GENERAL FINGERPRINT FACTS Three Fundamental Principles of Fingerprints 1. A fingerprint is an individual characteristic. No fingers have identical ridge characteristics 2. A fingerprint will remain unchanged during an individualʼs lifetime. 3. Fingerprints have general ridge patterns which make it possible to systematically classify them. What Causes Fingerprint Patterns? Human skin is made up of two layers: the epidermis (where fingerprint ridges are found) and the dermis (where sweat glands are found). Each ridge of the epidermis is dotted with sweat pores. Sweat glands produce a water-based oil solution that is released from each sweat pore and coats the ridges of your epidermis. The ridges retain the sweat solution such that when the finger makes contact with any surface, residue is left behind. Types of Fingerprint Evidence 1. VISIBLE: 2. LATENT: 3. PHYSICAL: Fingerprint Terminology 1. TYPE LINES: 2. DELTA: 3. CORE: Fingerprint Patterns LOOPS Approximately 60% of people exhibit this pattern. This pattern has ridges that enter from one side of the finger, recurve, touch or pass an imaginary line between the Delta and Core and tend to exit the same side as the ridge entry. There are two sub-classes. ULNAR VS RADIAL LOOPS " " " " " " " To determine if you have an ulnar or radial loop there are three things to remember: 1. You have two bones in your lower arm: the ulna (lines up with your pinky) & the radius (lines up with your thumb) 2. The bone which the loop begins and ends at determines which type of loop it is (this is called the “road test”) 3. You must know which hand right or left - the print came from. The loops reverse depending on which hand theyʼre from. Radial loop (right hand) Ulnar loop (right hand) WHORLS Approximately 34% of people exhibit this pattern. Lines form concentric circles, whirlpools or spirals. Sub-classes include plain, central pocket, double loop & accidental. PLAIN WHORLS " " " " " " " The ridges make a turn of one complete circuit and, therefore, circular or spiral in shape. They have two deltas. This is the simplest and most common of whorl fingerprint. CENTRAL POCKET WHORLS " " " " " " " This fingerprint pattern recurves a second time forming an inner pocket (whorl) within an outer loop. It has a minimum of two deltas and type lines. Is sometimes known as a Peacockʼs Eye, due to itʼs similarity to the eye pattern on a male peacock feather. DOUBLE LOOP WHORLS " " " " " " There are two separate loop formations which attempt to wrap around each other. There are two entirely separate and distinct sets of deltas. ACCIDENTAL WHORLS A combination of two different types of patterns (with the exception of Plain Arches). Have two or more deltas. Combinations can include: - Loop and a whorl - Loop and a tented arch - Loop and central pocket loop - double loop and central pocket loop ARCHES Approximately 6% of people exhibit this pattern. Lines cross smoothly or upthrust at the center of the finger. Sub-classes include plain and tented. PLAIN ARCH Simplest of all fingerprint patterns. It is formed by ridges entering from one side of the print and exiting on the opposite side. These ridges tend to rise in the center of the pattern, forming a wave-like pattern. TENTED ARCH Starts on side of the finger and flows out in a similar pattern to that of a plain arch. The difference lies in the ridges in the center, which are not continuous (they adjoin each other, converge and thrust upward giving the impression of a pitched tent). OVERALL FINGERPRINT FREQUENCY Ulnar Loop - 56% Radial Loop - 4% Plain Whorl - 24% Central Pocket Whorl - 4% Double Loop Whorl - 4% Accidental Whorl - 1% Plain Arch - 4% Tented Arch - 2% 4% 56% 24% 4% 4% 1% 4% 2% TEST YOUR KNOWLEDGE NAME: 1. Which general pattern requires that you know which hand it came from before you can identify it? 2. The radial bone is aligned with which finger in the hand? 3. Which two sub-classified patterns are made up of two or more fingerprint patterns? 4. Describe what a delta is? How can you identify it? 5. Fingerprints are located on which layer of the skin? ______________________________________________________________________ Identify the specific type of fingerprint pattern for each of the following. Assume that these come from the RIGHT THUMB of the suspect.