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FORENSIC SCIENCE
Unit 7: Questioned Documents and Chromatography
EVIDENCE 1. Class characteristic—ink analysis,
paper analysis, most handwriting analysis
2. Individual characteristic--With document analysis, it is difficult to identify to an individual characteristic except with typewriter or printer specific marks.
QUESTIONED DOCUMENTS Involves the examination of handwriting, ink, paper, etc. to
ascertain the source or authenticity or detect any changes.
Examples include letters, checks, licenses, contracts, wills, passports, suicide notes, receipts, etc.
Topics
Handwriting analysis
Ink (and pens)
Paper (and pencils)
Forgery
Codes and Ciphers
QUESTIONED DOCUMENTS Forensic Document Examiner--involves
the analysis and comparison of questioned documents with known material (exemplar) in order to identify whenever possible, the author or origin of the questioned document.Unfortunately, no federal licensing exists. May also be asked to determine if changes
have been made. Graphologist--attempts to predict
character traits (personality) from handwriting examination
HISTORY Led to the conviction (and execution) of
Bruno Hauptmann in 1930 based on ransom note handwriting.
Has not always been accepted by the courts.
In 1999, the US Court of Appeals determined that handwriting analysis qualifies as “expert testimony” and is admissible provided it follows scientific guidelines.
HANDWRITING Everyone has a unique handwriting style
despite variations that occur due to mood, age, and hurriedness.
Handwriting analysis involves two phases:The hardware--ink, paper, pens, pencils,
typewriter, printersVisual examination
Most frequently requested type of document analysis
There are 12 characteristics that are commonly examined. (RM pages 33-35)
LINE QUALITY Line quality—do the letter flow or are
they deliberate
SPACING Spacing of words or letters—what is the
average space
SIZE CONSISTENCY Ratio of height, width, and size of the
letters—are they consistent
CONTINUOUS Lifting pen—does the author lift his pen
between words
CONNECTING LETTERS Connecting strokes—how are capital
letters connected to lowercase letters
LINE HABITS Strokes to begin and end—where do
they letters begin and end on the page
PEN PRESSURE Pen pressure—how much pressure is
applied on the up and down stroke
SLANT Slant—do the letters slant left or right or
variable
LETTERS COMPLETE Are letters completely formed?
CURSIVE OR PRINTED Are letters cursive, printed, or both
FANCY CURLS OR LOOPS Fancy writing habits—unusual loops or
curls; unique styles
DIACRITICS Placement of diacritics—crossing t’s and
dotting i’s
HANDWRITING ANALYSIS
Goal is to detect forgeries (documents made, adapted, or falsified in an attempt to deceive someone)
“ACE”
Analysis of the “knowns” with a determination of the characteristics found in the known . Exemplars (letters, diaries, cards, personal notes)
Analysis of the questioned or unknown writing and determination of its characteristics
Comparison of the questioned writing with the known writing.
Evaluation of the evidence, including the similarities and dissimilarities between the “questioned” and “known” writing.
OBTAINING HANDWRITING SAMPLES
The subject should not be shown the questioned document.
The subject is not told how to spell words or use punctuation.
The subject should use materials similar to those of the document.
The dictated text should match some parts of the document.
The subject should be asked to sign the text. Always have a witness. Repeat with the non-writing hand. Samples should be both requested and collected.
BIOMETRIC SIGNATURE PADS Recognizes your signature based on
speed, pressure, and rhythm of signing. Slight differences can be detected.
FISH Forensic Information System for
Handwriting Database for handwriting used and
maintained by the Secret Service. Eliminates subjective opinions. Has been used to verify that no two
individuals pen their words exactly the same way.
SHORTCOMINGS Standards aren’t always good.
Sometimes the standard for comparison is a forgery as well.
Effects of mood, age, drugs, fatigue, and illness on handwriting aren’t always predictable.
LINGUIST Experts that look at the linguistic
content (the way something is written) of a questioned document.
Language that is used can help to establish the writer’s age, gender, ethnicity, level of education, professional training, and ideology.
FORGERY OR FRAUD A forgery is the act of falsifying
something with the intent to deceive someone.
Fraud is committed when you profit (some material gain) from a forgery.
CHECK FORGERY Checks can be forged by:
Ordering someone else’s checksDirectly altering a check Intercepting someone’s check, altering it,
and cashing it.Creating forged checks from scratch
CHECK FORGERY Ways to prevent
Checks printed on chemically sensitive paper
Use large font sizeHigh resolution borders that are hard to
copyPrint in multiple color patternsEnhanced fibers that glow under different
lightsUse chemical washes that change colors when a check is altered.
INK Chromatography--physically separate
mixtures of gases, liquids or dissolved solids.
TypesGas ChromatographyHPLC--high-performance liquid
chromatographyTLC--thin-layer chromatographyPaper Chromatography
Gas ChromatographyUsed to determine the chemical composition of unknown substances, such as the different compounds in gasoline shown by each separate peak in the graph below.
Paper ChromatographyCan be used to separate the components of inks, dyes, plant compounds (chlorophyll), make-up, and many other substances
Liquid ChromatographyUsed to identify unknown plant pigments & other compounds.
Thin-Layer ChromatographyUses thin plastic or glass trays to identify the composition of pigments, chemicals, and other unknown substances.
Examples of Chromatography
PAPER CHROMATOGRAPHY WITH INK Two samples of black ink from two
different manufacturers run using paper chromatography.
RETENTION FACTOR
This is a number that represents how far a compound travels in a particular solvent
It is determined by measuring the distance the compound traveled and dividing it by the distance the solvent traveled.
RETENTION FACTOR
BLACK MARKER AFTER CHROMATOGRAPHY
GAS CHROMATOGRAPH Separates mixtures The written record of the results is
called a chromatogram. A typical one will show a series of peaks,
with each representing one component of the mixture.
This allows identification of class characteristics.
MASS SPECTROMETER an instrument that connects to the gas
chromatograph. The substance is exposed to a beam of
high-energy electrons. Fragments then pass through an
electronic or magnetic field where they are separated according to their masses.
No two substances produce the same fragmentation pattern, thus producing individual characteristics.
PAPER
Weight
Color
Water marks
Age (binding agents and chemical composition)
PENCILS
Lead Hardness Scale--a traditional measure of
the hardness of the "leads" (actually made of graphite) in pencils. The hardness scale, from softer to harder, takes the form ..., 3B, 2B, B, HB, F, H, 2H, 3H, 4H, ..., with the standard "number 2" pencil being of hardness 2H.
COUNTERFEITING When documents are copied with the
intent to deceive. The most common are traveler’s checks,
bonds, and currency. Counterfeiting on money is investigated
by the Secret Service.
COUNTERFEITING PREVENTION US currency has specific features to
make it difficult to counterfeit. The number one feature is the special
paper it is printed on. Counterfeit detection markers contain
iodine which reacts with fake money to turn blue-black. Claim to be 98% effective.
1. portrait stands out and appears raised 2. there is micro printing on the security
threads and portrait. 3. serial number is evenly spaced and
same color as treasury seal 4. check letter and quadrant number
5 and 6 Treasury and Federal reserve seals are sharp and crisp.
7. Red and blue fibers throughout and security thread.
8. federal reserve number and letter
9. series 10. check letter and face plate number 11. watermark on right side 12.Colorshift from copper to green. 13. Clear background lines and detail 14. clear distinct border edge
CODES AND CIPHERS
Codes--letter combinations or symbols used to represent words or concepts
Interception from terrorists and other war enemies
Ciphers--a message in which letters or symbols replace the actual letters in the message.
CODE BREAKING TERMS Encipher (to encode)---to hide the
message; top to bottom in a cipher key
Decipher (to decode)---to reveal the message; bottom to top in a cipher key
SHIFT CIPHER Simplest type of cipher. Works by shifting the alphabet a certain
number of places There are 25 possible keys.
CAESAR SHIFT Caesar simply replaced each letter in a
message with the letter that is three places further down the alphabet.
FREQUENCY ANALYSIS If you have got a message you want to
crack, you can use frequency analysis. In other words, if the sender has tried to
disguise a letter by replacing with a different letter, you can still recognize the original letter because the frequency characteristics of the original letter will be passed on to the new letters.
Which letters are the most common in English?
FREQUENCY ANALYSIS
FREQUENCY ANALYSIS These frequencies are averages, and E
will not always constitute 12.7 % of all the letters in a text, and may not even be the most common letter.
The longer the message, the more likely it is that will obey the average distribution shown above. However, there are exceptions to this rule.
