Fingerprints

 History of Fingerprinting

There are records of fingerprints being taken many centuries ago; ancient Babylonians pressed the tips of their fingertips into clay to record business transactions. Also, the Chinese used ink-on-paper finger impressions for business and to help identify their children.

The Discovery

Fingerprints weren't used as a method for identifying criminals until the 19th century. Scottish doctor Henry Faulds was working in Japan when he discovered fingerprints left by artists on ancient pieces of clay. This finding inspired him to begin investigating fingerprints. In 1880, Faulds wrote to his cousin, a famed naturalist Charles Darwin, and asked for help with developing a fingerprint classification system. Darwin did not accept, but he sent the letter to his cousin, Sir Francis Galton.




Sir Francis Galton

 

Galton was a eugenicist; he collected measurements on people around the world to determine the passage of character traits from one generation to another. In 1892, he published a book called "Fingerprints," in which he sketched a fingerprint classification system -- the first in existence. The system was based on patterns of arches, loops and whorls.

The Bertillonage (or anthropometry) method, developed by Alphonse Bertillon was a method of measuring heads, feet and other distinguishing body parts. These enabled police in different locations to apprehend suspects based on specific physical characteristics. This system was later adopted by The British Indian police in the 1890s.

Sir Edward Henry, commissioner of the Metropolitan Police of London, soon became interested in using fingerprints to catch criminals. In 1896, he added to Galton's technique, in turn creating his own classification system based on the direction, flow, pattern and other characteristics of the friction ridges in fingerprints. Truthfully, being the closest examiner of fingerprints as they are examined today. Examiners would turn these characteristics into equations and classifications that could distinguish one person's print from another's. The Henry Classification System replaced the Bertillonage system as the primary method of fingerprint classification throughout most of the world.

In 1901, Scotland Yard established its first Fingerprint Bureau. The following year, fingerprints were presented as evidence for the first time in English courts. In 1903, the New York state prisons began to utilize fingerprints, and later by the FBI.

Types of Finger prints 

There are three types of prints in a crime scene; these include plastic prints, visible/direct prints, and true latent or invisible prints. Plastic prints are usually left on “soft surfaces” such as soap, dust or wax. Plastic prints are easy to find because they are usually visible to the eye. Visible/direct prints are prints that are left behind once the individuals hand have been in contact with “colored material” such as blood, ink, or grease. Latent prints are prints left behind by the oils or perspiration of the individual, therefore, making these prints difficult to locate. 

Plastic Print

Techniques and Chemicals used to identify prints

 There are various techniques that are used to visualize a print; some of these techniques are applied by using chemicals, and fingerprint powders. The usage of the techniques depends on the surface of the print. For hard, nonabsorbent surfaces such as glass, tile, wood, etc. it is more convenient to use powder. Using chemical techniques are more effective when working with porous surfaces such as clothing. One of the oldest chemical techniques for the visualization of prints is the use iodine fuming, which is based upon the fact that iodine has a property to sublime. Another chemical used is silver nitrate, which is applied to the print and then exposed to ultraviolet light. Super glue fuming is also utilized, which in turn creates a white- appearing latent print.

Basic shapes and patterns of fingerprints.

There are three main fingerprint patterns: arches, loops and whorls.

Arches

Found in about 5% of fingerprint patterns encountered. The ridges run from one side to the other of the pattern, making no backward turn. Ordinarily, there is no delta in an arch pattern but where there a delta, no re-curving ridge must intervene between the core and delta points. There are four types of arch patterns: plain arches, radial arches, ulnar arches and tented arches. Plain arches have an even flow of ridges from one side to the other of the pattern, there are no thrusts and the ridges enter on one side of the impression, and flow out the other with a rise or wave in the center. The ridges of radial arches slope towards the thumb, have one delta and no re-curving ridges. On ulnar arches, the ridges slope towards the little finger, have one delta and no re-curving ridges. Tented arches have an angle, an up thrust, or two of the three basic characteristics of the loop. They don’t have the same flow that plain arches do and have up thrusts in the ridges near the middle that arrange themselves to form tents.

    

Loops

Usually occur in about 60-70 % of fingerprint patterns encountered. One or more of the ridges enters on either side of the impression, re-curves, touches or crosses the line running from the delta to the core and terminates on or in the direction of the side where the ridge or ridges entered. Each loop pattern has is one delta and one core and has a ridge count. Radial loops are named after the radius, a bone in the forearm that joins the hand on the same side as the thumb. The flow of the pattern in radial loops runs in the direction of the radius (toward the thumb). Radial loops are not very common and most of the time radial loops will be found on the index fingers. Ulnar loops are named after the ulna, a bone in the forearm. The ulna is on the same side as the little finger and the flow of the pattern in a ulnar loop runs in the direction of the ulna (toward the little finger).

Whorls

 In a whorl, some of the ridges make a turn through at least one circuit. Any fingerprint pattern which contains 2 or more deltas will be a whorl pattern. There are four types of whorl patterns. Plain whorls consist of one or more ridges which make or tend to make a complete circuit with two deltas, between which an imaginary line is drawn and at least one re-curving ridge within the inner pattern area is cut or touched. Central pocket loop whorls consist of at least one re-curving ridge or an obstruction at right angles to the line of flow, with two deltas, between which when an imaginary line is drawn, no re-curving ridge within the pattern area is cut or touched. Central pocket loop whorl ridges make one complete circuit which may be spiral, oval, circular or any variant of a circle. Double loop whorls consist of two separate and distinct loop formations with two separate and distinct shoulders for each core, two deltas and one or more ridges which make, a complete circuit. Between the two at least one re-curving ridge within the inner pattern area is cut or touched when an imaginary line is drawn. Accidental whorls consist of two different types of patterns with the exception of the plain arch, have two or more deltas or a pattern which possess some of the requirements for two or more different types or a pattern which conforms to none of the definitions.

        

 Procedures for collecting and lifting prints.

Depending on the surface that the print is on, it is crucial to follow the right procedures to collect the prints. For example, the most common for is dusting, which utilizes powder to see the print and then lifting it. For chemical prints, the procedures vary depending on the chemical that is being used.

For example if the chemical is iodine, the procedure is as follows. The iodine crystals are heated and the suspect material is put into the cabinet with the iodine crystals. Once the crystals have heated and interacted with the material, it makes the print in the print visible. An image of the print would need to be recorded since the print will easily fade after the iodine fuming. The print could also be sprayed with 1% solution of starch water, and the print will last for several weeks or a couple months.