How Crime is Detected and Prevented
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How Crime is Detected and Prevented In this essay I will describe and explain how different methods are used to detect and prevent crimes. The different types are Alcohol, Arson, Ballistics, Blood, Documents, Drugs, Explosives, Fibres, Fingerprints, Footprints, Glass, Hair, Paint, Plastic, Pollen, Soil and finally Teeth. ALCOHOL: When a person is suspected of being under the influence of alcohol, the police can test them with different types of machines. These machines are called breathalysers. The Lion Alcolmeter S-L12 is the most common of these. These machines test the breath for traces of alcohol. If the suspect tests positive, they will be detained until they are cleared. Other ways of detecting alcohol on a person are physical tests. The police will ask the suspect to perform certain actions such as walking in a straight line and following a finger with there eyes. ARSON: When the forensic gets to the scene he must be very careful. An arson attack would burn away most of the evidence so the forensic must be careful where he treads. They would look under furniture and cloth, as this would have protected any fingerprints or fibres lying there. One of the most important roles of the forensic scientist following an arson attack is to establish the chemical nature of the accelerant - the material used to start the fire. When the evidence has been collected, it is tested with acetone (propanone), which dissolves most accelerants. They can then be tested with chromatography to finds out what they are. If the compounds break down when being tested, infrared spectroscopy is used instead. This test however is not 100% fool proof. It can be incorrect. BALLISTICS: This is the study of firearms and bullets. When a modern gun is fired, the spiral on the barrel leave's an imprint on the bullet. This can then be traced back to the make of the gun and even the gun itself.
This is a particularly useful method for all kinds of surfaces, including books and wallpaper, and is designed to develop prints that may be very old (30 years plus). Ninhydrin reacts with amino acids from sweat and produces various shades of blue-purple when developed. · Silver nitrate. This picks up salt in sweat. This can be sprayed onto a surface, such as wood or cardboard, or it can be applied with a brush or swab. It is allowed to dry for about five or ten minutes, then exposed to ultraviolet light (or sunlight). Prints developed this way also disappear after a short time, so have your camera ready. · Superglue fuming. Superglue vapour reacts with water in the print. A few drops of superglue are placed on a hotplate in a glass tank. The object is then placed in to the tank, and in about fifteen or twenty minutes, any prints that were invisible are now visible in greyish tone on the object. Fingerprint matching was traditionally done manually, but this has been revolutionised by computer technology. The FBI-NCIC classification system and other techniques known as the Henry Fraction assigns numerical values to overall patterns on an entire set of ten prints. This allows the coding and filing of tens of millions of prints in an orderly manner. TYRE PRINTS: When someone walks or runs, or drives a vehicle, over soil, impressions are left in the ground. A frame is built around the print or track, a suitable casting material is poured in and allowed to dry, and then the cast removed and photographed. As shoes and tyres are used, individual characteristics such as nicks, cuts, and wear patterns develop. These characteristics may show up in prints and impressions and can be compared with a suspect's shoes or tyres. Through the skilful combination of tracking and footwear impressions, it is often possible to recreate the events leading up to, those occurring during, and those occurring after the crime.
TEETH: If the body of a victim is found a long while after the crime was committed, it is likely that it will be impossible to identify the body. This is common after an arson attack. The only part of the body that can survive this is the teeth. People have different patterns of teeth. Some people have bigger jaws and so on. There are around 200 ways of charting teeth. The "Universal system" assigns a number to each tooth - starting with the upper right (third) molar - 1 - and finishing with the lower right (third) molar - 32. Information is also recorded about the five visible surfaces of each tooth, so a detailed dental record, or odontogram, is built up. Conventional forensic methods are used to collect teeth from the scene of the crime, or charred or exhumed remains. Visual examination and photography are used to examine/record teeth marks at the scene of the crime. For successful identification of remains, post Morton and ante Morton records must be available. Odontograms can be compared with teeth marks from the scene of crime. Teeth are also useful for determining a person's age - dental growth is 4 micrometer's per day and this growth is indicated by striations on the tooth. Because of this, it is possible to estimate the age of young people ± 20 days. After 25, identification becomes more difficult - teeth wear, the gums recede, the pulp cavities become smaller, etc, so the forensic odontologist can only give an approximate age - 42 months, at best. Crime prevention: There are many methods of preventing crime. Some are more efficient than others are. Things such as Vandal paint and CCTV are more of deterrents that do not actually stop the crime. They will help to catch the criminal afterwards. Other methods include Alarms, Security guards/ dogs, warning signs, fines, police and prison. There are many more ways of attempting to prevent crime. It is impossible to completely stop crime, as even with these Crime prevention techniques, people will still try to get away with criminal offences. ^
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