Learning Objectives Know the common ridge characteristics of

Learning Objectives • Know the common ridge characteristics of a fingerprint • List the three major fingerprint patterns and their respective subclasses • Distinguish visible, plastic, and latent fingerprints • Describe the concept of the automated fingerprint identification system (AFIS) • List the techniques for developing latent fingerprints on porous and nonporous objects • Describe the proper procedures for preserving a developed latent fingerprint

History of Fingerprinting • The first systematic attempt at personal identification was devised by a French police expert, Alphonse Bertillion, in 1883. – The Bertillion system relied on a detailed description of the subject, combined with full length and profile photographs and a system of precise body measurements called anthropometry. (See chapter 1) • In 1892 Francis Galton published his classic textbook Finger Prints. – At Galton’s insistence, the British government adopted fingerprinting as a supplement to the Bertillion system. • The next step was the creation of classification systems capable of filing many thousands of prints in a logical and searchable sequence.

History of Fingerprinting • 1891 – Dr. Juan Vucetich, an Argentinian police officer, devised a classification system which has been refined over the years and is still used in most Spanish-speaking countries • 1897 – Sir Edward Henry devised another classification system – Some version of this system is still used today by most Englishspeaking countries including the United States • In 1903, when the Bertillion system could not distinguish between two men (one Will West and the other William West), it was fingerprinting that clearly distinguished them. • After the Will West incident, the use of fingerprinting by the New York City Civil Service Commission in 1901, and the training of American police by Scotland Yard representatives at the 1904 World’s Fair, fingerprinting began to be used in earnest in all major U. S. cities.

Fingerprints Most important category of physical evidence for positive identification or individualization Other Unique surfaces – Ridges of feet – Retinal scans – Palm prints – Ear prints

Fingerprint Principles • Fingerprints are a reproduction of friction skin ridges found on the palm side of the fingers and thumbs. • The basic principles underlying the use of fingerprints in criminal investigations are that: 1) a fingerprint is an individual characteristic because no two fingers have yet been found to possess identical ridge characteristics 2) a fingerprint will remain unchanged during an individual’s lifetime 3) fingerprints have general ridge patterns that permit them to be systematically classified

First Principle of Fingerprints A fingerprint is an individual characteristic. • • • supported by several different theoretical calculations verified by millions of individuals who have had their prints classified over the past 90 years – no two have found to be alike the individuality is determined by a careful study of its ridge characteristics (minutiae)

Comparing Prints • There as many as 150 individual ridge characteristics on the average fingerprint • For the purposes of dactyloscopy, a fingerprint consists of the friction ridge skin of the last joint on each finger from cuticle to cuticle.

Basic Ridge Characteristics The major types are as follows: – Bifurcations: ridges that split into two ridges – Ending Ridge: a simple straight ridge – Dot: a simple dot – Island: a ridge that forks and forms a complete circle, and then becomes a single ridge again Dot Bifurcation Island Ridge Ending

Comparing Prints • If prints are to compare, they will have to reveal characteristics that not only are identical but have the same relative location to one another in a print • How many ridge comparisons are necessary before two fingerprints can be identified as being the same? – number ranging from 8 to 16 have been suggested as being sufficient • 1973: The International Association for Identification concluded that “no valid basis exists for requiring a predetermined minimum number of friction ridge characters which must be present in two impressions in order to establish positive identification” • 1995: members of the international fingerprint community supported the 1973 resolution stated above

Second Principle of Fingerprints A fingerprint will remain unchanged during an individual’s lifetime. Dermal papillae: determines the form and pattern of the ridges on the surface of the skin; develops in the fetal stage and remains unchanged throughout life except to enlarge during growth Each ridge is populated by a single row of pores that are openings for ducts leading from the sweat glands. Perspiration is discharged through these pores and deposited on the skin. When a finger touches a surface, this perspiration along with some oils is transferred to the surface (latent fingerprint).

Second Principle of Fingerprints Although it is impossible to change one’s fingerprints, there has been no lack of effort on the part of some criminals to obscure them. A permanent scar will form if an injury reaches deeply enough into the skin (~1 – 2 mm beneath the surface) damaging the dermal papillae Most notable attempt was that of gangster John Dillinger – tried to destroy his own fingerprints by applying corrosive acid to them

Third Principle of Fingerprints have general characteristic ridge patterns that permit them to be systematically classified. All fingerprints are divided into three classes on the basis of their general pattern: – Loops (most common, 60 – 65%) – Whorls (30 – 35%) – Arches (rarest, ~5%)

LOOPS A loop must have one or more ridges entering from one side of the print, recurving, and exiting from the same side. – – Ulnar Loop: opens toward the little finger Radial Loop: opens toward the thumb Core: center of the pattern Delta: is the area of the pattern where there is a triangulation or a dividing of the ridges.

RADIUS If a loop on a finger opens in the direction of the thumb, it is a radial loop. ULNA If a loop on a finger opens in the direction of the little finger, it is an ulnar loop. This means that a radial loop on a finger on the left hand will open in the opposite direction of a radial loop on a finger of the right hand.

Whorls are divided into 4 distinct groups: plain, central pocket loop, double loop, and accidental. • All whorl patterns have type lines and a minimum of two deltas. • A plain whorl and a central pocket loop have at least one ridge that makes a complete circuit. • The double loop is made up of two loops combined into one fingerprint. • An accidental either contains two or more patterns, or is a pattern not covered by the other categories.

Arches • The plain arch is formed by ridges entering from one side of the print, rising and falling, and exiting on the opposite side (like a wave). • The tented arch is similar to the plain arch except that instead of rising smoothly at the center, there is a sharp up-thrust or spike, or the ridges meet at an angle that is less than 90 degrees. • Arches do not have type lines, deltas, or cores.

Review: Fingerprint Patterns • The major ridges in each finger form a pattern. • There are 3 major pattern types which can be subdivided into a total of 8 patterns: – Loops • Radial Loop • Ulnar Loop – Whorls • Plain Whorl • Double loop Whorl • Central Pocket Loop • Accidental Whorl – Arches • Plain Arch • Tented Arch

Types of Fingerprints Latent: invisible; caused by the perspiration on the ridges of one’s skin coming in contact with a surface Plastic: ridge impressions left on a soft material such as butter, putty, wax, soap or dust Visible: prints made by touching a surface after ridges have come in contact with a colored material such as blood, paint, grease, or ink

Methods of Detecting Fingerprints Locating visible or plastic prints at a crime scene usually presents little trouble for the investigator. The detection of latent prints is a much more difficult task! – Requires techniques that will make the print visible – Method of choice depends on the surface in which the print is located • Prints on hard and nonabsorbent surfaces (glass, mirror, tile) are preferably developed by the application of a powder or Super Glue® treatment • Prints on soft and porous surfaces (papers, cardboard, cloth) generally require treatment with one or more chemicals

Methods of Detecting Fingerprints Fingerprint Powders When applied lightly to a nonabsorbent surface, will readily adhere to perspiration residues and/or deposits of body oils left on the surface. • Black powder: composed of black charcoal; applied on white or lightcolored surfaces • Gray powder: composed of aluminum dust; used on dark colored surfaces • Magnetic-sensitive powder: comes in black and gray; useful on items such as finished leather, shiny magazine covers, and rough plastics • Fluorescent powder: will fluoresce under UV light; may increase sensitivity by 100, 000; best for wooden surfaces (rifle stocks and wood paneling); use color of powder that has a different wavelength than the background; need filtered goggles and color filter on camera for viewing

Methods of Detecting Fingerprints Reflected Ultraviolet Imaging System • Location of prints is often the most difficult aspect of fingerprint examination. • Recent advances in fingerprint technology have lead to the development of an ultraviolet image converter for the purpose of detecting prints. – Device is called the Reflected Ultraviolet Imaging System (RUVIS) • Can locate prints on most nonabsorbent surfaces without the aid of powder or chemical treatment.

Methods of Detecting Fingerprints Iodine fuming is the oldest of the chemical methods used for visualizing latent prints. • Iodine fuming involves heating iodine crystals that cause vapors which combine with latent prints to make them visible. – Iodine prints are not permanent and will fade, making it necessary to photograph the prints immediately. – The reason why this works is not yet fully understood; many believe that the iodine fumes combine with the fatty oils; however, there is also convincing evidence to show that the iodine may actually interact with residual water left on the print from perspiration

Methods of Detecting Fingerprints Cyanoacrylate (Super Glue® fuming) – nonporous surfaces • Super Glue® is approximately 98 to 99 percent cyanoacrylate ester, a chemical that actually interacts with and visualizes a latent fingerprint. • Super Glue fuming can be accomplished by using either a fuming chamber (for up to six hours) or a handheld wand that heats a small cartridge containing cyanoacrylate.

Methods of Detecting Fingerprints Ninhydrin – a chemical reagent used to develop latent fingerprints by reacting with amino acids in perspiration – used for porous items (paper) – reacts with the amino acids to form a purple colored compound called Ruhemann’s purple prints hours commonly sprayed on the surface using an aerosol can; prints begin to appear within an hour; weaker may take up to 48

Methods of Detecting Fingerprints Physical Developer: chemical mixture used for visualizing latent prints. – silver nitrate-based liquid reagent – shown to be very effective for developing latent fingerprints on porous articles that may have been wet at one time

Preservation of Developed Prints Once the latent print has been visualized, it must be permanently preserved for future comparison and possible use in court as evidence. – The first step is to photograph – any camera equipped with a close-up lens will do • Photographs must be taken to provide an overall view of the print’s location with respect to other evidential items at the crime scene – One of two procedures is to follow photographs. • If object is small enough to be transported, the print should be covered in cellophane, and preserved in its entirety • If object is immoveable, if must be “lifted. ”

Transporting Prints • If the object is small enough to be transported without destroying the print, it should be preserved in its entirety. • Prints on large immovable objects that have been developed with a powder can best be preserved by “lifting” with a broad adhesive tape. • Then, the tape is placed on a properly labeled card that provides a good background contrast with the powder.

Brush it with aluminum powder The marks became visible Put a black rubber lifter on it Lifting Prints The marks are on the lifter Put a plastic sheet over it

Humorous Print

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