Module 7.4: Dactyloscopy (Fingerprint Classification Systems)

I. Fundamental Principles of Fingerprint Science

The entire science of Dactyloscopy rests on three core principles, often called the "dogmas" of fingerprinting.

1. Principle of Individuality (Uniqueness)

No two fingerprints have ever been found to be exactly alike.

The basis for this principle is the study of ridge characteristics (also called minutiae or Galton's details). These are the fine details in the friction ridges, such as:

Ridge Ending: A ridge that abruptly stops.
Bifurcation: A single ridge that splits into two.
Dot or Island: A very short ridge.
Enclosure: A ridge that splits and quickly reforms.

While two people might have the same general fingerprint pattern (e.g., a loop), the specific arrangement and location of their ridge characteristics will always be different. There is no known rate of duplication.

Sa madaling salita, ang Principle of Individuality ay nangangahulugang WALANG dalawang fingerprints na magkapareho - kahit kambal pa kayo! Ang basehan nito ay yung mga maliit na detalye sa ridges na tinatawag na minutiae o Galton's details. Halimbawa: ridge ending (biglang tumigil ang ridge), bifurcation (yung ridge na naghahati sa dalawa - parang sangay ng puno), dot (napakaikli lang na ridge - parang tuldok), at enclosure (parang island na bumabalik agad). Kahit may parehong pattern (halimbawa parehong loop), ang arrangement ng minutiae ay laging iba. Kaya unique talaga ang bawat tao!

2. Principle of Permanency (Immutability)

The friction ridge patterns of the fingers are formed during fetal development and remain unchanged throughout an individual's life until decomposition after death.

Formation: Fingerprints develop in the womb at around the 3rd to 4th month of fetal life.
Durability: The patterns are formed on the dermal papillae, a layer of cells between the outer skin (epidermis) and the inner skin (dermis). As long as the dermal papillae are not damaged, the fingerprint will always grow back in the exact same pattern, even after superficial cuts, burns, or scrapes to the epidermis.
Scars: A deep cut or burn that damages the dermal papillae will result in a permanent scar, which itself becomes a unique and permanent feature of the fingerprint.

Ang Principle of Permanency ay nangangahulugang ang fingerprint pattern mo ay PERMANENT - hindi magbabago mula pagsilang hanggang kamatayan! Nabuo na yan sa tiyan ng nanay mo (3rd-4th month ng pregnancy). Ang pattern ay naka-embed sa dermal papillae - yung layer ng cells sa pagitan ng epidermis (outer skin) at dermis (inner skin). Kaya kahit magka-gasgas ka, ma-burn ng mababaw, o may superficial cut - tutubo ulit yan sa exact same pattern! Pero pag MALALIM ang sugat na umabot sa dermal papillae, mag-iwan ng permanent scar - na nagiging unique feature pa rin ng fingerprint mo. Kaya walang takas ang kriminal kahit subukan niyang alisin ang fingerprints - babalik pa rin, or mag-iwan ng scar na mas unique pa!

3. Principle of Infallibility

Because fingerprints are unique and permanent, they are a reliable and infallible means of personal identification.

This principle states that fingerprints cannot be forged or faked. While a criminal might try to alter their fingerprints, the attempt will almost always leave behind tell-tale signs (scars) that make the print even more unique. The courts have universally accepted the reliability of fingerprint evidence for over 100 years.

Board Exam Tip: You must be able to state and explain these three principles. They are the absolute foundation of fingerprint science.

III. The Three Basic Fingerprint Patterns

All fingerprint patterns can be classified into one of three large general groups.

A. The Arch (Approx. 5% of all fingerprints)

In the arch pattern, the ridges enter from one side of the finger, rise in the middle, and exit on the opposite side, forming a wave-like pattern.
Arches have NO delta and NO core.
Types:
- Plain Arch: The ridges rise smoothly in the center.
- Tented Arch: The ridges in the center have a sharp upward thrust, spike, or "tent-like" shape.

Isipin mo ang ARCH na parang bundok o tulay (bridge) - pumapasok ang ridges sa isang side, umaakyat sa gitna, tapos bumababa sa kabilang side. Walang delta at walang core ang arch - yan ang pagkakakilanlan niya! Ito ang PINAKA-RARE na pattern - mga 5% lang ng population ang may ganito! May dalawang klase: (1) Plain Arch - smooth lang yung pag-akyat sa gitna, parang gentle slope; (2) Tented Arch - may sharp upward thrust sa gitna, parang matatarik na tent o spike. Para maalala: ARCH = RARE (5% lang)!

B. The Loop (Approx. 60-65% of all fingerprints)

In the loop pattern, one or more ridges enter from one side, recurve (loop around), and exit on the same side they entered.
A loop has ONE delta and ONE core.
Types (based on the direction the loop opens):
- Ulnar Loop: The loop opens towards the ulna bone (the "pinky" side of the hand).
- Radial Loop: The loop opens towards the radius bone (the "thumb" side of the hand).
Ridge Counting: The process of counting the number of ridges that cross an imaginary line drawn between the delta and the core. This is a key step in classification.

Ang LOOP ay ito ang MOST COMMON na pattern - 60-65% ng tao ay may loop! Isipin mo na parang hairpin turn o U-turn - pumapasok ang ridges, biglang loop around (balik), tapos lumalabas sa SAME SIDE kung saan sila pumasok. May ONE delta at ONE core ang loop. May dalawang uri: (1) Ulnar Loop - ang opening ay patungo sa ulna bone (pinky side) - ito ang mas common; (2) Radial Loop - ang opening ay patungo sa radius bone (thumb side). Para maalala kung ulnar o radial: Ulnar = U-turn sa pinky side! Ang ridge counting ay bilang ng ridges na tumatawid sa imaginary line between delta and core - importante ito sa classification!

Board Exam Tip: Memorize: LOOP = MOST COMMON (60-65%). Has 1 delta + 1 core. Ulnar opens to pinky, Radial opens to thumb!

C. The Whorl (Approx. 30-35% of all fingerprints)

The whorl pattern consists of one or more ridges that make a complete circuit, often in a spiral or circular shape.
A whorl has TWO or more deltas and ONE core.
Types:
- Plain Whorl: Consists of one or more ridges which make a complete circuit, with two deltas, between which an imaginary line is drawn and at least one recurving ridge within the inner pattern area is cut or touched.
- Central Pocket Loop Whorl: A hybrid pattern that has features of both a loop and a whorl. It has two deltas, but one of them is much closer to the core, and an imaginary line drawn between the two deltas does not touch or cross any of the recurving ridges.
- Double Loop Whorl: Consists of two separate and distinct loop formations with two separate and distinct shoulders and two deltas. (The "S" shape).
- Accidental Whorl: A pattern that combines two or more different pattern types (excluding the plain arch) or a pattern that does not fit into any other definition.
Ridge Tracing: The process of following the ridge that emanates from the lower side of the left delta until it reaches the point opposite the right delta. The number of intervening ridges determines if the whorl is an Inner (I), Meeting (M), or Outer (O) whorl.

Ang WHORL ay pangalawang most common - 30-35% ng tao. Isipin mo na parang spiral o bilog - yung ridges ay gumagawa ng complete circuit (buong ikot). May TWO or MORE deltas at ONE core ang whorl - yan ang pagkakakilanlan niya! May apat na uri: (1) Plain Whorl - simple spiral/circular pattern lang; (2) Central Pocket Loop Whorl - parang hybrid ng loop at whorl, may dalawang delta pero isa ay malapit sa core; (3) Double Loop Whorl - dalawang loop formations na magkasama, parang letter "S"; (4) Accidental Whorl - combination ng iba't ibang patterns o hindi pasok sa ibang definitions (catch-all category). Ang ridge tracing ay process ng pagsunod sa ridge mula left delta hanggang right delta - para malaman kung Inner (I), Meeting (M), o Outer (O) ang whorl.

Board Exam Tip: Easy way to remember: ARCH = 0 deltas (5%), LOOP = 1 delta (60-65%), WHORL = 2+ deltas (30-35%). Whorl types: Plain, Central Pocket Loop, Double Loop, Accidental!

Summary of Pattern Characteristics

Pattern	Deltas	Core	Prevalence
Arch	0	0	~5%
Loop	1	1	~60-65%
Whorl	2 or more	1	~30-35%

IV. Fingerprint Classification

Definition: Fingerprint classification is a system of sorting and filing fingerprint cards based on their patterns. Its purpose is to allow a set of fingerprints (a "ten-print card") to be quickly searched for and retrieved from a large file.

The Henry Classification System: Developed by Sir Edward Henry in the late 19th century, this is the system upon which most modern fingerprint filing systems are based. It is the foundation of the manual, pre-computerized method of fingerprint searching.
Primary Classification: The first step in the Henry system. It is a numerical representation of the presence of whorl patterns.
- Each finger is assigned a numerical value if it has a whorl pattern. Fingers with arches or loops are given a value of zero.
- The values for the even-numbered fingers (2, 4, 6, 8, 10) go in the numerator, and the values for the odd-numbered fingers (1, 3, 5, 7, 9) go in the denominator.
- A constant of 1 is added to both the numerator and denominator.
- This results in a fraction (e.g., 1/1, 17/2, 32/32), which represents the primary classification. This allows all cards with whorls to be grouped together, separate from cards that have no whorls (which will always have a primary classification of 1/1).
Other Classifications: The Henry system includes several other sub-classifications (Secondary, Sub-secondary, Major, Final, Key) that further narrow down the search by looking at specific patterns on the index fingers, thumbs, etc.

Modern Systems (AFIS): Today, manual classification is largely obsolete for searching. The Automated Fingerprint Identification System (AFIS) is a computerized database that can search through millions of prints in minutes. However, a knowledge of the basic classification rules is still essential for fingerprint examiners and is a major part of the board exam.

Ngayon, ang AFIS (Automated Fingerprint Identification System) na ang ginagamit - ito ay computerized system na kaya mag-search ng millions of fingerprints sa loob lang ng ilang minuto! Pero importante pa rin na marunong ka ng manual classification (Henry System) kasi yan ay malaking parte ng board exam. Ang AFIS ay tulad ng Google ng fingerprints - i-scan mo lang ang unknown print, tapos mag-search ang computer sa database at lalabas ang mga possible matches. Ang PNP Crime Laboratory ay gumagamit ng AFIS para sa mga investigations!

Board Exam Tip: AFIS is the modern automated system, but Henry Classification System is still tested heavily in the PRC exam. Master both!

Introduction

Dactyloscopy is the science of personal identification through the study of fingerprints. For over a century, it has been the most relied-upon and legally accepted method for identifying individuals in criminal investigations. The "inked" fingerprint is a powerful biometric signature that is unique to each person and remains unchanged throughout their life. This module will cover the fundamental principles of fingerprint science, the classification of fingerprint patterns, and the basic structure of the Henry Classification System, which forms the basis for fingerprint filing and searching.

Key Learning Objectives:

State and explain the three fundamental principles of fingerprint science (Individuality, Permanency, Infallibility).
Identify and describe the three basic fingerprint patterns: Arch, Loop, and Whorl.
Define key fingerprint terminology, including friction ridges, delta, and core.
Understand the concept of ridge counting and ridge tracing.
Explain the purpose of fingerprint classification.

II. Friction Skin and Basic Terminology

Friction Skin (Papillary Skin): The specialized skin found on the palms of the hands and soles of the feet, characterized by a series of ridges and furrows. Its biological purpose is to provide friction for gripping.
Friction Ridges: The raised strips of skin on the fingers and palms.
Furrows: The valleys or depressions between the friction ridges.

Key Focal Points for Classification:

Pattern Area: The part of a fingerprint where the core, delta, and ridges needed for classification are located.
Delta: The point on a ridge at or nearest to the point of divergence of two typelines. It is a triangular-shaped feature.
Core: The approximate center of the fingerprint pattern.

| Arch | 0 | 0 | ~5% | | Loop | 1 | 1 | ~60-65% | | Whorl | 2 or more | 1 | ~30-35% |

Conclusion

Dactyloscopy remains the gold standard of personal identification. Its power lies in its three fundamental principles: fingerprints are unique, permanent, and therefore infallible. By understanding the basic patterns—Arch, Loop, and Whorl—and the principles of classification, the student of criminalistics can appreciate how a simple set of inked impressions on a card can be systematically organized, searched, and used to identify a suspect with absolute certainty.