Forgery: Forging a document is not an easy process. Usually the words are removed by erasing them with rubber or by scraping them off with a razor blade. This is a simple way to do them, but sometimes forgeries are done more expertly. Erasures by a rubber eraser are often not detected by the human eye. In such cases lycopodium powder is used to dust the document. Unfortunately this powder cannot detect the use of plastic erasers. Forged Signatures: A forged signature is a signature that is suspected to be written by someone else who it claims to be. In most cases of signature forgery, they are first tracedin pencil by a real signature, and then inked over with pen. This cannot be seen by the naked eye, and can only be recognized by analyzing it under a microscope. This can also be examined by an infra- red light, so pencil markings show up. However, some forged signatures are not forged, and rather done by free-hand. These are only done with pen, so the flow of the signature on the paper is much smoother. But, when forging a signature that is not your own, the forager will hesitate, and might even lift the pen off the paper. This tells examiners that the forager was hesitant, and it was lack the fluency of a true signature. | Lie Detectors: A polygraph known as a liedetector is a machine that ensures one person is telling the truth about past or recent behaviors. The polygraph records changes in heart beats, blood pressure, respiration and electrical resistant’s. The polygraph is used as a lie detector by police departments. The theory about polygraphs is that when people lie they also get nervous about lying. Their heartbeat increases, blood pressure goes up, breathing rhythm change and perspiration increases. The polygraph was invented in 1921 by John Larson and then followed by many others who improved this machine. 
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