification more accurate a fingerprint image into pixels ü Can be done with a scanner or digital camera