 The documents section of the FBI laboratory examines and compares for purposes of identification various types of written or printed matter. These include typewriting, hand printing, and most frequently, handwriting. Handwriting identification is based upon the fact that each person develops individual peculiarities in his handwriting, resulting from hundreds of thousands of repeated movements of the arm and fingers. Once the adult has developed a handwriting system, he finds it difficult or impossible to make changes in these reflexive actions. The courts agree with the statement that you see written here, and will accept expert testimony on handwriting identification. Identification depends, however, on sufficient samples for detailed comparison. Then the expert document examiner can isolate such personal characteristics as beginning strokes, connecting strokes, letter formation, and relative heights of letters. When these and other characteristics recur with sufficient consistency and frequency, the expert examiner can make positive identification between a known and a questioned document. The documents section of the FBI laboratory maintains and uses the national fraudulent check file to aid local law enforcement agencies in bogus check cases. The file contains perhaps the world's largest collection of bogus checks and of signatures used by professional check passers. Trained technicians search the file for similarities with checks submitted for investigation by local law enforcement agencies. When a possible is found, it is brought to the expert examiner handling the case. If his examination confirms the signature similarities, he requests the case file on the known check passer which may provide further samples for comparison. The document examiner, a special agent of the FBI, has been selected for a scientific background and natural aptitude. He is given formal and on-the-job training to gain the experience which qualifies him as an expert. He applies this experience to the questioned signature. The case file on the check passer may contain a variety of handwriting samples. They may include signatures on fingerprint cards, driver's license, or other handwritten samples previously collected as evidence. There may also be samples written voluntarily by the subject during a past investigation using the same wording as the questioned material. These are best for comparison. Sometimes the so-called London letter is dictated to a consenting suspect. It is designed to reveal the maximum number of handwriting characteristics. The examiner, thanks to his skill and training, can transcribe the significant known and questioned letters to his worksheet with astonishing accuracy. Now he is ready to indicate similarities or differences in letter formation. He finds tiny recurring patterns of loops, lines, placement, spacing, script style, and many others, which even the professional forger cannot altogether eliminate. He indicates similarities in the known and questioned letters with an arrow. This analysis provides the basis for his finding and will support his report and possible court testimony. Many people believe that hand printing is more difficult to identify than handwriting. The extensive reference file of bank robbery notes, most of them hand printed, helps to disprove this. A questioned bank robbery note sent in by a local law enforcement agency can be compared with these known samples. The technician's quick look turns up a possible. The examiner compares the note from the bank robbery note file and that received after a recent bank holdup. There are enough obvious similarities to indicate further study. He copies onto his worksheet letters which appear to have significant characteristics. This keeps the evidence free from undue handling or marking. He marks those from the file known and those from the evidence questioned. As in handwriting examinations, he looks for matching and recurring characteristics, letter formation, placement on the line, spacing, direction of stroke, and others. Although block printing has fewer signposts than handwriting, those that it has are obvious to the expert document examiner. And bank robbery notes, unlike check signatures, usually provide an adequate sample for comparison. Each similarity is ticked off with a straight arrow. Dissimilarities would be marked by an arrow footed by a perpendicular line. And a doubtful comparison would be pointed out by arrows footed with a circle. Document examination can yield other information. Heavy-handed block printing, so often found on bank robbery notes, can leave an indent of the undersheet of the pad. In this case, the police were thorough in their search of the suspect's room and meticulous in the preservation of evidence found there. The examiner will have a specially-lighted photograph made to back up his report on the content of the indentations. The examiner must be trained in other skills than the comparison evaluation of written instruments. He must be able to identify and date inks and papers using the standards of the FBI laboratory or the instrumental and chemical analytic equipment also available there. The notepad yields yet more evidence. The examiner confirms that the torn edge of the bank robbery note matches the torn edge remaining on the carefully preserved notepad. This too will be photographed and included in the examiner's report. Thus, his final report to the requesting law enforcement agency reflects his skill and experience in comparing hand printing, plus his knowledge and use of many other laboratory facilities and techniques. And he is available to testify as an expert witness at no cost to the requesting agency. This commercial office is visited by a police detective. He is there to look for evidence to be used in another important function of document work. Typewriter examination. To try and identify the writer of an extortion note, the detective uses a typewriter which has been readily available to one of the suspects in the case. He copies the extortion note exactly. To give the FBI document examiner the maximum opportunity for detailed comparisons. After dating and initialing the sample, he will send it to the FBI laboratory along with the extortion note itself. Both the known and questioned extortion note have been received at the document section of the FBI laboratory. The examiner's first step is to refer to the typewriter standards file to confirm make, model, and style of type for both notes. The comprehensive typewriter standards file often contains additional information. The date when a given type style was first introduced. Both current and obsolete models using this style with dates. And any modification which will affect the appearance of the typing along with dates. It is easily seen that every typewriter develops its own characteristics through use and abuse. After he has noted all the pertinent data from the typewriter standards file, the examiner starts his comparison of the actual extortion note. Marked, questioned, and the copy typed by the detective on the typewriter available to the suspect marked known. Using a magnifier, these are some of the things the document examiner looks for as he compares the two notes. The T of the questioned note repeatedly prints above the line. This is not so in the known copy and he marks it dissimilar. One eye also strikes above the line. But this may be due to shift key in motion. The upper left hand serif of one U is broken. On the other note, this character shows no damage. He marks the dissimilarity. He continues his comparison letter by question letter. The dissimilarities mount up. When the job is done, it is quite evident that the questioned extortion note was not typed on the machine available to the suspect. Reports sent to the requesting agency by the FBI laboratory examiners may indicate innocence as well as guilt. In many cases, the examiner testifies in court as an expert witness. His services are available to the law enforcement agency without charge. Examiners bring with them whatever can be used to support and explain their findings to a jury. The fraudulent check identification which this examiner made is admissible evidence in court. Document examination used to convict the guilty or to clear the innocent is a powerful weapon in the war against crime.