NotesCh. 14 Fingerprints

I. History of Fingerprints

• Police have always looked for a foolproof method of human identification.

• 1st system: Bertillon 1883 called anthropometry

A. Early Use of Fingerprints1. Chinese: ~1000 B.C. used F.P. to sign legal

documents

2. 1880: Fauld and Herschel suggested that fingerprints are useful for ID criminals

B. Early Classification of Fingerprints1. Galton, in 1892, published Finger Prints

a. Demonstrated no 2 F.P. are identicalb. Showed individuals F.P. remain

unchanged in lifec. Proposed 3 F.P. categories

1. Loops (~60%)2. Whorls (~30-35%)3. Arches (~5-10%)

2. Development of Classification Systema. Dr. Juan Vucetich-Argentina

1891 (still used in most Spanish speaking countries today)

b. Sir Edward Henry-England 1897 (used in U.S., England, etc.)

C. Adoption of Fingerprints1. 1901-New York City adopted F.P.2. 1903-Prison “Twins”

-2 criminals looked and measured identically-fingerprints were very different

3. 1904-World’s Fair: Police trained by Scotland Yard

II. Fundamental Principles of F.P.A. First Principle:

-A F.P. is an individual characteristic-No two fingers have yet been found to possess identical prints

*Currently 60 million F.P. in FBI database

1. I.D. of fingerprints based on Ridge Characteristics (a.k.a. minutaie)

2. Ridge CharacteristicsA. bifurcationB. ridge endingC. ridge islandD. enclosureE. short ridgeF. bridgeG. CrossoverH. Spur (hook)

Let’s practice!

• Take out a pen (blue or black ink) and clear everything else off your desk.

• Balloon prints

B. Second Principle1. A fingerprint remains unchanged during an individuals lifetime

a. Fingerprints develop at 3 months gestation. b. Many criminals have tried to alter/eliminate them.

2. Shape of dermal papillae determines form and pattern of ridges

• Papillae are cells that separate epidermis from dermis.

C. Third Principle• Fingerprints have general ridge patterns that permit them to be systematically classified1.General patterns

A. loops (~60-65% of population)1. ulnar loop 2. radial loop

B. whorls (~30-35%)1. plain whorl 2. central pocket whorl3. accidental whorl 4. double loop whorl

C. arches (~5%)1. plain arch 2. tented arch

III. Classification of Fingerprints

A. Fingerprint Vocab 1. Core: center of the fingerprint 2. Delta: triangular area

B. Specific Types of Fingerprints• Two Types of ARCHES

Arch-all lines enter and exit from opposite sides of finger

2. Tented Arch-drastic spike

1. Plain Arch-rolling hill

• 2 Types of Loops

Must know which hand you are looking at to determine!!

Loop-only one delta; at least one ridge line enters and exits same side of print

• 4 Types of Whorls

1. Plain Whorl-line between deltas intersects circles

2. Central Pocket Loop Whorl-line btwn deltas does not intersect full circles;

whorl-2 deltas; at least one ridge line does not exit finger

Practice• Plain whorl or central pocket loop whorl?

ANS: Central pocket loop whorl

Practice• Plain whorl or central pocket loop whorl?

ANS: Plain whorl

More Whorls3. Double loop whorl: looks like

yin yang4. Accidental whorl-

characterized by 3 deltas; frowny face

Accidental Whorls: 2 or more types of prints

More Examples

Practice• Double loop whorl or accidental whorl?

ANS: double loop whorl

Practice

• Double loop whorl or accidental whorl?

ANS: accidental whorl

Let’s practice!

• Please take your Unit 2 classwork paper.

• Date: 9/22/14• Title: WS: Classification of FP #2

C. Fingerprint Classification Code1. Every print is given a code after it enters the F.P. database2. 1st classification step called the primary classification 3. Code is based on presence or absence of whorl4. Approximately 25% of the population falls into the 1/1 category (they do not have any whorls)

Fraction =R.Index R. Ring L. Thumb L. Middle L. Little +1R.Thumb R.Mid R. Little L. Index L. Ring +1 (16) (8) (4) (2) (1)

Example #1:• Suspect F.P.

Finger Left Right

Thumb Arch Loop

Index Loop Loop

Middle Whorl Arch

Ring Loop Loop

Little Arch Whorl

0 + 0 +

0 0

++

20

00

++

04

11

= 35

Example #2Finger Left Right

Thumb Arch Whorl

Index Loop Loop

Middle Loop Arch

Ring Loop Whorl

Little Arch Arch

• Suspect F.P.

0 + 16 +

8 0

++

00

00

++

00

11

= 917

**Do not reduce fraction: 2/4 stays as 2/4

Practice

• Find your own classification code.• Determine your partner’s classification code. • Compare your answers.

Take out Unit 2 Classwork paper.Date: 9/23/14Title: FP Code Practice

D. AFIS• AFIS : Automated Fingerprint Identification

System• FBI has largest• Some cities, counties, states have their own

that may or may not link to FBI• Converts image of fingerprint into digital scan

with reference points to ridge endings and bifurcations

III. 3 Types of Crime Scene Prints1. Visible-can be seen by naked eye

Ex: prints left in blood, paint, dust, grease, ink

2. Plastic-occurs when ridge impressions are left in soft material

Ex: prints left in wax, play-doh, soap, puddy3. Latent (Invisible)-not seen by naked eye; caused

by a transfer of oils onto surface

IV. Methods for Developing Latent Prints• Super Glue Fuming-nonporous materials• Dusting-nonporous materials

• Iodine Fuming-porous materials• Ninhydrin-porous materials• Physical Developer-porous materials

V. Locating Fingerprints

• Visible and plastic easy to see• Latent: RUVIS (reflected ultraviolet imaging

system)– aims UV light at a surface suspected of having

prints– Light is converted into visible light

VI. Proper Collection of F.P.

• Step 1: Location documented, object photographed

• Step 2: – Small Object: taken back to lab, F.P. developed

there– Large Object: F.P. developed and lifted at crime

scene