ch 17 document examination s

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Chapter 17

Document Examination


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Forensic ScienceRichard Saferstein

2009 Pearson Education, Upper Saddle River, NJ 07458.All Rights Reserved.2

Introduction

Any object with handwriting or print whose source orauthenticity is in doubt may be referred to as aquestioned document.

Document examiners apply knowledge gathered

through years of training and experience to recognizeand compare the individual characteristics ofquestioned and known authentic writings.

For this purpose, the gathering of documents ofknown authorship or origin is critical to the outcomeof the examination.

The uniqueness of handwriting makes this type ofphysical evidence one of the few definitive individualcharacteristics available.


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Handwriting Theory

yHandwriting is just as unique as yourfingerprints.

y

Difference between fingerprint andhandwriting

yFingerprints are permanent and do notchange

yHandwriting is a learning process andlends itself to change as a normalprocess


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The Learning Process

y Child is taught using the model of alphabet

y Manuscript Writing

y C

ursive Writingy Child does not have handwriting of his own because

he is creating an artistic representation

y Child gets better at remembering letter

formations and now draws them from memoryy This is where variations and deviations come from and

he/she begins their own handwriting.


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The Learning Process

y Its not until individual characteristicsbecome habitual and repetitious that

handwriting has become mature.yWhen the person can write as a sub-

conscious act.

yThis is where we can make the comparisonfrom fingerprint to handwriting.

y Just as there are no 2 fingerprints thesame, handwriting is also unique.


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Character of Handwriting

Document experts continually testify to thefact that no two individuals write exactlyalike.

Many factors comprise the total character ofa persons writing.

The early stages of learning handwriting arecharacterized by a conscious effort to copystandard letter forms.

However, as writing skills improve, nerve and

motor responses associated with the act ofwriting become subconscious. The unconscious handwriting of two different

individuals can never be identical.


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Variations are expected in angularity, slope, speed, pressure,letter and word spacing, relative dimensions of letters,connections, pen movement, writing skill, and finger dexterity.

These are called natural variations. An individuals signature willnever be totally identical each time he/she signs his/her name.

If two signatures are totally identical, this would indicate a forgery

by tracing the signature.

Other factors to consider include the arrangement of the writingon the paper, such as margins, spacing, crowding, insertions,and alignment.

Spelling, punctuation, phraseology, and grammar can be

personal and help to individualize the writer. Furthermore, the writing style of one individual may be altered

beyond recognition by the influence of drugs or alcohol.


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Letter written by Albert Einstein in German


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Bill Clinton letter


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No single handwriting characteristic can initself be taken as the basis for a positivecomparison.

The final conclusion must be based on a

sufficient number of common characteristicsbetween the known and questioned writingsamples.

There are no hard and fast rules for a

sufficient number of personal characteristics;it is a judgment call made by the expertexaminer in the context of each case.


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Class Characteristic in Handwriting

yClass Characteristics are similaritiesbetween individuals who learned the sametype of writing systems.

yServe just to narrow down the searchwhen comparing a questioned documentto standard writing systems.

yHandwriting systems: Palmer, Zaner-Bloser, and Spencerian


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Individual Characteristics

yThese are characteristics that are true onlyto a specific writer.

y

It is a combination of individualcharacteristics that make handwritingunique to him/her.


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Types of Individual Characteristics

y Skill Level

y Slant

y Form

y Movementy Proportions

y Height

yI Dot

yt Crossing

y Loops

y Pressure

y Baseline Alignment

y Pen Lifts

y Speed

y Embellishmentsy Entry/Exit Strokes

y Retracing

y Spelling/Spacing

y Format

y Case


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Skill level

yThe way a writing looks.

y Important characteristic of identification or

non-identification.yHigh skill level VS Low skill level


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High Skill Level


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Low Skill Level


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Slant

yThis is the angle of writing and can beforward or backward.

y

This alone is not a good basis forjudgment.

yForwards and backward slants are notindicative to handedness.


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Form

y Most basic individual characteristic and is veryimportant to QDE.

y Form is the way a writer makes a letter or

movement of letters.


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Movement and Pressure

y Movement is the way a pen moves in order tomake a mark or form a letter

y This can help distinguish the difference in form.2 letters can be the same, but made in adifferent way.

y Pressure is the difference in ink or pencil in widthor shade. Helps show direction of movement.


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Proportions, Height, &

Loopsy Proportions is thesymmetry of anindividual letter

y Loops are similar toproportions

y Height is the comparingthe height of one letter

to anothery Height, proportions are

usually habits found ina specific writer.


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The I dot and t crossing


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Baseline Alignment

y The value of this show the questioned writing incorrelation to the baseline

y Helps QDE examiners determine whether the

writing was altered or is consistent with the restof the writing or other examples


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Speed

y The speed of a writer is a key indicator for QDEin the examination process.

y Fast and slow speeds are difficult to duplicate

leaving behind inconsistencies in the writing.


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Handwriting Exemplars

The collection of an adequate number ofknown writings (exemplars) is most critical fordetermining the outcome of a handwritingcomparison.

Known writing should contain some of thewords and combination of letters present in thequestioned document and be adequate innumber to show the range of natural variationsin a suspects writing.

The writing implement and paper should alsobe alike. The writing of dictation and several pages may

serve to minimize attempts at deception.


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Typewriters and Printing Devices The two requests most often made of the

examiner in connection with the examination oftypewriters and printing devices are: whether the make and model of the typewriter and

printing devices used to prepare the questioneddocument can be identified.

whether a particular suspect typewriter or printingdevice can be identified as having prepared thequestioned document.

In order to do this, the individual type charactersstyle, shape, and size are compared to acomplete reference collection of past and presenttypefaces.


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Machine Analysis

Typewriters/printers

can leave individualmarkings

Can be class

characteristics orindividual characteristics

Questioned Documents


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Characteristics From Use

As is true for any mechanical device, use of aprinting device will result in wear and damageto the machines moving parts.

These changes will occur in a fashion that isboth random and irregular, thereby impartingindividual characteristics to the printing device.

The document examiner has to deal withproblems involving business and personalcomputers, which often produce typed copies

that have only subtle defects. Another area of investigation relates to the

typewriter ribbon, which may contain typeimpressions.


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Digital Technology

In the cases of photocopiers, fax machines, andcomputer printers an examiner may be calledon to identify the make and model of amachine or to compare a questioned documentwith test samples from a suspect machine.

A side by side comparison is made between thequestioned document and the printedexemplars to compare markings produced bythe machine.

Examiners compare transitory defect marks, faxmachine headers, toner, toner applicationmethods, and mechanical and printingcharacteristics.


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Alterations

Document examiners must deal with evidence that hasbeen changed in several ways, such as throughalterations, erasures, and obliterations.

Erasures by rubber erasers, sandpaper, razor blade orknife to remove writing or typing disturb the fibers ofthe paper and are readily apparent when examinedwith a microscope.

If an alteration is made to a document with ink differingform the original, it can sometimes be detected due todifferences in the luminescence properties of the inks.

Obliteration of writing by overwriting or crossing out tohide the original writing can be revealed by infraredradiation, which may pass through the upper layer ofwriting while being absorbed by the underlying area.


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Ink Analysis (alterations)

Alternative lighting may indicate alterations

with different ink.


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Ink Analysis (alterations)

Alternative lighting may indicate alterations

with different ink.


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A special instrument for document examination is a

UV/IR spectral comparator which makes use of

electromagnetic wavelengths and various filters todifferentiate inks and reveal hidden material on

documents.


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Other Problems

Infrared photography and reflecting light at differentangles are sometimes successfully used to reveal thecontents of a document that has been accidentally orpurposely charred in a fire.

In certain situations, indented writings (partially visibledepressions underneath the visible writing) have

proved to be valuable evidence. It may be possible to determine what was written by

the impressions left on a paper pad.

Applying an electrostatic charge to the surface of apolymer film placed in contact with a questioneddocument will visualize indented writings.


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Alterations

y Overwritingy Erasures

y Crossing out of words (most obvious)

y Must be recognized and characterized

y These are efforts intended to alter orobscure the meaning of thedocument in question

y Must be able to reconstruct thewritten contents of charred or burnedpaper

y Uncover the meaning of indentedwritings found on a paper pad afterthe removal of the top sheet


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Ink and Paper Comparisons

A study of the chemical composition of the inkused on documents may verify whether or notknown and questioned documents wereprepared by the same pen; and the paper itselfmay be analyzed.

A nondestructive approach to comparing inklines is accomplished with a visible-light

microspectrophotometer. Thin-layer chromatography is also suitable for

ink comparisons.


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Ink Analysis (matching pens, etc.)

An ink will have

specific chemicalcomponents.

The same ink can be

used in many pens.(even different brands)


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Look at under

alternative light(different wavelengths)

UV and Infrared light

Glow, Transparent, Nothing


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Look at under

alternative light(different wavelengths)

UV and Infrared light

Glow, Transparent, Nothing


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Thin Layer Chromatography (TLC)

Place punch of ink in solvent

Drop on paper (stationary phase)

Put in liquid (mobile phase)

Liquid travels up paper;

separates components of ink


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Thin Layer Chromatography


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Testimony of Document Examiners

y Has been accepted in courts for 100 yearsy 1989: article challenged the use of expert

handwriting testimonyy

United States v. Starzecpyzel (1995): court ruledthat document examiners provide technical (notscientific) testimony

y 1997: study found that trained documentexaminers were more proficient than nonexperts

y United States v. Paul (1999): upheld the use ofexpert handwriting testimony and the exclusionof the testimony of a person without specifictraining in document examination