FORENSIC DOCUMENT EXAMINATION
The functions of document examiners may be summarized as involving conduction of scientific examinations, making comparisons, and document analysis with the aim of
Identifying eliminating a person as the source of handwriting.
Identificationelimination of typewriting sources as well as other impressions.
Writing of reports or issuing of testimonies to understand examiners findings.
Establishing the genuineness of a document hence exposing forgery, alterations, additions or deletions.
Documents are generally part and parcel of life. They are used in business as well as personal life. Basically any document may be subject to forensic examination once its under dispute either in an investigation or in litigation. These documents may include simple sheets of paper bearing a persons handwriting, forged cheques, business contracts or even ransom notes (Osborn, 192911). In general any document that bears marks, signs, or any symbols intended to convey some kind of message may be subject to an examination.
The aims of document examination include
Handwriting and signatures identification.
Forgery document identification.
Typewriters, check writers, and photocopies identification.
Detection of alterations, additions, deletions, or substitutions
Deciphering and identification of indented writing
Inks comparison and identification of writing instrument types.
In general it looks at indentations, paper type, size, color, thickness, Water marks, Ink pencil, unique marks of photocopiers, physical matching, and handwriting.
Indentation
Indentations refer to imprints that are left on the underlying pages when the sheets are written upon. These writing impressions may be influenced by pen pressures as well as paper thickness. Usually ESDA machines are used to identify them (Ellen, 200518).
Paper type, size, color, thickness
This involves comparison of the materials used in the disputed document to materials of other standard document that is considered valid. This includes examining if their type, size, color and thickness match each other.
Water marks
These are recognizable images or patterns which appear in papers as various shades of lightnessdarkness upon being viewed by the use of transmitted light. They can also be viewed using reflected light on top of a dark background.
Ink pencils
Inks and pencils refer to materials that are used to put writings on a document. Through comparison of ink used on one document to that used in another, it is possible to identify if the documents bares similar origin hence establishing its validity. Comparison of inks may be done through use of chemical and optical device techniques.
Photocopier unique marks
Examination of photocopied, inkjet and laser printed documents can be used to establish links and relation of a document under dispute to another document that is considered standard. By identifying the photocopier or printer that was used to print a document, it is possible to determine whether the document originated from a valid source or not.
Physical matching
This method applies the use of document matching apparatus in comparison of structural operations. Recent technology is based on the visual structure of the document. A documents structural information is generated and compared to similar standard document structural component. Image point sets are generated and compared corresponding image point sets from the standard documents to establish whether they match within predetermined tolerances(Ellen, 200512).. Through these examinations, it is possible to identify and decipher alterations, erasures and any obliteration that may be present in a document (Ellen, 200526). Mostly document examiners are able to reconstruct documents that are either damaged or shredded.
Handwriting and signatures examination
This involves comparison of signatures and handwriting to known specimens with the aim of establishing authorship as well as to detect simulations.
Handwriting examination basically involves three steps namely
Analysis at this point the known specimens are broken down into pieces that bear perceptible characteristics.
Comparison the characteristics of the document in question are then compared to those from the already known specimen.
Evaluation obtained similarities and differences are evaluated to establish the ones that are helpful in drawing conclusions. Usually this is determined based on the appearance frequency of the given item.
Upon competition of the aforementioned steps, verificationvalidation may take place after which conclusions are drawn.
Documents to be examined require proper handling and storage in order to minimize deviations of expected results. Evidence handling therefore is a fundamental process that ends up determining the level of success of document examination process. Evidence handling involves preservation as well as storage, handling of wet documents as well as original document handling.
EVIDENCE HANDLING
Once evidence material has been identified, the important step of collecting them and preserving them comes in to play. It is important that the officer collecting the evidence do not touch the evidence using bare hand. It is necessary that the officer wears latex gloves to move the evidence from its place of finding to the desired location. Usually, it is recommended that the items be placed in a plastic bag or envelope. Those items that cannot be stored in the aforementioned containers should be stored appropriately and consequently labeled.
The containers should bear labels clearly indicating the following
The nature of contents it bears.
Location of finding of the evidence.
Name of the people in the area at the time.
Name of persons witnessing the finding of the evidence.
Date and the time when the evidence was found.
There is always need to identify objects that might contaminate each in order to separately store them. However, it will be important to note that different types of evidence require varying handling procedures.
The officer handling the evidence must sign after handing over the evidence for storage and approve that the contents are as marked on a given specific date. The receiving officer must similarly hold the same record clearly signed by both him and the handing over officer
Evidence storage may be temporary or permanent. Once evidence is collected, its important that they are stored in a way that minimizes the risk of contamination. The method used for storage differs from one kind of evidence to another. Special focus is put on wet evidence. Its important to note that this kind of evidence contain moisture which allows for growth of microorganisms which might prove destructive or even alter evidence. Such kind of evidence should therefore not be packaged in plastic bagscontainers. In cases where such evidence has been collected in plastic containers temporarily, they should be immediately removed and left to dry once in a secure location.
All evidence must be stored in a secure and restricted area to avoid it being tampered with mostly secure cabinets or evidence safes are used. This allows for the evidence to be presented in a court examination while in a good condition through limiting third party interference.
Original documents should be handled carefully in order to avoid destructive effects on them. They should be stored in places that are free from chemicals and liquids that might be destructive to them. In comparing of these original documents to documents in question, its important that the original document is kept form damage or harm that may come its way. Its important that after the process, the document maintains its original form.
TECHNIQUES USED IN DOCUMENT EXAMINATION
There are various techniques applied in document examination depending on the kind of examination taking place at that given time
IR and UV photography
Despite the human eye being a remarkable imaging instrument, its chromatic sensitivity is limited to the visible spectrum which ranges from wavelengths of 400 nanometers to 700 nanometers (Ellen, 200532). Realm of ordinary digital and film photography also fall within this range. There are some instances therefore when ordinary visible light is unable to reveal the fine details of a document. It is in such instances when forensic scientists employ the use of UV an IR light.
The wavelengths that fall under 400 nanometers are denied by scientists as UV whilst those longer than 700 nanometers to about 1200 nanometers as IR (Ellen, 200532).. Photographs taken under such light reveal some hidden information that is usually undetectable using naked human eye (Ellen, 200533). The films sensitive to IR and UV wavelengths record and make images that are otherwise invisible to be visible.
Forensic scientists usually apply the use of infrared and ultraviolet imaging in solving of crimes, causes of death. The main uses of UVIR photography include Revelation of forgeries, obliterations, and alterations that are present in documents (Ellen, 200534).. They are also used in other fields other than forensic document examination in revealing of hidden details of a document.
Physical test
This involves the physical examination of documents in question with the aim of identifying any significant differences that may exist between a standard reference document and the document in question. Basically, this is what may include analysis of a paper type, thickness, size and colour. Other physical features usually those visible to the eye are subject to physical examination. Usually physical tests may include reconstruction of damaged and shredded documents. Under these tests, the document is examined for with the aim of detecting and deciphering alterations, erasures and any obliteration present.
ESDA
These are electrostatic detection apparatus which are generally used to detect the presence of indentations in a document as well electrostatic writing impressions caused by other documents having been written while resting on top of the another.
This technique offers information regarding
The history and source of a document.
Documents association to other documents.
Information regarding production sequence of writing of documents.
Identification of cases where documents are produced in mass.
Identification of documents that are unrelated and were written on top of each other.
Impressed tracing guidelines identification around inked signatures.
However, some conditions can make these techniques ineffective hence the need to take the following precautions
Little handling of document as the fingerprints may destroy any writing impressions that may have been present.
Chemical finger printing agents should be avoided prior to ESDA taking place.
Excessive humidity and liquids should be avoided.
Preferably, the document should be sandwiched between two sheets of paper within either a plastic or paper wallet of which should not be written upon.
Generally, this is a highly sensitive technique which not only reveals the immediate page but shows up to two four pages above the one under investigation.
Thin Layer Chromatography and other chemical processes
This is basically a technique that is used to separate mixtures. A sample is applied to a plate after which a solventsolvent mixture is applied to the plate. Through capillary action, the various substances present ascend the plate at different rates thereby enabling separation. This technique is usually applicable in forensic document examination in analyzing whether the ink used for a given disputed document is similar to that used on the standard document upon which comparison is based. This is achieved by identifying whether the components of the inks are the same.
While it has many other purposes, its main functions in forensic document examination include identifying compounds present in a given substance e.g. inks and analysis of dye composition of fibers in forensics
Microscopy
This involves use of high powered microscopes to study the fine details of a document. The microscope magnifies the fine details e.g. signatures to enable the examiner to note any small alterations and differences that may exist in the detail. These details observed are then compared to those present in the document being used as the standard measure of comparison.
Oblique light
The technique just like its name involves projection of light in an oblique perspective. It can be arguably termed as the photography of indented impressions but in this case consideration is taken regarding the fact where there exist parts that lie parallel to the direction of the oblique light cast which cast little shadow there by giving imperfect images (Singla, 1990214). Such impressions can however be photographed through the projection of two sources of oblique light at right angles to each other. These results to the negatives being prepared being superimposed in the enlarger hence produce a more visible final print. This technique too can be used in order to make visible some fine details of a document under examination which would otherwise not have been visible.
Electronic Imaging
This system applies the use of specific software which ahs the ability to detect images imprinted in document which are other wise not visible in the eye. Basically its applicable I case where the standard document possesses such imprinted images. The document in question is then tested to find out if it bears the same images as the original standard one. Usually these images are imprinted using a standalone hard-drive duplicator or software imaging tools.
Visual
This involves use of optical devices to analyze the fine details of the document under examination. Te optical devices allow for viewing of fine details that would otherwise be invisible.
Shading
This involves analysis of a document using various techniques available toe establish any difference in shading that may be present in the document in question while absent in the standard document of measure and vice versa.
DEVICES USED IN FORENSIC DOCUMENT ANALYSIS.
ESDA (Electrostatic Detection Apparatus)
This is equipment used in revealing of indented impressions on paper which would otherwise be invisible (Ellen, 200536). This apparatus are usually nondestructive and allows fro further testing of the document. The machine is sensitive and is capable of detecting fresh finger prints from a document. A good case in where handwritings of two persons mix, ESDA can be used to differentiate in pressures applied by the individuals in writing of the paper hence separation of one handwriting from another.
SEM (Scanning Electron Microscope)
The scanning electron microscope is a device used to scan a finely focused beam of electrons onto a sample under investigation. The impinging electrons produce a series of measurable electron energies which are analyzed using a sophisticated microprocessor that creates a pseudo three-dimensional image or spectrum (Ellen, 200539). The spectrumimages possess unique elements of the sample under analysis. These elements are put under analysis and energy content generated. These are then put into comparison by the results obtained from the standard document.
VSC (Visual Spectral Comparator)
The machine utilizes varying light sources of varying wavelengths in order to distinguish between different inks. While the inks may look identical to naked eyes, possess distinct behaviors that help distinguish them from each other when viewed under a variety of light sources of different wavelengths (Dwayne, 200912). A good example was the case where in analyzing an alleged suicide note it was observed that under certain conditions presented by VSC, the ink used in the note became luminescent unlike the ink that was found from the black point found in the room. The analysis in this case helped identify that the ball point could not have been used.
EM (Electron microscope)
Though expensive, its an efficient gadget in analysis of fine elements of documents being compared. It helps determine finger prints that lie underneath ink in a document or even on top of the ink. With regard to the fact that ink will flow depending on the nature of paper and the finger prints on the paper. Different kinds of ink flow differently on top of finger prints as compared to bank unwritten paper. An electron microscope can be used to identify these fine details and even in some instances it can observe a finger print on top of another finger print.
Advanced UV and IR D-SLR
These are digital D-SLRs custom modified to be used in forensic and scientific use. They are able to work under both UV an IR light thereby capture certain details of a document that are otherwise not available to the normal eye (Brian, 200316). It possesses Super CCD SR II image sensor which ahs a greater dynamic range as compared to the single pixel sensors (Brian, 200316). They also have very low noise. This enhances capturing of fine details both in shadows and in the lights thus uncovering evidence not visible to the normal human eye.
Both these characteristics are crucial for those who need to capture fine detail in both the shadows and highlights in order to uncover evidence not visible to the human eye.
Magnifying glass
These are convex lenses that produce a magnified image of an object. Its basically used to critically analyze features of a document that is under examination.
Stereo microscope
This microscope applies the se of two separate optical paths, two objectives and two eye pieces which provide slightly different viewing angles to the left an the right eyes(Brian, 200315). Given that each eyes views a different image , it is an appropriate tool for use in comparison of specimens and analyze them to note any differences that might exist between the two namely the document in question specimen and the specimen fro the standard document..
Digital microscopes
These microscopes possess ability to be directly connected to the computer via a USB cable thus is sometimes referred to as USB microscopes (Brian, 200319). The images observed can be directly stored in the compute and stored just like other images. They offer high magnification hence the detailed elements of the document can be easily observed and compared to those of the standard document being used for comparison.
In conclusion it will be important to note that over time other devices continue to be built all aiming to be able to reveal many other fundamental features that are always present in various documents yet not visible to the human eye. Forensic examination generally borrows from other applied science disciplines principles in its attempt to solve queries regarding documents in question.
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