Fingerprint Techniques Essay, Research Paper
Fingerprint identification has been around for a long time. Dating back to 1856, Sir William Hershel began using fingerprints by requiring people to not only sign business contracts but to impress their hand on the back of the contract. In the beginning, his intentions were not directed at personal identification. The print was simply used to frighten him out of all thought of repudiating him signature (The History of Fingerprints). As Hershel s fingerprint collection grew, he began to note that the linked impressions could prove or disprove identity. During the 1870 s, Dr. Henry Faulds, a British Surgeon of Tsukiji Hospital in Japan, studied skin furrows after taking notice of finger marks on prehistoric pottery. He then devised a method of classification. Mr. Faulds passed on an explanation of his classification system, along with samples of the forms he had design for recording inked impressions, to Charles Darwin. However, because of Mr. Darwin s old age and ill health, he informed Faulds that he would pass the material on to his cousin Francis Galton. Sir Francis Galton, a British anthropologist, published a book called Fingerprints. The book included the first classification system for fingerprints can be identified. Galton identified the characteristics by which fingerprints can be identified. These same characteristics are in use today and are often referred to as Galton s Details. In 1892, Argentine Police Officer, Juan Vucetich, made the first criminal fingerprint identification. He was able to identify a woman who murdered her two sons because he found a bloody fingerprint that was left on the door and was able to match the print to the woman. In 1901, fingerprints for criminal investigation were introduced in England and Wales using both Francis
Galton s and Sir Richard Henry s observations. This began the Henry Classification System, which is still used today in all English speaking countries. In 1903, New York State Prison system began the first systematic use of fingerprints in the United States. 1905 was the year when the United States Army saw the use of fingerprints and within three years, the United States Navy and the Marine Corp. soon followed. As time went on, more and more law enforcement agencies joined in the use of fingerprints for personal identification. Many of these agencies began sending copies of their fingerprint cards to the National Bureau of Criminal Investigation. In 1924, Congress established the Identification Division of the FBI and by 1946, the FBI had processed 100 million fingerprint cards in manually maintained files. By 1971, that 100 million had increased to 200 million. With the introduction of the AFIS system, a computer system that has the ability to scan a print and convert it into a computerized image, the flies were split into computerized criminal files and manually maintained civil files. In 1999, the FBI planned to eliminate the use of paper fingerprint cards aiming to process all the files using the AFIS system. The new Integrated AFIS system now holds approximately 33 million computerized fingerprint records (The History of Fingerprints).
Fingerprints possess certain factors that make them the most positive form of personal identification known. The first being individuality. No two fingerprints are alike. Also, the ridge arrangement on each finger of every individual is different. Another factor is that fingerprints are permanent. Prints are formed prior to birth and remain the same until decomposition. The last factor is immutability. Fingerprints do not wear out and they are very hard to destroy. An exception to this may occur if a finger is severely burned or cut.
The pattern area of a fingerprint is the only part of the fingerprint impression used in classification. Patterns areas are enclosed by type lines, the two innermost ridges that start parallel, diverge and surround the pattern area. The delta is the point on a ridge that is nearest to the center of the divergence of the type lines. The core is the approximate center of the finger impression.
Fingerprint patterns are divided into three general groups and eight subgroups. The most common is the loop, making up 65% of the impressions. The loop has one or more ridges that enter on either side of the impression. They re-curve, touch or pass through an imaginary line drawn from the delta to the core and terminate on or toward the same side of the impression from where they entered or originated. A loop has one or more ridges and must have one delta. There are two types of loops. The first being radial loops. The radial loop ridges flow in the same direction of the thumb, the radius bone. Ulnar loops ridges flow in the direction of the little finger, the ulna bone. The next type of pattern is the Arch. The arch had no type lines or deltas and makes up for 5% of the impressions. There are also two types of arches. One is the plain arch, which the ridges enter form one side of the impression and flow out the other side with a rise or wave in the center. A tented arch has the same description however, there is a ridge at the center that does not flow out the other side. Those ridges form a definite upthrust or angle of 90% or less from the horizontal plane. The last type of pattern is the whorl. Whorls make up 30% of the impressions and must have two deltas. There are four types of whorls. The first is the plain whorl, which is the most common. It has two deltas and at least one ridge making a complete circuit that can be spiral, oval, circular, or any variant of a circle. The imaginary line drawn between the two deltas must touch or cross at least one of the re-curving lives. The next is the central pocket loop whorl. This has two deltas and at least one ridge making a complete circuit. However, the imaginary line between the two deltas must not touch or cross any of the re-curving lines. Another type of whorl is the double loop whorl. This consists of two separate loop formations with two separate and distinct sets of shoulders and two deltas. The last type of whorl is the accidental whorl. This is a pattern consisting of a combination of patterns of two different types of patterns, except for the plain arch, with two or more deltas. The combination may include a loop and tented arch or double loop and central pocket loop. Also, underneath every pattern there are ridges running from one side to the other.
When classifying fingerprints, a specific pattern must be followed. All ten blocks on the fingerprint card are assigned a numerical value. Fingers 1 and 2 are assigned a value of 16 points. 3 and 4 are assigned 8 points. 5 and 6 are assigned 6 points. 7 and 8 are assigned 2 points. 9 and 10 are assigned 1 point. The only type of fingerprint that is classified is the whorl. If there is a whorl in block 1 or 2, then it receives a value of 16 points and so on. The primary fingerprint classification will be shown (or expressed) as a fraction (that is not reduced) and the numbers are obtained by placing the even numbered finger over the odd numbered finger. After finding the value of each finger, both the numerator and the denominator get 1 added to the sum. Common errors in computing primary fingerprint classifications are computing the right hand over the left hand instead of even numbers over odd numbers. Another common error is forgetting to add the 1 at the end to the numerator and denominator. The maximum or highest primary fingerprint classification that can be obtained is 32/32, which means all the fingers have whorls. The lowest primary fingerprint classification that can be obtained is 1/1, which means no fingers have whorls. When classifying amputations, certain consideration needs to be taken. When one finger is amputated or missing it is given the classification identical with that of the opposite finger including the pattern and ridge count or tracing and it is reference to every other possible classification. With two or more amputations, the same procedure is made.
When taking rolled impressions, all 10 must be completely rolled from side to side to obtain all available ridge detail. The bottom of the fingerprint card is for plain of fixed prints, not rolled. They must be taken simultaneously to obtain accuracy of prints. Generally, when rolling impressions the fingers must be clean. They must be rolled completely with as little ink as possible. The fingers must be relaxed and the person should not help the operator. The entire block on the card should be filled out with the print and ridge detail. The right hand first, then the left hand, followed by the fixed impressions.
The card must be filled out completely including signatures, before printing. The are primary reasons for the rejection of the fingerprints cards by the FBI. The first is that the delta and the core of loops are not clear. Also, intervening ridges are not clear which enables the examiner to do a ridge count. Another reason is that the deltas are not present or clear in whorls. Also the ridges running between deltas are not clear enough to do a trading. A ridge count is the number of ridges intervening between the delta and the core. Tracing depends upon the establishment of focal points on the deltas. Ridges emanating from the lower side or point of the extreme left delta are traced until the point nearest or opposite the right delta is reached. If the ridge traced passes inside the right delta, the inner tracing is noted. Three or more outside the delta results in an outer tracing. All others are called meeting tracings.
When comparing an unknown latent impression with an inked impression of known origin to determine whether both were made by the same finger an ident expert looks for four different elements. The first is the likeness of the general pattern type or if the type can not be determined because the questioned pattern is incomplete. The second is the qualitative likeness of the ridge characteristics. The third is the quantitative likeness of the ridge characteristics. The last is the likeness of the location of the characteristics. Most latent impressions developed at the crime scene are badly blurred, smudged or consist of artificially superimposed impressions of different fingers. As long as a sufficiently large area is available, an ident can be made. The size of the area required varies according to the number of individual ridge characteristics discovered and the frequency of their appearance in given area. Based upon all available data, no valid basis exists at this time for requiring that a pre-determined minimum number of friction ridge characteristics must be present in two impressions in order to establish positive identification. Although this might be interpreted as a negative position .. and certainly a position contradictory to the conventional attitude taken in some political entitles that a minimum of at least 10 to 12 matching characteristics must be clearly definable before identification can be established (Standardization Committee IAI, Identification News). This refers to the quantitative likeness. The qualitative likeness refers to whether or not the characteristics are the same in both prints. The likeness of location refers to the relationship to one another within the contours of the pattern. In comparing questioned and known prints, some dissimilarities may be found. If they are explainable, such as distortion, partial blurring, filling up of ridges with the developing powder, they have no effect on establishing a positive identification. If there is an unexplained dissimilarity, appearance of defined ridge characteristic in one print but not the other, then no ident can be made.
The simplest and most common procedure for latent print development is powder dusting. The application is by brushing instantly apparent prints. Black ferric oxide is the most commonly used powder used when dusting for prints, along with a camel hair brush. A visual search of the surface must be done first before lifting the prints. The prints should then be photographed. Next, carefully apply the powder with light action. Too much powder and too little brushing are common errors. Brush marks may destroy details. The excess powder should be removed by dusting the surface with gentle, smooth motion. Lift the print with tape and place on a background. Another form of processing is chemical fuming. The first is iodine fuming. The iodine bonds with unsaturated fatty acids in fingerprint residue. Iodine crystals are heated and a violet iodine vapor is produced. The vapor turns the prints to a yellowish color. The fumes are toxic and the prints fade quickly. This process will not develop older prints. The next procedure is cyonoacrylate fuming, super glue. Diversity of use is one of its advantages especially on items not previously thought to be viable for fingerprint development. Numerous procedures and modifications exist with this chemical. They are fuming procedure, fume circulation, heat acceleration procedure, and the chemical acceleration procedure. Basically all processes are designed to accomplish acceleration of polymerization process and to prolong volatilization. Another chemical alternative is Ninhydrine. This is very good at developing old prints. It is based on its reaction with amino acids. It is applied by swabbing, spraying or dipping. The reaction is accelerated by the application of a heat source such as ovens, irons, stream, or hair dryers. The surface is sprayed and the solvent, acetone methanol, has to evaporate (dry). A heat source is then applied and the specimen is let at room temperature until the prints develop. The sliver nitrate reagent has been used for over 100 years. The basic principle is the reaction with sodium chloride. The product of this reaction is silver chloride. An ultra violet light is used to accelerate the reaction and development. The detection of fingerprints on the skin has two methods considering the apparent problems. The first is the iodine-fuming gun. This process is done by heating iodine crystals in the gun and directing fumed onto the skin. A silver sheet is developed on the skin and the exposure of the plate to strong light develops the print. This process could take up to several days. The next process is the cyanoacrylate fuming and dusting process. The body or specific body area must be covered with a tank or box like device. The super glue is heated and a small fan is used to distribute the fumes around once the glue begins to fume. The time period can be 5 seconds to 2 minutes considering the area is small. If using powder, the powder may be regular black magnetic powder. The prints should again be photographed and then lifted with tape directly form the body. Bodies should not be processed after being refrigerated. Condensation build up tends to wash away prints or distort prints. Laser technology is a fairly new form used to develop prints. It was developed in 1954 and was first used in 1976 for the development of fingerprints at a crime scene by visualization of their inherent fluorescence when excited by a laser. Laser is an acronym for light amplification by stimulated emission of radiation (forensic light). Th light source is a bright light source of high intensity, usually green-blue or green-red. There are several types of light sources used in this process. One is the pulsed or strobe. Another is the continuous wave, a steady beam. Also, a portable or non-portable. Finally, a turnable or adjustable wave length is used.
One of the processes is called the inherent latent print luminescence. There area approximately 20 elements found in sweat. Riboflavin and pyridoxine interact with sodium graps and become the primary elements of inherent luminescence. The majority of the prints do not exhibit sufficiently strong inherent luminescence however, this changes with changes in temperature and nervous state.
When DNA is subjected to restriction-enzyme activity, fragments of various sizes are formed. Each human family line has its own unique pattern of restriction-enzyme DNA fragments. This variation in patterns of DNA fragments found in human genetic lineages is called “restriction-fragment length polymorphism” (RFLP). Because each person, except for identical twins, is formed from different combinations of the genetic material from two family lines, the pattern of sizes of the fragments from an individual is unique and can serve as a “DNA fingerprint” of that person. This fact has been crucial in identifying assailants in a number of violent crimes where the victims were unable to do so. In these cases, bloodstains or semen stains on clothing, sperm cells found in a vaginal swab taken after a rape, or root hairs of the assailant were available for analysis. Extraction of DNA from dried blood or from one of the other sources, followed by enzymatic digestion, results in an unambiguous match of DNA fragments with DNA obtained from cells of the accused. Where bloodstains are available, clear-cut DNA fingerprints are obtainable from samples that are as much as four years old.
The Federal Bureau of Investigation’s (FBI’s) Integrated Automated Fingerprint Identification System (IAFIS) is being developed to sustain the FBI’s mission to provide identification services to the nation’s law enforcement community and to organizations where criminal background histories are a critical factor in consideration for employment. The IAFIS will serve the FBI well into the twenty-first century and represents a quantum leap in communications, computing, and data storage and retrieval technologies.
The IAFIS will provide ten-print, latent print, subject search, and criminal history request services, document submission, and image request services to FBI Service Providers, and federal, state, and local law enforcement users. IAFIS is being procured as three segments: the Automated Fingerprint Identification System (AFIS) segment, the Interstate Identification Index (III) segment, and the Identification, Tasking, and Networking (ITN). Each segment provides discrete capabilities and works in conjunction with the other segments to support FBI Service Providers and external users in their law enforcement capacities.
In earlier civilizations, branding and even maiming were used to mark the criminal for what he was. The thief was deprived of the hand which committed the thievery. The Romans employed the tattoo needle to identify and prevent desertion of mercenary soldiers. More recently, law enforcement officers with extraordinary visual memories, so called camera eyes identified old offenders by sight. Photography lessened the burden on memory but was not the answer to the criminal identification problem; personal appearances change. Fingerprints offer an infallible means of personal identification. That is the essential explanation for their having supplanted other methods of establishing the identities of criminals reluctant to admit previous arrests. Other personal characteristics change- fingerprints do not.