FINGER PRINTS

Dr. Swaroop Vedanand

Skin that is found on the fingers, palms, toes and sole is not smooth, but rather contains tiny raised lines (friction ridges) that allow to grasp and hold on to objects. These series of lines from both ridges and grooves that take on a distinct and individually unique pattern.

The ridge patterns differ from individual to individual, also from finger to finger in every individual.

They never change during the life of an individual.

These characteristics of uniqueness & permanence of fingerprints offer the most successful means of identifying a person

Minute pores found on the tops of the friction ridges are constantly emitting perspiration and oil that clings to the surface of the of the ridges.

When fingertips come into contact with a surface, perspiration is transferred to that surface. These imprints of friction ridge patterns are termed as fingerprints.

Historical Development

In 1788, J.C.A.Mayer of Germany proposed the theory that friction ridges is never duplicated in two individuals.

In 1892, Sir Francis Galton of Britain established that no two fingerprints were alike and also developed a system for the classification of finger prints.

In 1858, British administrator in Bengal Sir William Herschel started the practice of recording hand prints of natives on contracts to prevent impersonation.

Sir Edward Henry, Inspector General of Police in Bengal succeeded in developing a more workable system of classification which was first adopted in in India in 1887 and later in Scotland Yard in London in 1901.

Significant contribution made by two Bengal Police Officers namely

Khan Bahadur Azizul Haque for Henry ten-digit classification system and

Rai Bahadur Hem Chandra Bose for single-digit classification system

The finger Patterns (designs) are mainly divided into four groups

1) Whorls

2) Arches

3) Loops

4) Composite pattern

WHORL

In whorl pattern at least one ridge must re-curve and make a complete circle around the core. The whorl may be spiral, oval or circular.

In Arch pattern, the ridges run from one side of the finger to the other side with out turning back, slightly raising at the center where the curvature looks like an Arch.

ARCHE

LOOP

In loop pattern the ridges enter and exit in the same side of the pattern.

COMPOSITE PATTERNS

Composite pattern means combination of either same or different types of patterns.

Central pocket loop Lateral pocket loop

Twin loop Accidental

Sub ClassificationArches - Plain Arch

Tented Arch

Loops - Radial Loop

Ulnar Loop

Composites - Central Pocket Loop

Twin Loop

Lateral Pocket Loop

Accidental Loop

Ridge Characteristics

Identity of Fingerprint is established by comparing the ridge characteristics.

Ex. Core, Delta (position & distances)

Ridge endings, Bifurcations,

Forks, Enclosures, Islands,

Dots, Short Ridges

Delta Core

Island Dot

Bifurcation Ending of the ridge

Method comparing the fingerprints

Henry’s Ten digit classification system

Henry system assigns a number to each finger where the right thumb is given the number 1 and the left little finger has the number 10. It also assigns a numerical value to fingers that contains whorl pattern.

Finger No : 10 9 8 7 6 1 2 3 4 5

Whorl Value : 1 1 2 2 4 16 16 8 8 4

Primary Classification ratio = 1 + (Sum of even-finger value)

1 + (sum of odd-finger value )

If the Henry classification system were to be used world wide, the world’s population would be divided into 1024 primary groups.

If an individual does not have any whorl patterned fingerprints, he or she has a primary classification ratio of 1:1. Approximately 25% of the population falls in to this category.

Secondary Classification

The secondary classification consists of capital letter symbols for the patterns of the two index fingers, right as numerator and left as denominator.

Five basic patterns :

Arch (A), Tented Arch (T),

Radial Loop (R), Ulnar Loop (U)

Whorl (W) & Composite (W)

Sub-secondary classification

It is represented by symbols that may be I, M or O. These symbols are given to the whorls appearing on the index, middle and ring fingers of the right hand and make up the numerator and the same left fingers for the left hand make up the denominator

Single Digit System / Battley System

Chance prints left at the scene of crime are normally fewer in number. So the Ten digit classification is not suitable for single fingerprint search.

Each finger is classified separately in single fingerprint classification system and further they are subdivided according to general pattern types.

Crime Scene Prints

Crime Scene Prints are of three types

1. Visible prints : by Dirt, ink, paint, blood

2. Plastic prints : on soap, candle, mud, wax, adhesives

etc.

3. Latent prints : These chance prints are latent of invisible

DEVELOPING THE LATENT FINGER PRINTS

By Powder method By Magnetic powder By Fluorescent powder By Iodine fuming method By Silver Nitrate By Nynhydrin