Lecture 11: fingerprints and other impressions

Sir William J. Herschelco

llected the first fingerprint in 1858 from India

Dr. Henry Faulds

published first paper on fingerprinting in Nature, 1880

Sir Francis Galton

father of fingerprinting

Sir Edward Richard Henry

• developed Henry’s fingerprint classification system in 1897

• Scotland Yard adopted Henry’s system in 1901 as an official method for criminal identification

alphonse Bertillon:

anthropometry or Bertillon system in 1883

1903: anthropometry to fingerprinting

• will and william west both at Ft. Leavenworth prison

• very similar bertillon measurements

• fingerprints identified the men

Fingerprinting in the USA

• 1901: first systematic and official use by NY city civil service commision

• 1924: FBI fingerprint repository established. FBI have largest collection of fingerprints

• 1990s: automated fingerproint identification systems (AFIS) begin widespread use around the country

• 1999: FBI started integrated AFIS (IAFIS) at clarksburg, WV

Principles of Fingerprinting

1. a fingerprint is unique (individualized characteristics)

2. fingerprints are permanent

3. fingerprints have general ridge patterns that can be classified (class characteristics)

A fingerprint is unique

can have multiple characteristics including:

• ridge ending

• island or short ridge

• bridge

• eye or enclosure

• delta

• bifurcation or fork

• dot

• spur

• double bifurcation

• trifurcation

Fingerprints are permanent

• develop on fetus pre-birth (10-14 weeks)

• the dermal papillae is responsible for determing the form and pattern of the ridges on the surface of the skin

general ridge patterns: L.A.W.

1. loops (65% of all fingerprints)

2. arches (5% of all fingerprints)

3. whorls (30% of all fingerprints)

Loop

1. one or more ridge enter and exit from the same side

2. have on delta

3. two types, ulnar and radial

ulnar loops

opens toward the little finger

radial loop

opens toward the thumb

type lines

2 innermost ridges which run parallel and then diverge and surrounds the pattern area

core

approx. the center of the pattern

arch

1. looks like a bell curve grading scale

2. enter on one side and ext on the other side

3. no delta or core

4. two types: plain and tented

plain arch

looks like a wave

tented arch

like plain arch, but ridges meet at angle <90 degrees.

whorl

1. rounded or circular shape

2. have minimum of two deltas and a core

3. four types: plain, central pocket loop, double loop, accidental

plain whorl

an imaginary line drawn between the two deltas touches any of the spiral ridges

central pocket loop whorl

an imaginary line drawn between the two deltas does not touch any of the spiral ridges

double loop whorl

made of of two loops combined into one

accidental

have two or more patterns (excluding plain arch) or no known pattern

steps to identify and individualize ridges: ACE-V process

1. analysis: determine distortion and value minutiae

2. comparison: compare the questioned print at (3) levels

   a. level 1: general ridge flow and patterns, NOT sufficient for individualization, can be used for exclusion

   b. Level 2: compare ridge characteristics, sufficient for individualization

   c. level 3: ridge details such as pores, breaks, scars, creases etc.

3. evaluation: identification or exclusion or inconclusive

4. verification: independent examination by second examiner

The henry-FBI classification system

• the system is subdivided into primary, secondary, sub-secondary, final, major, and key

• the primary classification is based on the value of whorl patterns present

• each finger is given a point value

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

AFIS/IAFIS: automated fingerprint identification system

1. a computer system for storing and retrieving fingerprints

2. began in the early 1970s to:

   search large files for a set of prints taken from an individual

   compare a single print, usually a latent print developed from a crime scene

3. by 1990s most large jurisdictions had their own system in place

Other facts about AFIS system

• the problem with AFIS- a person’s fingerprints may be in one afis but not in others

• 1991: FBI established IAFIS which is a national database of all 10-print cards from all over the country

• open for 24 hours and 365 days a year

• contain /70 million criminals and 34 million civilfingerprints

• response time is about 27 minutes

patent or visible prints

made when friction ridge comes into contact with colored materials such as blood, paint, ink, grease, etc.

plastic prints

ridge impression on soft materials such as soap, wax, dust, clay, etc.

latent/invisible prints

ridge impression that are produced by transfer of sweat (98-99%) and oils on a surface

visualization of latent prints method: hard/non absorbent surface, powder method

• black powder made up of charcoal; good for light surface

• gray powder: made up of aluminum dust; good for dark surface

• magnetic powder: good for leather, rough plastics,; non-destructive

• flourescent powders: flourescein (UV light)

iodine fuming for latent prints: soft or porous surface

• the oldest chemical method

• fumes most probably react with oils and fats

• must be photographed immediately

• can be stored for several months after covering with cellophane tape

ninhydrin for soft of porous surfaces

• spray ninhydrin on the surface

• print appear within an hour after application

• ninhydrin reacts with the amino acids and produce a dark purple color

• method of choice because of sensitivity and easy to use

silver nitrate/physical developer: soft porous surfaces

• work even if ninhydrin fails

• washes away any trance of protein

• order of application: iodine-ninhydrin-physical developer

superglue fumes: non-pourous surface

• 98-99% cyanoacrylate ester

• when heated cyanoacrylate ester band produces fumes

• good for small closed areas such as car’s interior and for non-porous surface

photography and lifting

• the camera is fitted with an attachment to give ~ 1:1 photo of fingerprint

• an adhesive sheet is used to “lift” the powdered print off the can.

other impressions

impressions other than fingerprints and firearm and toolmarks encountered at a crime scene include, but are not limited

• shoe prints

• tire marks

• fabric impressions

they can be left on a variiety of surfaces in a variety of scenes.

preserving impressions

• the primary consideration collecting impressions at the crime scene is the preservation of the impression or its reproduction for later examination in the crime laboratory

• before an impression is moved or handled, several photographs should be taken from various angles

• it is preferable to use the original impression for comparison

lifting impressions

• if an impression cannot be taken to the laboratory, it may be preserved in a manner similar to lifting a fingerprint

• especially useful for impressions in light deposits of dust or dirt .

electrostatic lifting

• a sheet of mylar film is placed over the impression

• the electrode of a high-voltage electrostatic unit is attached to the mylar sheet, and the ground electrode is attached to the earth plate

• the electrostatic charge applied causing the dust to transfer to the lifting film

casting impressions

• class 1 dental stone is generally used for casting shoe and tire impressions

• snow impression wax is an aerosol used for casting impressions in snow

• chemicals can be also be used to enhance shoe impressions in blood: luminal, bromohphenol blue

comparing impressions

• value of the impression is determined by the number of class and individual characteristics that the examiner finds

• size, shape, or design may permit the conclusion that the impression could have exclude other possible sources from having the same class characteristics

• more significant is the existence of individual characteristics arising out of wear, cuts, gougges, or other damage

• a suffiient number or the uniqueness of such points of comparison supports a finding that both the evidence and test impressions originated from only one source

• human bite marks on skin and foodstuffs have been important items of evidence for convicting defendants in a number of homicide and rape cases in recent years