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
Introduction Page 5
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.