CHAPTER-1. Introduction

Transcription

1 CHAPTER-1 Introduction

2 INTRODUCTION Forensic science is the application of various fields of science and technology to investigate and establish facts of interest in a legal system. The discipline of forensic science is divided into two parts. The word forensic comes from the Latin word forēnsis, meaning "of or before the forum." and the word Science Comes from Latin word scientia, meaning "knowledge" which is a collection of systematic methodologies used to increasingly understand the physical world and nature (Houck, 2010). Forensic science is a multiple disciplinary subject which uses the knowledge of computer science, chemistry, DNA analysis, serology, physics, anthropology, toxicology, pathology, entomology, botany, psychology, biochemistry, engineering, digital techniques and linguistics etc which individually or in combined gives rise to specialized areas of forensic science such as computer forensics, forensic chemistry, forensic DNA analysis, forensic serology, forensic physics, forensic anthropology, forensic toxicology, forensic pathology, forensic entomology, forensic botany, forensic psychology, forensic biochemistry, forensic engineering, forensic digital techniques, forensic linguistics and forensic document examination. Forensic investigation is usually carried out in multiple steps by applying various fields of science and technology. Evidence collection is the first and foremost step of any forensic investigation. The collection of evidence is based on the fact that every contact leaves a trace". In its broadest form it states that when two objects come into contact with each other they exchange trace evidence. This basic principle of forensic science is known as Locard s Exchange principle (Newton, 2008). It is formulated by Dr. Edmond Locard and others work,that explains this principle of exchange as wherever he steps, wherever he touches, whatever he leaves, even without consciousness, will serve as a silent witness against him. Not only his fingerprints or his footprints, but his hair, the fibers from his clothes, the glass he breaks, the tool mark he leaves, the paint he scratches, the blood or semen he deposits or collects. All of these and more bear mute witness against him. Physical evidence cannot be wrong, it cannot perjure itself, it cannot be wholly absent. Only human failure to find it, study and understand it, can diminish its value" Introduction Page 1

3 (Kirk, 1974). The analysis of collected evidence reveals the truth in order to provide justice. In the legal process the forensic evidence is considered to be most reliable compared to eye witnesses. Document Section 3 of Indian Evidence Act, 1872 defines document as Any matter expressed or described upon any substance by means of letters, figures or marks, or by more than one of those means, intended to be used, or which may be used, for the purpose of recording that matter. In the broad sense a document may be defined as anything that bears marks, signs, or symbols which have meaning or conveys a message to someone. Classification of Documents Usually, a document is written, but a document can also be printed and can be made with pictures and sound. Documents are generally paper based. The important documents which affect our day to day lives may be classified into following categories: Civil Documents: Birth Registration Certificate, Death Certificate, Marriage Registration/ Divorce Certificate etc. Routine Documents: ID card, Voter ID Card, PAN Card, Domicile Certificate, Caste Certificates, Ration Card, Examination Mark Sheets/ Degrees/ Certificates/ Testimonials, Motor Vehicle Registration Certificate, Driving License. Travel Documents: PASS PORT, VISA, Nationality Certificate, Resident Alien Card, Permanent Resident Card, Naturalization and Citizenship Certificates. Bank Documents: Cheques, Drafts, Traveler Cheques, Currency Notes, Credit Card, Debit Card, Smart Card. Security Documents Executed On Stamp Papers: Demand Promissory (DP) Note, Hypothecation/ Bank Guarantee etc., Agreement, Property Transfer/ Registration etc. Judicial Documents: Important Court Orders/ Judgments, Laboratory Reports. Commerce Related Documents: Patents and Copy Rights Certification, Logo etc. Introduction Page 2

4 Paper-Less or Digital Documents: Electronic Money Transfers through Websites, Online Transactions, e-banking Solutions etc. Depending on the technology used to produce the documents are classified as handwritten, typed, photocopied and printed. Handwritten Documents:- These documents are produced by individuals using writing instruments and materials. Many styles are used in handwritten documents over centuries. Writing instruments include pens, pencils, inks and marker. Typed Documents:- Typed documents are produced using typing machine. Typed documents vary depending on the typefaces of the machine. Each type machine has type letters particular to that machine. They will have specific physical features depending on the make of the machine. Photocopy (Xeroxed) Documents:- Photocopied documents are produced by copying original printed or handwritten documents by electro photography procedure. Photocopied documents look similar to printed document for the untrained eye. Photocopiers are machines, which produce documents similar to the original documents. Photocopiers, like laser printers are electrostatic machines in all respects, the only difference being that laser printer produce grid pattern in document. Most of forged documents like counterfeit currency are produced using colour photocopiers or colour printers. Printed Documents:- The Printed documents are produced using various printing mechanisms. Printed documents contain features of a printer depending on 1) The specified procedure used by them for placing the marking material i.e. ink on the paper e.g. Dot matrix, Laser, Inkjet etc. 2) Inks or toners used in that process. Printed Documents differ in the print pattern, number of drops per dot and technology used to print, like Drop on demand thermal printing, Inkjet technology, Laser technology etc. Printing instruments commercially available in market today are inkjet printers, LaserJet printers and offset printers. Introduction Page 3

5 Questioned Documents The documents whose authenticity or source is suspected or questioned are called Questioned documents. A "Questioned" document is any signature, handwriting, typewriting or other mark whose source or authenticity is in dispute or doubtful. Usually the written, printed or typewritten documents are the most common questioned documents, although marks on doors, walls, windows or boards would also be considered as questioned documents. Document Forensics Document plays an important role in everybody s life. Document affects our lives from birth till death e.g. the documents like birth certificate, identity card, bank transactions and death certificates are used throughout the life of a human being. Any modification in any part of document alters its meaning resulting in the loss to one of the involved party. Document Forensics is the discipline of forensic science pertaining to documents that are disputed in a court of law. A document examiner is often asked to answer many questions such as the origin of source of document. The standards of the American Society for Testing and Materials, International (ASTM) states that an examiner "makes scientific examinations, comparisons, and analysis of documents in order to: establish genuineness or non genuineness or to expose forgery or to reveal alterations, additions or deletions, to identify or eliminate persons as the source of handwriting, identify or eliminate the source of typewriting or other impressions, marks/ relative evidence, and write reports or give testimony, when needed, to aid the users of the examiner's services in understanding the examiner's findings (ASTM E444-09). Document forensics is the field that has emerged to assist the interpretation of evidence in courts which deals with getting evidence from the questioned documents. Ink is a liquid or paste used to colour a surface to produce an image, text or design. Ink is used for drawing or writing or printing with a pen, brush, quill or printer. Ink has existed since it was used in the ancient world, for example in Ancient Egypt for writing on papyrus. These early inks used a carbonaceous compound base and they can be divided into sepia inks (secretions from species of cephalopoda including Sepia officinalis) and Indian/Chinese inks (carbonized organic substances). Such inks were in common use until approximately the twelfth century. Carbon inks are still in use today, but only for specialized Introduction Page 4

6 purposes and not for general writing or printing. In the early twelfth century, iron-gallotannate inks (nutgalls and tannin) became popular, although there is ample evidence that they were in use at a much earlier date. These inks combined with iron salts (ferrous sulphate) were blue or bluegreen. Over the centuries there have been numerous changes in ink formulation, for example the elimination of corrosion. Today inks for fountain pens tend to be either water based or glycol based. Vanadium (late nineteenth century) and aniline dye (invented 1861) inks are no longer in common use. In most fountain pens virtually any properly made writing ink can be used, even though many pen manufacturers try to promote sales of their own label ink. As a point of curiosity, the original meaning of blue-black ink (invented in 1834 by Henry Stephens [England]) was not a description of a colour, but rather of a process. The ink was blue (in the Stephens ink because of indigo) upon writing, but later after oxidation it turned black. Characterization of early ball-point pen inks is clear. Until 1950, all inks had washable dyestuffs or iron gallotannate and oil-based solvents ushered in the era of glycol-based inks (ethylene glycol). Sometimes rosin or rosin acid was used to improve viscosity. Only in 1953, however, ball-points became a popular item with the writing public. Copper phthalocyanine dyes (copper phthalocyanine tetrasulphonic acid) were introduced into inks experimentally in 1954 and commercially soon thereafter. Some problems with the original ball-point inks were slow drying, broadening of written lines during the drying process, fading, and smudging. Second generation ball-point inks are composed of a solvent (glycol or polyalcohol), a colouring agent, anti-corrosives, waterproofing, and private materials (which give commercial uniqueness to the product, such as anticoagulants). To improve the ink characteristics the modern inks are now containing many substances like dyes, pigments, vehicles, surfactants, resins, lubricants, solubilizers, particulate matter, fluorescers, humectants, driers, plasticizers, waxes, greases, soaps and detergents etc. Each component serves as different purposes like dyes or pigments are used as a colouring material. The colouring material may be dye or pigment or might be their combination. Dyes are soluble in the liquid body of the ink i.e. vehicle. Pigments are insoluble in vehicle as they are finely grounded multi-molecular granules. The composition of vehicle affects the flowing and drying characteristics of the ink. The main aim of most analyses is to determine whether two Introduction Page 5

7 pieces of written/printed material originated from the same ink. The comparison of different writing/printing inks on a document is the main goal of the most investigations. The major classes of ink which may encountered in analysis are ballpoint pen ink, roller-ball pen ink, fibre tip pen ink, marker ink, fountain pen ink, porous-tip pen ink, plastic tip pen ink, gel pen ink, rubber stamp ink, dye pack, offset printer ink, letterpress ink, typewriter ink, copier/printer toner and inkjet inks. Generally inks could be in aqueous, liquid, paste or powder form. Some of the inks are classified and discussed below depending on the writing/printing instrument:- Fountain pen inks There are two types of fountain pen ink iron gallotannate type and aqueous solution of synthetic dyes. Modern inks of type two contain synthetic blue dyes to provide an immediate blue colour to which gradually turns black after oxidation on paper. This explains the origin of the name blue-black fountain pen ink. This class of ink is also very stable. This ink is insoluble in water and cannot be effectively erased by abrasion. The most popular fountain pen ink (developed in the 1950) consists of an aqueous synthetic dye. These inks are bright and attractive in colour, but they are not nearly as stable as the carbon blue-black inks. Some of the synthetic dyes used fade and soluble in water. The most modern ink of this type contains pigmented dyes, such as copper phthalocyanine (introduce in about 1953) which makes these inks much more permanent. Ballpoint pen inks The ballpoint pen developed in Europe about 1939 and was initially distributed in Argentina about In 1946, several million Reynolds ballpoint pens reached the market in the united state (Ryan et al., 2006). Ballpoint pen inks consist of synthetic dyes (sometimes carbon or graphite is also added for permanence) in various glycol solvent or benzyl alcohol. The dyes in ballpoint inks can consist of up to 50% of the total formulation. Several other ingredients are usually added to the ink to impart specific characteristic. These ingredients consist of fatty acids, resins, surface active agents, corrosion control ingredients and additives similar to those in rolling ball marker inks and fountain inks. The water based inks are obviously water soluble, where as the xylene based inks are water resistance and can only be dissolved with strong organic solvents. Formamide or glycol solvents Introduction Page 6

8 are essential ingredient in fiber tip inks to keep the fiber tip from drying out. Fiber tip inks that contain metalized dyes are light fast. Gel pen ink The most recent development in the writing instrument industry is the introduction of the gel pen by the Japanese. Four brands of gel pen have been introduced. (1) the Uni ball signo by Mitsubishi ;(2) the zebra j-5; (3) the pentel Hybrid; and (4) the sakura Glly roll pen. These pens have been marketed by the Japanese since the mid-1980s and a limited supply of the pens was sold in the United States about Gel inks contain completely insoluble coloured pigments rather than organic dyes. Writing with ink is very similar to the appearance of the writing with a ballpoint pen. This ink, which is water based, is a gel and not a liquid. It is insoluble both in water and strong organic solvents. This physical property makes it impossible to analyze (by traditional method) for the purpose of comparing two or more inks of this type. Dye Pack Dye pack is a red stain used to mark stolen currency. It is a radio-controlled incendiary device used by some banks to preemptively foil a bank robbery by causing stolen cash to be permanently marked with dye shortly after a robbery. Dye pack contains 1- methylaminoanthraquinone (MAAQ) as well as other dyes. Printing Ink In the past centuries the printing industry could be discussed very precisely due to the existence of only one or two printing process. Today the scenario is very different. These days the technology is getting advanced day by day and the role of printer is changing. The fast growing changing environment causes the printer to keep on changing as per the requirement and also the printing ink. All of the major and minor components of ink determine the end behavior of the print quality. An effective printing ink must meet both press and print requirements. In printing inks, four different colours of ink are employed: cyan, magenta, yellow and black. All other colours can be Introduction Page 7

9 formed by overprinting these inks, e.g., red is produced by overprinting yellow and magenta, as the yellow absorbs the blue light (because yellow is the emission of red and green light) and magenta absorbs the green light, leaving behind pure red light. Cyan (aqua or blue-green), magenta and yellow add together to give brown colour usually. Printing inks are formulated to transfer and reproduce an image from a printing surface in order to convey a massage, to give a decorative effect to the substrate or to serve many other purposes. The printing film thickness will depend upon the process used which is usually between 2 and 3 µm. Colour printing inks primarily consist of linseed oil, soybean oil, or a heavy petroleum distillate as the solvent (called the vehicle) combined with organic pigments made up of salts of nitrogencontaining compounds (dyes), such as yellow lake, peacock blue, phthalocyanine green, and diarylide orange. Inorganic pigments (used to a lesser extent) in printing inks include chrome green (Cr O ), Prussian blue (Fe [Fe(CN) ] ), cadmium yellow (CdS), and molybdate orange White pigments, such as titanium dioxide, are used either by themselves or to adjust characteristics of colour inks. Black ink is made using carbon black. Most red writing inks are dilute solution of the red dye eosin. Blue colour can be obtained with substituted triphenylmethane dyes etc. Copier/Printer toners Toner is a powdered ink used in laser printers and photocopiers. Earlier toner was a mix of carbon powder, iron oxide and other components. Photocopier and laser printer toners typically consist of resins; cross-linking agents (compounds having two or more double bonds capable of polymerizing); binding agents; carriers; various additives and with colour laser copiers/printers, colouring agents. The carbon was melt and mixed with a polymer. Toner particles are melted by the heat of the fuser, and bind to the paper. The specific polymer used varies with manufacturer but can be a can be a styrene acrylate copolymer, a polyester resin, a styrene butadiene copolymer, or a few other special polymers. Toner formulations vary from manufacturer to manufacturer and even Introduction Page 8

10 from machine to machine. Typically formulation, granule size and melting point vary the most. Toner has traditionally been made by compounding the ingredients and creating a slab which was broken or pelletized, then turned into a fine powder with a controlled particle size range by air jet milling. This process results in toner granules with varying sizes and aspherical in shape. To get a finer print, some companies are using a chemical process to grow toner particles from molecular reagents. This results in more uniform size and shapes of toner particles. The smaller uniform shapes permit more accurate colour reproduction and more efficient toner use. Modern laser toner cartridges intended for use in colour copiers and printers come in cyan, Magenta, Yellow and Black (CMYK). Toners typically consist of binder resin such as polystyrene, styrene derivative homopolymers, styrene copolymers; magnetic materials like Iron oxides, magnetic metals; Surface treating agents such as Silane coupling agents and titanium coupling agents; Surface active agents such as Sodium dodecyl sulfate and sodium tetradecyl sulfate; Charge Controlling Agents such as Organometallic compounds; flowability improving agents like Inorganic oxides, carbon black, and carbon fluoride; polishing agents such as metal oxides, nitrides, carbides and metal salts; colouring agents like carbon black in black toner, lsoindolinone compounds, anthraquinone compounds for Yellow toner, Condensation azo compounds, anthraquinone compounds, base dye lake compounds, naphthol compounds for Magenta toner, Copper phthalocyanine compounds and derivatives for Cyan toner. Inkjet Inks Inkjet inks are low viscosity fluids, typically 4-30 centipoise and consist of a colourant, solvent, binder and additive. Manufactures are generally reluctant to disclose specific ingredients of their ink product in order to protect their trade secrets. However many research has been done in the past in order to provide the ink formulations and many resources are available to give useful information for commercial as well as forensic point of view. Specific dye and pigment combinations determine the levels of all other chemicals to be used in manufacturing inkjet ink. The colourants in inkjet inks are principally dyes. Pigments must have Introduction Page 9

11 a particle size less than 3 µm. Dyes should be highly soluble in the solvent and should have high thermal stability and light fastness. To control the viscosity for good drop formation and to bind the colourant in order to adhere to the surface to be printed the binders are used in inkjet inks which consist of one or more polymers. Finally various additives are included to modify flow properties and surface energy (which should be >35mN m -1 to produce a well defined stream of droplets). Although there are many variations to the inkjet ink formula, the key ingredient components of this ink are colourant, water, vehicles, humectants, co-solvents, fixative, surfactants, resin, biocides/fungicide and buffering agents. Colourants (dyes or pigments) can vary widely in quality and style. Water soluble dyes in inkjet inks are the major requirement for ink jet printers, since water is commonly the primary solvent and ink components must remain in solution to keep from plugging the jet mechanism. Water, which makes up 50 to 90 percent of the mix, is what dilutes the colourant and other chemicals to make the ink spread thinly and evenly as it is distributed from the cartridge. Dyes such as Food Black 2 are water-soluble. Dyes such as anionic dyes e.g. Food Black No. 1, Food Black No. 2, Food Red No.40, Food Blue No. 1, Food Yellow No. 7, FD and C dyes, Acid Black dyes etc are the renowned dyes used as a colourant in inkjet ink formulation. Inkjet inks comprise of different vehicles such as water and/or ethylene glycol, other derivates of glycol, ethers, amides, urea, substituted ureas, ethers, carboxylic acids and their salts, esters, alcohols, organosulfides, organosulfoxides, sulfones, alcohol derivatives and others. In order to prevent or deter evaporation of the water-based formula co solvent and humectants are used. As evaporation occurs at the print head, the formula and viscosity of the ink can alter unfavorably. To control or prevent this change, humectants, such as glycol, are added to the formula in varying degrees. Other agents and chemicals are blended with the three major components of the ink formula to create a final product that spreads and dries evenly and adheres to the paper without flaws, such as feathering. The purpose of adding biocides, fungicides and buffering agents in inks is to keep the ink free Introduction Page 10

12 from bacteria and fungi that might alter the formula and control the ph balance that is required for long term storage. Carefully monitored levels of fixative and penentrant materials are added to assist with delivery of ink to paper and to control just how much ink adheres to the surface. Surfactants are one of main ingredient of ink control the consistency of the ink, and allow it to flow smoothly through the cartridge. Too little surfactant might cause the ink to gum up inside the cartridge, while too much surfactant would loosen it up and then cause it to drip out. Surfactants such as Alkyl (linear) diphenyl oxide disulphonates etc, are getting used in inkjet inks. To control the durability of the printed character after it has dried on the paper, sometimes manufacturers are using resins. Printing inks are applied by five major printing processes. The main printing processes are: Lithography, flexography, gravure, letterpress, screen printing, toner printing systems and inkjet printing. Some of the minor printing processes are intaglio or recess printing and collotype which are rarely used except for special purpose. Out of all printing processes inkjet printing is common, economical and most used today for commercial and personal use. Printing Media The computer processed documents are printed onto paper by Laser, Inkjet, Dot Matrix Printers, etc. In dot matrix printer, each character is represented by a pattern of dots, and a set of the fine needles is activated by data from the computer to construct the shape of the relevant character by striking through a ribbon held against the paper. Laser printers contain a photosensitive drum which, when it becomes charged, produces an electrostatic negative of the image to be printed. Negatively charged toner sprinkled on the drum will cling to the charged areas before being pressed on the sheet of paper, producing the document whereas inkjet printing generate image by the means of non impact using computer control. It directs small droplets or particles in rapid succession on to the surface of a substrate under computer control. There are various possible ways of generating and projecting droplets in inkjet printing such as continuous inkjet (CIJ) and Drop-on-demand (DOD). Ink jet printers use grids of tiny nozzles which, when heated, drop ink onto the paper. Ink jet printers often produce print with somewhat Introduction Page 11

13 ragged appearance which is easy to spot. Though it is easy to recognize documents produced by ink jet printers, it is not easy to differentiate between the documents produced by inkjet technology and others. Ink Analysis Just because a document appears to have been written throughout in the same ink does not mean it has not been altered or added to. With the advance technologies criminals find various ways to alter the document which become almost impossible to identify by the naked eyes. Knowledge of the composition of ink is necessary to distinguish the different inks used to produce a fake document and to compare various inks to identify the source of the printed document. Ink analysis is an important part of the investigation of questioned documents, including forged cheques, wills, altered records, counterfeit currency, anonymous letters, driving licenses, contracts, voter registrations, passports, petitions, threatening letters, suicide notes and lottery tickets etc., although inks from different companies may look the same, there can be some important differences in their chemical composition. These can be revealed by laboratory analysis and the results can help assess whether there have been any additions or alterations done in a document. Ink analysis does focus on a new chemical and analytical methods or techniques. It is a step to increase the discriminating power of enforcement agencies which can use the advance techniques of ink analysis during their criminal investigations. Preliminary examination of document under microscope can provide informative data. The ink may be analyzed by non-destructive or destructive methods. In case the sample needs to be taken from the document usually the destructive methods are adopted. It is preferable to approach the non destructive methods first so that the document is left intact and as the destructive methods, alter the document under analysis. The main method of non destructive ink analysis is examination of ink using Video Spectral Comparator. The VSC is an imaging device that allows an examiner to analyze inks, visualize hidden security features, and reveal alterations on a document. It involves recording of spectra under transmittance, absorbance and reflectance mode based on the amount of light transmitted, absorbed and reflected respectively. Each ink should give a spectrum. The spectrum of the ink on Introduction Page 12

14 the document can therefore be compared with the spectra of standard inks. The microscopic analysis of document by Fourier Transform Infra Red Spectrometry can also provide valuable and distinguishable data for various types of ink. The coupling of Scanning Electron Microscope along with Energy-dispersive X-ray Spectrometry (SEM-EDX) is another non destructive analytical technique used for the elemental analysis or chemical characterization of ink. SEM provides detailed high resolution images of the sample by rastering a focused electron beam across the surface and detecting secondary or backscattered electron signal whereas EDX provides elemental identification and quantitative compositional information about the sample. Where there is not possible to gather the information about the ink from non destructive analysis the destructive methods can also be employed. The main method of destructive analysis of ink is Thin Layer chromatography (TLC). In reality, it is not very destructive to the document if done with care. However, a photographic record of the original document is taken before the procedure is started. A tiny sample of the inked paper is punched out using a thin, hollow needle; a hypodermic syringe is ideal. The sample is placed in a test tube with a solvent that dissolves the ink. Next, a tiny spot of the sample solution is placed onto TLC Plate, alongside spots from various reference ink samples. The TLC Plate is placed in a beaker containing a small amount of another solvent. It is positioned so that the plate dips into the solvent but the spots of sample remain dry. The solvent is drawn up the TLC plate through capillary action and the sample spots move up with it. The end result with TLC is a pattern of coloured spots, known as a chromatogram, for each ink. Different inks will have different chromatograms. If the sample ink has the same chromatogram as one of the reference inks, it suggests they are the same, and so identification can be made. Another technique called High Performance Thin Layer Chromatography (HPTLC), is an enhanced form of TLC and can be used as an alternative to it. It involves the application of ink samples and standard on chromatographic plate and developing the plate in suitable solvents. After the chromatographic development it allows the detection and scanning of spots along with the documentation of chromatic plate. Introduction Page 13

15 UV-Visible Spectrometry is another destructive technique to identify what is in a ink. A UV- Visible spectrophotometer is an instrument used to measure the amount of ultraviolet (UV) and visible light absorbed by a solution. Depending on the substance, the chemical absorbs a certain amount of light, which causes electrons to move from one energy level to a higher one. The amount of light that reaches the instrument's detector is then recorded as a spectrum. The elemental analysis of ink can provide excellent distinguishable features for ink. Inductively Coupled Plasma Mass Spectrometry or ICP-MS is an analytical technique used for elemental determinations. The elemental profiling of ink can prove as an effective tool for the analysis of suspected ink and thus its comparison with the profiling of standard inks. Besides all the techniques Fourier Transform-Infra Red Spectrometry is considered to be a very powerful technique. It is used to obtain an infrared spectrum of a solid, liquid or gas based on functional groups of the compound present in sample. An FTIR spectrometer simultaneously collects spectral data in a wide spectral range. Like a fingerprint no two unique molecular structures produce the same infrared spectrum. This makes infrared Spectrometry useful for several types of analysis. Cases encountered in routine Forensic Document Examination- Problems related to Questioned Documents The Forensic Examiners encountered the analysis of following documents in their routine case works: a. Identification of handwritten documents. b. Identification of forged documents. c. Identification of typewriter. d. Deciphering obliterations, alterations and erasures. e. Identification of inks and writing instruments. f. Printer identification of the document. g. Photograph tampering. Introduction Page 14

16 Problems in Printed Documents It has been noted that there is a significant increase in the number of documents prepared by printers, copiers and multisystem function in the past four decades. The extensive access, ease of use, easy affordability of these systems makes it simple to create fraudulent document using a ink and/or toner (e.g. dry or liquid). Examination of printed questioned document plays a major role in the investigation of numerous cases. Though most of the documents are now produced using methods which deter counterfeiting due to the particular coloured fibers, complex patterns, and specialized inks used to produce documents. It makes forgery extremely difficult but still the criminals often attempts to forgery them. Determination of authenticity of different types of documents can give rise to problems of characterizing some of the materials used to produce the document such as ink and/or toner. Determining the brand of printer or copier and/or establishing how a document was produced are major part of verification of authentication of document. Microscopically it is possible to establish how a document was produced to some extent.determination of the brand of printer may involve a chemical analysis of the ink present on the document. In the context of printed questioned documents examination, forensic analyst has to answer the questions like: 1. Is the document consistent, implying whether the content printed in the document is prepared from a single source? 2. Identification of source printer or printing techniques. 3. Are two documents similar, i.e., printed using printer was of same brand? Just because a document appears to have been written throughout in the same ink does not mean it has not been altered or added to. The present work is carried out: Introduction Page 15

17 1. To fix the genuiness of the document: Knowledge of the composition of ink is necessary to distinguish the different inks used to produce a fake document or to compare various inks and to identify the source of the printed document. 2. Although all inks of different companies may look the same, there can be some important differences in their chemical composition. These can be revealed by laboratory analysis and the results can help to assess whether there have been any additions or alterations done in a document. This study is very useful for the source identification of printer used to print extortion /threatening letter as well as to find out whether the particular printer was used to print a suspected document or counterfeit currency. The comparison of two or more ink entries to determine similarities or differences in inks can be carried out with the results presented in this study. This can provide information concerning whether entries have been added or altered. The study is also very helpful to determine whether two or more entries were written with the same formula and batch of ink. This provides a lead whether certain document could have been printed with the same printer or not. Thus, the present study entitled Profiling of Inkjet Printer Inks from Printed Documents by using Instrumental techniques was carried out with the following objectives. OBJECTIVES 1) To develop ink profile of various inkjet printers using instrumental techniques. 2) To categorize different brands of printers based on their ink profile. 3) To compare the ink profiles of different brands used in inkjet printers extracted from documents. Introduction Page 16