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Fingerprinting

Fingerprinting. The study of fingerprints is called dactylography . Points are plotted to on a grid, like a graph, which makes it easier to compare prints.

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Fingerprinting

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  1. Fingerprinting

  2. The study of fingerprints is called dactylography. • Points are plotted to on a grid, like a graph, which makes it easier to compare prints. • The Australian National Automated Fingerprint Identification System uses this system and has over two million sets of fingerprints on its database.

  3. Why use fingerprinting? • No two people have the same patterns—not even identical twins! • Your fingerprints are formed while you are in the womb, between the fourth and fifth months of gestation. • The ridges in your fingerprints give you the ability to grip objects. • The police have the right to take the fingerprints of suspects in criminal investigations.

  4. Fingerprints at Crime Scenes • Fingerprints identified at crime scenes fall into three categories: • Patent • Latent • Impressed • If the fingerprints of a suspect match at sixteen points or more with prints from a crime scene, then they may be used as evidence in a court of law. • Palm prints are also highly important in the compiling of evidence.

  5. Patent Fingerprints • Patent fingerprints are those that are clearly visible to the naked eye. • Normally made because the individual has had their fingers in some sort of liquid or powder. Mostly this would be blood, ink or oil. • The fingerprint is clearly visible and a close up photograph is often all that is necessary to record it.

  6. Latent Fingerprints • Latent fingerprints are prints that are not visible to the naked eye but are visible under certain conditions. • They can be made visible - or certainly more identifiable - by introducing them to a powder or chemical agent. • Ultra violet light is often used for the identification of fingerprints on surfaces where they would not normally be easily visible. • Latent prints can be collected by brushing over the prints with a magnesium powder and/or cyanocrylic chemical (the likes of which can be found in household superglue).

  7. Impressed fingerprints • Impressed prints are those that have been made in soft material or tissue by pressing down with the finger or hand. • These prints can be photographed or in certain circumstances moulds made if they are very fragile.

  8. How do we leave fingerprints? • Our skin is made of a layer of tough cells on the outside (epithelial tissue) with our own characteristic ridges on the fingers, hands, toes and feet. • Below the epithelial layer there are two types of gland. • The sweat glands release sweat, which contains water, salt and urea, onto the surface of the skin. • The sebaceous glands release oils onto the surface of the skin. • Every time we touch something we leave behind the water, oil, salt and urea. • When the police dust for prints, the chemical they dust with sticks to these fluids and so our fingerprints are exposed.

  9. Types of Fingerprints • Fingerprints are sorted into three main groups, arch, loop and whorl, with a fourth category called composite that is used if a fingerprint shows features of more than one of the three main types of print. • These categories were first described by Sir Edward Henry in 1898.

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