CHAPTER-1

Introduction

Introduction Page 1

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"

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(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.

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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.

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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

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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 blue-

green. 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. 1950 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

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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 1943. 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

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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 1993. 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

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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 nitrogen-

containing 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 (Cr2O

3), Prussian blue (Fe

4[Fe(CN)

6]

3), 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

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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

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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

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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

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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

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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.

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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.

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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:

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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.