Dactyloscopy the study of fingerprints

Fingerprints are a reproduction of friction skin ridges found on the palm side of the fingers and thumbs. The skin ridges are shaped by the dermal papillae, a boundary of cells separating the epidermis from the dermis.

Baby At 12 Weeks Old                                                         Baby At 12 Weeks Old                                                         Baby At 12 Weeks Old                                                         When do ridges form? In the womb approximately 10.5 weeks estimated gestational age. It is thought that the movement of the fetus is what contributes to the unique ridge characteristics. At only 10 weeks your babies heart is almost completely developed. An opening at the atruim of the heart and the presence of a bypass valve divert much of the blood away from the lungs, Your baby's blood is oxygenated through the placenta and the bypass valve of his heart directs most of his blood away from the lungs (this is automatically reversed when your child is born). Your babies teeth are now forming in the gums. By now his vocal chords are complete. Your baby can now even suck his thumb! The brain is fully formed, and your child can feel pain. This animation represents the currently accepted theory that localized cellular proliferations grow together into what subsequently appear as ridges at the epidermal / dermal junction at approximately 10.5 weeks estimated gestational age. For more animations – check out: http://www.clpex.com/images/Animations/Fusion.htm

The skin ridges are also populated with sweat glands, in which perspiration is discharged and deposited on the skin surface. Once the finger touches a surface, perspiration, along with oils, may be transferred onto that surface, leaving an impression of the finger’s ridge pattern, or fingerprint.

History In the mid 1800’s, Sir William James Herschel, an Englishman in India, began the first known official use of fingerprints by requiring natives to sign documents with the imprint of their right hand.

History In 1880, Dr. Henry Fauld wrote a publication suggesting that ridge patterns could be important for identification of criminals. This was rejected by Scotland Yard in favor of the Bertillon system.

History In 1883, a French police expert, Alphonse Bertillon, created a method of identification called anthropometry. This method consisted of eleven measurements of the human anatomy, including height, reach, width of head, and the length of the left foot.

History In 1892, Sir Frances Galton published Finger Prints, which discusses the anatomy of fingerprints and suggests methods for recording them.

History In 1897, Sir Edward Richard Henry proposed another classification system based on Galton’s work to develop a five pattern print system. This system was adopted by Scotland Yard and is presently being used in most English-speaking countries.

Fundamental Principles First Principle: A Fingerprint is an Individual Characteristic; No two fingers have yet been found to possess identical ridge characteristics. The individuality of a fingerprint is not determined by its general shape or pattern but by a careful study of its ridge characteristics, also known as minutiae.

Fundamental Principles Ridge Characteristics (Minutiae) Ridge ending Short ridge Dot or fragment Bifurcation Double bifurcation Trifurcation Bridge Island Enclosure Spur

Fundamental Principles Recognizing these ridges, their numbers, and their approximate location on a print make that fingerprint specific for each individual. There are as many as 150 individual ridge characteristics. A match is assumed if 10 to 16 points of reference are found on the two comparative fingerprints.

Ridge Characteristics

Fundamental Principles Second Principle: A Fingerprint will remain unchanged during an individual’s lifetime.

Though efforts have been made to obscure one’s fingerprints, it would be totally impossible to obliterate all the ridge characteristics on the hand, and the presence of permanent scars only provides new characteristics of identification. John Dillinger, a notorious gangster, tried to destroy his own fingerprints by applying acid.

Fundamental Principles Third Principle: Fingerprints have general ridge patterns that permit them to be systematically classified. All fingerprints are divided into three classes on the basis of their general pattern: Loops, Whorls, and Arches. These three classes form the basis for all 10-finger classification systems.

What are the three ways to classify fingerprints?

Arches Arches are the least common of the three patterns. They consist of only 5% of the population.

Classification The original Henry system converted ridge patterns on all 10 fingers into a series of letters and numbers arranged in the form of a fraction. The FBI needed to expand Henry’s classification capacity by modifying and adding additional extensions due to the increasing number of prints on file. This modification is known as the FBI system.

Classification The Primary Classification is the first step in the FBI system. A print is made of each finger A number value is given to each print that is a whorl, starting with 16 for the first pair, 8 for the second, 4, 2 and a value of 1 for the last pair. A value of zero is given to prints with an arch or loop pattern. The values are placed in a fraction sequence, added by 1, and equal a fraction (percent) to obtain the primary classification.

Fingerprint Comparison Three types of fingerprint files in use: Manual System— An examiner thumbs through each fingerprint card on file and makes an identification with no predetermined minimum set of comparison points. The Semiautomated System— IBM punch cards are used and compared to similar cards, according to Henry’s system. Fully Automated (AFIS)— a computerized system that houses a large data base of fingerprints of previously arrested persons.

Automated Fingerprint Identification System (AFIS) uses automatic scanning devices that convert the image of a fingerprint into digital minutiae that contain data showing ridge endings and bifurcations. When the scan is complete, the computer produces a list of file prints with the closest correlation to the search print. The selected prints are examined by an expert; AFIS makes no final decision.

Methods of Detection Fingerprints found at crime scenes can be described in three categories: Plastic Print Impressions Patent Print Impressions (visible) Latent Print Impressions (invisible)

Methods of Detection A plastic impression is a print that is readily visible with the naked eye due to the print detail being an impression in usually a soft surface. The most common types of surfaces or substances encountered at a crime scene are window putty, dust, dirt or mud.

PLASTIC FINGERPRINT IMPRESSIONS

Methods of Detection A patent print impression is readily visible to the naked eye. It usually results by a finger touching a surface after it has been in contact with a colored material. The most common substances found at a crime scene are blood, paint, grease, and ink.

PATENT FINGERPRINT IMPRESSIONS

Latent Prints Latent print impressions are prints not readily visible to the naked eye. These impressions are caused by the transfer of body perspiration and oils to a particular surface. There are several techniques to make a latent print become visible, depending upon the type of surface, the manner in which the prints were left, and the quantity of material left behind.

Latent Fingerprint Impressions Latent prints are made visible by using techniques to allow chemicals to adhere or bond to the water, proteins, or oils left behind.

Methods of Detection Prints are generally found on two types of surfaces: Porous Non Porous Paper Plastics Money Computers Checks Coins Maps Glass Notes Metal Cardboard Mirror Cloth Tile Non-Porous Plastics Computers Coins Glass Metal Mirror Tile

Methods of Detection Powders Fuming Chemicals Lighting There are over 50 methods available to develop latent fingerprints based on the surface. Some of these include: Powders Fuming Chemicals Lighting

Powders Black and magnetic black powders (graphite) are dusted on to latent fingerprints usually on nonporous surfaces. There are many colors of powders and some that are fluorescent.

Iodine Reacts with oils and fats Used on porous and nonporous surfaces if nonmetallic. Print fades rapidly.

NINHYDRIN (reacts with proteins) Used on porous surfaces NINHYDRIN (reacts with proteins) Used on porous surfaces. Use after iodine but before silver nitrate.

SILVER NITRATE Reacts with salts SILVER NITRATE Reacts with salts. Useful on paper, cardboard, plastics and light colored woods.

Cyanoacrylate (Superglue) Polymerizes with water Cyanoacrylate (Superglue) Polymerizes with water. Used on nonporous surfaces such as plastic and Styrofoam. Prints can not be lifted but can be powdered and photographed.

STICKY SIDE TAPE DEVELOPER

Other Prints Ears—shape, length and width Voice—electronic pulses measured on a spectrograph Foot—size of foot and toes; friction ridges on the foot Shoes—can be compared and identified by type of shoe, brand, size, year of purchase, and wear pattern.

Other Prints Palm—friction ridges can be identified and may be used against suspects.

Other Prints Footprints are taken at birth as a means of identification of infants but are not always done accurately.

Other Prints Lips—display several common patterns Short vertical lines Short horizontal lines Crosshatching Branching grooves

Other Prints Teeth—bite marks are unique and can be used to identify suspects. These imprints were placed in gum and could be matched to crime scene evidence.

Other Prints The blood vessel patterns in the eye may be unique to individuals. They are used today for various security purposes.