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Abstract
Summary & Conclusion The long story of that inescapable mark of identity has been told and retold for many years and in many ways. On the palm side of each person’s hands and on the soles of each person’s feet are prominent skin features that single him or her out from everyone else in the world. These fea¬tures are present in friction ridge skin which leaves behind impressions of its shapes when it comes into contact with an object. The impressions from the last finger joints are known as fingerprints. Using fingerprints to identify individual has become commonplace, and that identification role is an invaluable tool worldwide. What some people do not know is that the use of friction ridge skin impressions as a means of identification has been around for thousands of years and has been used in several cultures. Friction ridge skin impressions were used as proof of a person’s identity in China perhaps as early as 300 B.C.E., in Japan as early as 702 A.D. (Anno Domini), and in the United States since 1902. Study, research, and experimentation have led to and sup¬ported fingerprints as a means of individualization and a fo¬rensic tool of incalculable value. The research and practical knowledge accumulated over the course of many centuries will support the science. Embryology and Anatomy 1- Histological Structure of the Skin The skin is both the largest organ and the first line of protection in the human body, completely covering the body from head to toe; the skin is primarily consistent in nature everywhere except for the areas covering the palmar surfaces of the fingers and hands and the plantar surfaces of the toes and feet. The skin on these areas is referred to as friction ridge skin. 2- Friction Ridge Skin: Friction ridge skin refers to the skin of the palms of the hands and fingers as well as the soles of the feet and toes, it is known as friction ridge skin in the biometric and forensic communities due to the distinctive patterns of raised ridges that can be used in identification. a) Embryology: Friction ridges form in the uterus by the fourth month of fetal development and remain unchanged and absolute for a person’s lifetime, these unique factors make friction ridge skin ideal for use in personal identification. The epidermis is recognized as an overall fetal covering at a very early stage, at 3 weeks gestation, The first noticeable development of friction skin on the volar surfaces takes place at about six week gestation, By weeks 10 to 12 the digital pads have become distinct development continue and the primary dermal ridges continue to develop within the dermis until 15 to 16 weeks gestation. b) Anatomy: Friction ridges are three-dimensional structures with irregular surfaces, separated by narrower furrows or valleys. Skin generally consists of a three-layer structure: the epidermis, dermis and subcutaneous tissues. At the boundary between the epidermis and dermis are finger-like projecting structures that project into the overlying tissue. The portion of the epidermis that projects into the dermis is called the epidermal ridge, and the portion of the dermis that projects into the epidermis is called the dermal papilla. Examination of Friction Ridge Skin Fingerprint examination is one of the most popular biometric technologies and is used in personal identification, criminal investigations, computer network logon, electronic data security, and internet access. Principles of Friction Ridge Skin Examination: The use of friction ridge skin comparisons as a means of identification is based on the fact that the pattern of friction ridge skin is both unique and permanent. Different systems have been discussed friction ridge classification including: 1. Manual fingerprint recognition systems: The most commonly used procedure passes into four distinctive phases: Analysis, Comparison, Evaluation, and Verification. (a) Analysis: This initial step calls for an analysis of the recovered mark to assess: The reality of its ridge formations, and their clarity. The analysis is focused on the unknown mark in order to determine, in total objectivity without having access to a known print, what information is visible and reliable, taking into account the clarity of the image, the effects of pressure, distortion, media, and development techniques. Friction Ridge Skin Features: I- Flow of Friction Ridges Level 1 refers to the overall pattern formed by the flow of papillary ridges on the papillary surface of the fingertips. Traditionally, the general pattern formed on the fingertips has been classified into generic classes. These systems distinguished several pattern of papillary ridges: arches, loops, whorls and composite pattern. II- Ridge Counting and Tracing The ridge count is the number of ridges intervening between the delta and the core. It is usually determined by a line passes from delta to core. Ridges that touch or cross this line are used in ridge count. If a bifurcation of a ridge is crossed by this line it is counted as two ridges. Dots are counted as ridges but delta and cores are not counted. Ridge counting was used extensively in Henry classification. Level 2 refers to major ridge path deviations, also known as minutiae, points of identification, or Galton characteristics. Basic forms are ridge endings, bifurcations, and dots. Additional types of minutiae (combinations of the basic minutiae) have been identified as being more specific than their basic components. Occasional features such as warts, scars, creases, and wrinkles are also referred to as level 2 features, incipient or subsidiary ridges. Level 3 refers to intrinsic or innate ridge formations, the alignment and shape of each ridge unit sweat pore shape, and relative positions. The ridges are punctuated by a series of sweat pores. While on average the spacing of the pores is relatively regular, the specific locations of pores are distinctive features that are used in identification. (b) Comparison: Basically, the comparison process is a comparison between the unknown mark and a known print, focusing successively on level 1, level 2, and level 3 features, and taking into account the quality of the mark. As the clarity of the unknown mark is generally inferior to the quality of the known print, when both images are compared, our suggestive brain tends to compensate for any differences. (c) Evaluation: The examiner faces a set of observations from which an inference about the identity of source must be drawn. An exclusion decision logically follows when discrepancies are observed that cannot be explained other than by the hypothesis of different sources. Such discrepancies can be observed at any level of the comparison between the unknown mark and the known print (d) Verification: The highly subjective recognition process exploits the extraordinary power of the human eye–brain combination, and the ability of the examiner is crucial. But this is not to say that fingerprint identification is unreliable. Nevertheless, such subjective judgments should be monitored in a structured and disciplined environment. 2. Automated fingerprint identification systems (AFIS) Automated fingerprint identification systems (AFIS) represent the single biggest advance in fingerprint identification technology. It helps forensic expert to compare a fingerprint discovered at the crime scene with a criminal fingerprint database. An Automated Fingerprint Identification System have and continue to replace outdated manual methods of fingerprint identification as the amount of human effort to conduct a manual search for a discovered print against several million inked prints is impossible on the other hand the search of prints on file in an AFIS database only takes about 10 minutes, also allow cost savings, ability to search crime scene prints, and improve quality of prints. Medicolegal Application of Friction Ridge Examination Friction ridge examination is one of the oldest and most common types of investigation found at a crime scene. One of the primary goals of this investigation deals with identification. Nowadays, other medicolegal applications of friction ridge examination have been found such as identification of diseases, fingerprint forgery, toxicological application, gender classification, and identification of blood group. 1- Personal Identification: The basic method of recording friction ridge detail on the hands or feet can be accomplished by applying a thin coat of black ink directly to the skin’s surface using a roller or by coating an inking plate with the ink and rolling the fingers onto the plate. The difference in elevation between the ridges and the furrows of the friction ridge skin leaves a print that is a recording of the unique detail of the friction ridge skin, this is called ten-print card. 2-Identification of Diseases: Disease or damage to the friction skin due to accident or a particular occupational injury causes abnormal friction ridges which are considered acquired causes, while others are caused by prenatal conditions, called as developmental causes which are non acquired causes. A- Acquired Causes An injury (e.g. cut or burn) penetrating into the dermal layer through the dermal papillae, will result in the ridges not being regenerated. Scar tissue will form to the extent that the damage occurred, and those ridges in the path of the injury should be permanently affected. B- Chromosomal disorders During the foetal stage, if a disruption occurs while the proliferation of cells at the generating layer of the epidermis is taking place, a ridge abnormality known as ”dissociation” may occur. Genetic and environmental factors can influence their formation. One study of foetuses with chromosomal abnormalities showed that the dermatoglyphic patterns were delayed by more than two weeks; some developmental causes that may be associated with changes in friction ridges such as Down syndrome, autism, breast cancer and turner syndrome 3-Fingerprint Forgery: Fingerprint forgery is the planting of a fingerprint on a surface so that the fingerprint appears to have been left by the finger or fingers of the person to whom it can be identified in an attempt to mislead the police or another party, there are three methods of fingerprint forgery including the mold/ cast method, the photoengraving method and the direct transfer method. 4- Toxicological Application: When we touch surfaces or handle objects with our bare hands, we may leave behind not only a unique set of fingerprints, but also sweat. That sweat can contain telling clues about our habits after metabolizing drugs, these metabolites and other components of the drugs can appear in our sweat. If these drugs can be detected, detectives would have additional evidence at their disposal this method will add higher quality evidence analysis to crime scene investigations. 5- Gender Classification: Gender classification from fingerprints is an important step in forensic anthropology in order to identify the gender of a criminal and minimize the list of suspects search. The variation among females and males in the membership of the fingerprints to the different pattern types, and the average ridge count for fingers belonging to each pattern type, are very small, and thus are statistically insignificant. 6- Identification of Blood Group: That there is an association between distribution of finger print pattern and blood groups. The general distribution pattern of the primary finger print was of the same order in individuals with A, B, AB and O blood group. It was found that loops are common with blood group A and arches were more in blood group AB. Individuals of blood groups A, B and O had high frequency of loops in thumb and little finger whereas ring fingers had more whorls and index and middle fingers presented higher incidences of arches. Individuals of blood group AB had high frequency of whorl in thumb, index and ring fingers while middle and little fingers showed more number of loops. Handling of Fingerprints in the Crime Scene I- Retrieval of Fingerprints from Crime Scene There is an interaction between the friction ridge skin, the secretions, and the surface at the moment of deposition. When the fingers touch a solid surface, sweat is transferred, depending on a number of factors, including: Temperature of the surface, Surface structure, and Electrostatic forces on the print-receptive surface. Fingerprints can be divided into three main groups: plastic fingerprints, visible fingerprints and latent fingerprints Different conditions that can affect latent prints as the following: Type of surface: which may be porous surface, nonporous surfaces, semiporous surfaces, manner in which the object was touched, weather, humidity, perspiration and care of the suspect. II- Fingerprint Visualizing Techniques There are many advances in fingerprint visualizing techniques which have been occurred, most of these techniques involve chemical reagents that react with materials present in the components that make up the print or contaminants, Powder Techniques and Laser and alternative light sources. III- Fingerprints Preservation The permanent preservation of fingerprints, independent of their nature, is important for future comparison and use as potential evidence. It is divided into: 1- Preservation by photography 2- Preservation of plastic fingerprints and 3- Preservation with fingerprint-lifting tape.