Fingerprinting

Physical Evidence

Wherever he steps, whatever he touches, whatever he leaves—even unconsciously—will serve as a silent witness against him. Not only his fingerprints and his shoeprints, but also his hair, the fibers from his clothes, the glass he breaks, the tool mark he leaves, the paint he scratches, the blood or semen he deposits or collects—all of these and more bear mute witness against him. This is evidence that does not forget. It is not confused by the excitement of the moment. It is factual evidence. Physical evidence cannot be wrong; it cannot perjure itself; it cannot be wholly absent. Only in its interpretation can there be error. Only human failure to find, study, and understand it can diminish its value.

Paul L. Kirk, Crime Investigation

FingerprintingFirst form of personal identification system

developed by French police expert Alphonse Bertillon in 1883

Bertillon System aka Anthropometry: Full length and profile photographs Precise body measurements Detailed description of the person of interest

(portrait parle)

Based on premise that dimension of the human bone system remained fixed from age 20 until death

Body Measurements11 routine measurements, including height, reach, width

of head, length of left foot, wrist circumference, etc.

Early 1900s: fingerprinting as standard police practice evolved

Scot Henry Fauld, in 1880, published a paper about using fingerprinting for personal identification

Francis Galton, 1892, Finger Prints Loops, arches, and whorls An individual’s prints remained unchanged over lifetime Insisted British government adopt his system to supplement

Bertillon system

Fingerprinting technologyMove away from Bertillon system to Fingerprinting

1903, William West and Bertillon doppelganger Will West at Fort Leavenworth prison

1901, NYC Civil Service Commission adopted fingerprinting

1904 St. Louis World’s Fair: American police officials trained in fingerprint identification technology by Scotland Yard Fingerprinting began to be used in earnest in most US cities

1924, Bureau of Investigation and Ft. Leavenworth fingerprint records combined to become FBI fingerprint database

Challenges to Fingerprinting1999: United v Byron C. Mitchell in PA

Defense disputed claim that fingerprints are unique and distinguishable.

Four day trial, judge upheld Daubert ruling that fingerprints are admissible as scientific evidence human friction ridges are unique and permanent human friction ridge skin arrangements are

unique and permanent

Fingerprint PrinciplesFingerprints are a reproduction of friction skin ridges found

on the palm side of the fingers and thumbs.

The basic principles underlying the use of fingerprints in criminal investigations are that:

1. A fingerprint is an individual characteristic because no two fingers have yet been found to possess identical ridge characteristics (minutiae);

There are as many as 150 minutiae on the average finger The identity, number, and relative location of these

minutiae impart individuality

Galton’s calculation

1 in 1 x 1060, i.e. 64 billion possible different fingerprint patterns

In the past 100 years, no two set of fingerprints have been found to be identical

Fingerprints are individualized by its ridge characteristics (aka minutiae) Ridge endings Bifurcations Enclosures Lakes Ridge dots

Fingerprint ridge characteristics.

8-16 matches must be made between fingerprints to be considered from the same individual

1995: Ne’urim Declaration: no set number of matching characteristics can be defined, must be based on experience and knowledge of the expert

A fingerprint exhibit illustrating the matching ridge characteristics between the crime-scene print and an inked impression of one of the suspect’s fingers.

2nd Principle: Unchanged2. A fingerprint will remain unchanged during an individual’s lifetime

Friction skin ridges (palm side of fingers and thumbs, and on palms and soles of feet) Ridges correspond to ridges and grooves (hills and valleys)

Epidermis (outer layer of skin)

Dermis (inner layer of skin)

Dermal Papillae (boundary between dermis and epidermis) determine form and pattern of ridges and grooves

Sweat pores: discharge perspiration, oil transmission,

Once the dermal papillae develop in the human fetus, the ridge patterns will remain unchanged throughout life except to enlarge during growth.

Final Dermal Surface

Epidermis

FurrowGroove

Papillae in double row arrangement

Principle TwoOnce the finger touches a surface, perspiration,

along with oils that may have been picked up by touching the hairy portions of the body, is transferred onto that surface, leaving the finger’s ridge pattern (a fingerprint). Pints deposited in this manner are invisible to the eye and are commonly referred to a latent fingerprints.

Cross-section of human skin.

Can Fingerprints be Destroyed or Removed?

• Typically, no. A minor injury (scrape, scratch or even burn) won't affect the structure of the ridges in your fingerprints -- new skin reforms in its original pattern as it grows over the wound.

• But each ridge is also connected to the inner skin by small projections called papillae. If these papillae are damaged, the ridges are wiped out and the fingerprint destroyed.

www.science.howstuffworks.com/fingerprinting

Can Fingerprints be Destroyed or Removed?

• Chicago bank robber John Dillinger reportedly burned his fingertips with acid in the 1930s.

• With new technology and fingerprint scanning security, law enforcement officials worry that would-be criminals might try to steal entire fingers for the prints.• Robbers in Malaysia cut off a man's fingers so

they could steal his Mercedes. • Companies that make biometrics security

equipment realize the potential dangers of this system, and are now creating scanners that detect blood flow to make sure the finger is still alive.

www.science.howstuffworks.com/fingerprinting

3rd Principle: General patterns

3. Fingerprints have general ridge patterns that permit them to be systematically classified into three groups: L.A.W. Loop: ridge lines enter from one side of the pattern and curve around to

exit from the same side of the pattern 60-65% Ulnar loop: open towards little finger Radial loop: open towards thumb Delta: ridge point closest to area of divergence. All Loops have one delta

Whorl: ridge patterns that are generally rounded or circular in shape and have at least two deltas 30-35% Four groups: Plain, central pocket loop, double loop, and accidental

Arch: ridge lines that enter the print from one side and flow out the other side ~5% Plain and tented

Loop pattern.

All loops must have one delta, which is the ridge point at or directly in front of the point where two ridge lines (type lines) diverge.

Whorl patterns.

A plain whorl and a central pocket loop have at least one ridge that makes a complete circuit. If an imaginary line drawn between the two deltas within these patterns

touches any of the circular ridges, the pattern is a plain whorl. If no such ridge is touched, the pattern is a central pocket loop.

The double loop is made up of two loops combined.

An accidental either contains two or more patterns, or is a pattern not covered by the other categories. Hence, an accidental may consist of a combination loop and plain whorl or loop and tented arch.

Arch patterns.

The plain arch is formed by ridges entering from one side of the print, rising and falling, and exiting on the opposite side (like a wave).

The tented arch is similar to the plain arch except that instead of rising smoothly at the center, there is a sharp upthrust or spike, or the ridges meet at an angle that is less than 90 degrees.

Arches do not have type lines, deltas, or cores.

Bifurcation

Ridge ending

Short ridge

Ridge crossing

Enclosure

ACE-V methodology

Analysis

• Examination of Unknown

Comparison

• Compare Unknown to Known Prints

Evaluate

• Consider prints in totality• Compare entire hand at once

Verificatio

n

• Second analyst reviews hypothesis formed during ACE process

ACE-V: Comparison

Must compare the questioned print at (3) levels.

Level 1 encompasses the general ridge flow and pattern configuration.

Level 2 includes locating and comparing ridge characteristics or minutiae.

Level 3 includes the examination and location of ridge pores, breaks, creases, scars, and other permanent minutiae.

DefinitionsVisible prints: prints made by fingers

touching a surface after the ridges have been in contact with colored material such as blood, paint, grease or ink.

Plastic prints: ridge impressions left on a soft material such as putty, wax, soap, or dust

Latent (invisible) prints: impressions caused by the transfer of body perspiration or oils present on finger ridges to the surface of an object

Drag picture to placeholder or click icon to add

For left hand

Henry Classification SystemEnglishman Sir Edward Richard Henry system

proposed in 1897 and adopted by Scotland Yard in 1901

Converted ridge patterns on all ten fingers into a series of letters and numbers arranged in the form of a fraction. Modified, as original system only could be used for

up to 100,000 unique fingerprints

Primary Classification10 finger Identification System is part of the

Henry System

Still part of initial FBI system

Used to give a suspect candidate pool. Example:R. Index R. Ring L. Thumb L. Middle

L. Little

R. Thumb R. Middle R. Little L. IndexL. Ring

16 + 0 + 0 +0 + 0 + 1 = 17

0 + 8 + 0 + 0 + 0 + 1 = 8

Primary Classification

If a whorl pattern is found on any finger of the first pair, it is assigned a value of 16; on the second pair, an 8; on the third pair, a 4; on the second pair, a 2; and on the last pair, a 1.

Any finger having a loop or arch is assigned a 0.

After values for all 10 fingers are obtained, they are totaled, and a 1 is added to both the numerator and denominator.

The fraction thus obtained is the primary classification.

Primary ClassificationA fingerprint classification system

cannot in itself unequivocally identify an individual; it will merely provide the fingerprint examiner with a number of candidates, all of whom have an indistinguishable set of prints in the system’s file.

Automated SystemsComputer approach replaced manual

approach ca. 1970.

AFIS: Automated Fingerprint Identification Systems

In AFIS, computers scan and digitally encode fingerprints for rapid fingerprinting archive searchesData encoded so that the ridges at points of

termination and branching of ridges into two ridges are made into digital minutiae

Importance of AFIS

Speed

Larger, less cumbersome catalogue

Ability to identify single, latent prints more readily in no-suspect cases

Able to digitally enhance and filter out imperfections on latent prints

However, some latent prints are not really suited for searching using a computer databaseStill require manual printing of the suspect and visual

comparison to the prints lifted from the crime scene

How to identify print locationsWhere would you look for prints

when first processing a crime scene?

Processing FingerprintsHard, non-absorbent surfaces

Develop with powder, SuperGlue, etc

Soft, porous surfaces Involve chemicals, e.g. ninhydrin

Reflected UV Imaging System (RUVIS) Locate prints on most non absorbent surfaces without the aid

of chemical or powder treatments

Powder: grey (aluminum) or black (carbon), whichever color is best for visualizing prints on the surface material Also magnetic or fluorescent powders

Iodine FumingHelp visualize latent prints

Iodine, when heated, sublimates (i.e. phase changes from solid to vapor without becoming a liquid)

After heating, the iodine vapor will chemically react with compounds in the latent print and make it visible Not a permanent visualization process unless fixed Fixation of print with 1% aqueous starch solution

Print will turn blue and will be “fixed” for several weeks to several months

Ninhydrin ProcessingChemically reacts with amino acids (in

perspiration) to form a purple-blue color

Sprayed onto a porous surface using an aerosoloizer

Prints start to develop within an hour, but may take up to 24-48 hours

Process can be accelerated if heat is used (80-100 C)

Ninhydrin Test: Ruhemann’s purple = Positive for Amino Acids

1,2,3-triketo-hydrindene hydrate

Physical developer

Silver nitrate based liquid reagent

Newer technique gaining in popularity

Particularly on porous materials that may have been wet at one time

Treatment Order on Porous Surfaces Iodine fuming

Ninhydrin visualization

Physical Developer

SuperGlue FumingOn non porous surfaces such as metals,

electrical tape, leather, and plastic pages or bags

98-99% Cyanoacrylate ester with sodium hydroxide

Chemical interacts with and visualizes latent print

Develop within six hours as fumes from glue adhere to print

Print will appear white

Argon Ion LaserCertain compounds in fingerprints (in

perspiration) will exhibit natural fluorescence with excited with laser light

Easier to see with naked eye or photography

Ar-ion laser: blue green light

Need to use laser safety goggles to filter out light

Also can use secondary fluorescent dyes – i.e. chemically-induced fluorescence: Rhodamine 6G or zinc chloride

Rules for visible fingerprintsFingerprints found in conjunction

with fluids (e.g. DNA (blood, saliva, etc) should be transported to the lab for processing, with no visualization methods being used at the crime scene

Preservation of Prints

Preserve print visuallyPhotography:

fixed focus of the printgeneral location

Preserve print physically If small, transport entire area that include print If large, and on immovable objects, “lift” the print

Lift using something like scotch tapeAdhere tape to a cardboard-type backing that

provides a background contrast with the powder

Digital ImagingPrint processed digitally (pixellation)

on grey-scale vs. color scale0 (black) to 255 (white)

Resolution: degree of detail that can be seen in an image. Larger the number of pixels, the better the resolution

FFT: frequency Fourier Transform analyzes the frequency of the patterns that may be interfering with the digital processing and can be used to enhance the image

Houston Cold Case

Diane Maxwell Jackson, abducted, raped, strangled, and stabbed to death on December 14, 1969

No suspects initially identified

Brother campaigned to have case reopened ca. 1989

Houston PD and TX Dept. of Public Safety: no possible matches

July 2003: 20 possible matches with IAFIS

James Ray Davis number one candidate for a match

Previous crimes, but they needed a confession in order to prosecute him.

Why did they need his confession?

Randy Scott: Sept. 11, 2001

Basics on How to Compare Fingerprintshttps://www.youtube.com/watch?

v=IrpTqKkgygA