Fraud And Forgery 

A schoolboy computer whizzkid penetrates the military computers controlling the US  missile system and convinces experts there that a World War is about to start.
    Fortunately, it all takes place in a movie - War Games released in the USA in 1984 and in the UK in 1986. But such fantasies about 'hacking' - as this activity is called - have come close to the truth. In 1985, seven teenagers were found guilty of hacking their way into computer systems controlled by the Pentagon, the US Military High Command headquarters, in Washington.
    By the time the FBI (Federal Bureau of Investigation) caught up with them, the hackers had access to information that would allow them to alter the position of American weather satellites.
    Many computers protect their stored information by insisting that a password is typed into the machine before access is allowed. Commercial computer networks, such as British Telecom's Prestel, have elaborate protection devices. But even these have fallen before the determined hacker.
    While hackers are becoming a serious menace to commercial companies who keep all their records on computer, far more dangerous are employees who use their knowledge of the company's passwords and accounting methods to syphon off cash for themselves.
    Computer fraud is merely the more glamorous form of a criminal activity that has beeb around as long as clever and skilled people have been able to simulate anything valuable, from passports to paintings and perfumes.
 
Spotting the fake
The most basic weapon in detecting fraud in a document is a sharp eye. Usually an experienced forensic scientist will first look for obvious clues, and then seek the aid of instruments, starting with a lowpower microscope.
    Most paper is manufactured with a particular watermark - an almost invisible, transparent symbol which can be seen when the paper is held up to the light. The mark is made when the paper is manufactured. It can be imitated using a wooden stamp and olive oil. However, the false imprint has sharper edges than the orginal, and can be detected using a microscope.
    Another way of checking a suspected fraud, such as a faked signature, is by viewing it under ultraviolet light. If the original signature has been removed, the impression it left will show up under the light.
    For futher investigation, the object, or a small portion of it, is subjected to chemical analysis.

Gamma ray dating
To determine its true age, a sample of an object may be made radioactive. The rate and intensity of gamma rays it emits can then be used to accurately calculate the age.
    The disadvantage of this method is that it leaves the sample highly radioactive, and so it must be kept well shielded afterwards to avoid dangerous radiation from it.
    Ancient artefacts able to withstand great heat, such as pottery, can be distinguished from fake lookalikes by method known as thermoluminescene. When the clay is fired to about 600 Celcious, it emits energy in the form of light, which can then be measured to calculate the date of origin of the clay.

Printing money
Banknotes have always attracted the attention of counterfeiters, and modern technology is making it much easier to produce high-quality colour copies of printed material. However, the companies responsible for designing and printing banknotes have introduced various measures to make realistic copies difficult to produce and to make foegeries easy to detct.
    Modern banknotes bear intricate designs containing numerous fine lines, originally made in metal by a master engraver. Such fine detail is extremely difficult to copy, even using the reproduction equipment. Other security measures include the use of intaglio (sunken) printing to give the notes a characteristic 'feel', special threads incorporated in the paper, the use of watermarks, and the individual number of the notes. Some notes are printed with a fluorescent metallic int, the appearance of which is impossible to reproduce by normal copying techniques.
    Some of the most attractive forgeries have been made by painters accomplished enough to imitate a great master. Their motives are varied, from frustration to resentment againt the established art world. If their art does not give them away, their materials do. Paints, pigments and techniques have changed greatly over the years, and sophisticated chemical detection means it is now extremely difficult to cheat the forensic scientist.

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