Analyse
The first step, analysis, is an intelligence gathering process to ascertain and establish the amount of friction ridge detail present within the unknown mark and also consider the following factors:
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Substrate
The surface on which the unknown mark was discovered (glass, paper, polythene bag etc).
Matrix
- The substance that the unknown mark was made by. This may be sweat from the person who left the mark, blood, oil or any other foreign substance capable of leaving an impression.
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Development medium
- The method by which the scene of crime officer or laboratory technician recovered the unknown mark to make it visible for identification. These include fingerprint powders, ninhydrin (a chemical which reacts with sweat and is used on paper) or superglue which is used to recover marks on plastics. The development medium used may have an effect on the appearance of the ridges and the quality of the print.
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Distortion
- If there was any pressure placed on the unknown mark when it was deposited or movement as this can affect the appearance of the ridges.