Forensic Document Examination - Essay Example

Forensic Document Examination Questioned documents are a common case in many legal proceedings. Forensic analysts are thus faced with a task of analysis the contents of the documents, nature of the materials used and the source. One of the primary tasks of forensic experts is to examine the individual characteristics of a document and match them with characteristics of a printer or photocopier. The printers and copiers always transfer their characteristics to the documents. The paper discusses the various characteristics of printers and copiers that make them readily identifiable. Such characteristics include; toner elements, grabber marks, graphic marks from specific printers and indentations. Forensic Document Examination The modern world is experiencing more sophisticated criminal activities that use technology to hide the identity. One of the commonly used method in crime propagation is the use of typewritten documents. Printed documents are used for criminal purposes such as communication, threatening, or soliciting ransom. Investigators thus face a dilemma on how to track the suspects. However, locating the machine used in printing or photocopying the documents is critical in narrowing the search area. Several methods are used to identify the machine that printed a particular document. The machines are traced from the unique characteristics of their output. Some of the characteristics include; paper banding due to variations in speeds of toner cartridges, marks from feed system, graphic marks put by specific printers and identification of indentations using Electrostatic Detection Device (EDD). According to Chiang et al. (2004) printer prices have enormously dropped, and almost everyone can afford one. However, the manufacturers of these printing machines lower the quality of the machines to reduce costs of production. Changes are visible in aspects such as plastics gears that move the toner cartridge. The cartridge gears are also never uniform making toners cartridges run at different speeds. Every printer or photocopiers have unique toning pattern as a result of toner morphology and chemical composition (Girard, 2013). Forensic experts are thus able to determine the machine used in printing or photocopying a paper. As noted, the variability in cartridge speeds inhibits accuracy of the toner. The photoconductor is subsequently rotated at different speeds. The situation leads to uneven detection of text or image with certain parts being darker and others lighter. The phenomenon is called banding and is common in printers and photocopiers that use rotation beams. The exact machines can be located by extraction of measurements of machines and mathematical features. These elements are then used against the exhibit document to trace and recognize the band patterns, and subsequently relate it to a specific machine. Marks from the feed system are other ways to determine where a document was printed. Different machines leave unique features from their feed systems. The grabbers of a printer leave unique marks on the paper that forensic experts can use to trace the type of machine used. The grabber drags the paper into the machine and results in marks such as edge depressions and grabber marks. The suspect machine can be located by comparing the grabber marks with several printers to determine the model, and hence narrow the search. Machines may leave unique marks on the output paper due to actions of the grabber (Girard, 2013). Despite the fact that similar models may leave similar marks, grabbers may encounter mechanical defects as a result of wear and tear. As a result, the output may have marks that are specific to the machine, and that exhibit the current nature of the grabbers. By so doing, the real machine used to print or photocopy a document can be easily identified. Advanced printers and photocopiers mark output papers with yellow dots that are invisible to the naked eye. The modification in printers, especially in the US, was requested by the government to curb crime. Printers graphically insert small marks on each paper such that the output can be traced to the printer. The dots are configured to communicate the information about the printer, including the model and the manufacturer. The marks make it easier for forensic analysis to identify the specific printer, provided they have the exhibit document. Several electro photographic printers transmit the yellow dots to the paper. As explained, the yellow dots communicate information about the printer such as the serial number (Peterson & Shenoi, 2009). The serial of the printer can thus be used to trace the owner of the printer. The information contained in the dots is extracted by a complex mechanism and is commonly done by the manufacturer or the government. Upon retrieval of the serial number, checks are done through the purchase history of the printers to determine the actual owner of the machine. Personal information of the buyer, such as credit card information, can be used to trace the residence of the purchaser, thus finding the suspect machine. Electrostatic Detection Device is used in identifying the intrinsic characteristics of a document that can trace the copier. The method does not destroy the original specimen as opposed to chromatography. The method clearly identifies the indented impressions that are in the document and invisible to the eye. The indentations are identified and magnified by the use of toners and charges. The process acts on the principle that indented areas have few negative charges. The toner pulls towards the areas with fewer negative charges, thereby showing the impressions in the areas. Electrostatic detection apparatus (ESDA) is accurate in picking out marks on the grabber and or roller. The process identifies unique marks on the questioned document and the characteristics of the suspect machine such as marks on rollers, feeder belt and marks on the drum. The said marks may have indented impression on the questioned document. The detected properties are counterchecked with a current copy from the suspect copier to certainty. Despite the many characteristics of printers and copiers that make them traceable, there are exceptional incidences where tracing such a machine becomes extremely difficult. One of the problems arises when the questioned documents are too old or in a detriment state. Such a document cannot be ideal to trace the printer or the photocopiers. Moreover, burnt documents are not easily traced if not handled properly at the crime scene (Fish, Miller, Braswell & Wallace, 2013). The above discussions prove that forensic analysts can use questioned documents to trace the printer or the photocopier machines. Printers and photocopiers have specific characteristics that are transferred to the documents. Such characteristics include the toner information, grabber marks, graphic marks and indentations. Forensic analysis of the questioned documents in the light of the said characteristics reveals crucial information about the source of the document. Tracing back the printer is a breakthrough in legal proceedings involving questioned documents. Despite the few shortcomings such as damage to the document, forensic equipment such as the Electrostatic device Detection provide more accuracy and ability to trace the sources of a document. References Chiang, P. J., Mikkilineni, A. K., Arslan, O., Kumontoy, R. M., Chiu, G. T. C., Delp, E. J., & Allebach, J. P. (2005). Extrinsic Signature Embedding in Text Document Using Exposure Modulation for Information Hiding and Secure Printing in Electrophotography. Purdue University. Fish, J. T., Miller L.S., Braswell, M. C., Wallace Jr., E. (2013). Crime scene investigation. Abingdon, Oxon: Routledge. Girard, J. (2013). Criminalistics: Forensic science, crime, and terrorism. Sudbury, Mass: Jones & Bartlett Learning. Peterson, G., & Shenoi, S. (2009). Advances in Digital Forensics V: Fifth IFIP WG 11.9 International Conference on Digital Forensics, Orlando, Florida, USA, January 26-28, 2009, Revised Selected Papers. Berlin: Springer Science and Business Media. Read More