Forgery and Counterfeiting

Questioned Documents 2

Criminal Forgery

• Multi-billion dollar business

• Both forensic techniques and detection methods have become very sophisticated

• FBI white collar crime (now along with terrorism) is largest division

• Includes checks, credit card receipts, insurance policies, etc.

Criminal Forgery

• Also clothing, music, electronics, jewelry

• Product counterfeiting estimated to be 5%-7% of world trade– $500 billion each year

• Rampant in the Far East– Taiwan, Singapore, Indonesia

Criminal Forgery

Open air bazaar in Ankara, Turkey.

Detecting Forgeries

Lighting effects– Oblique angles– UV lights

An “invisible” identification marking that is only visible under ultraviolet light.

Detecting Forgeries

• Chemical analysis– Iodine treatment (same as fingerprinting)– pH testing– Ink analysis– UV detection

Detecting Forgeries

• Obliterations– Often involves physically erasing marks or scraping ink

off paper’s surface

• Methods disturb top layers of fiber from paper– Can usually be seen with oblique light under a

microscope

• Chemical obliteration– Certain chemicals can react with ink to make it colorless– Can also be seen with certain techniques

Identifying Paper

• Nature of paper– Actually a blend of wood pulp, cotton or other

materials– “Bond paper”

• 25-50% cotton

– Watermarks• Created by reducing number of fibers

Identifying Paper

• Forensics is interested in:– Raw material– Color– Density– Watermarks– Dyes/bleaches– Fluorescence– Thickness

Chromatography

• Scientific technique used extensively in the identification of chemicals

• A forensic scientist may be able to link the presence or absence of chemicals to a suspect

Chromatography

• Essentially the separation of chemical mixtures and substances

• Technique depends on the fact that different chemicals will be absorbed at different rates by another chemical selected to separate the unknown mixture

Thin Layer Chromatography

• Glass slide is coated with a thin layer of gel• Small amounts of unknown sample are

dotted near the bottom of the slide• Slide is then placed in a liquid so level of

liquid reaches just below the dots on the slide

• As gel absorbs the liquid, it “climbs” up the slide and separates the unknown sample

Gas Chromatography

• More recent technique– Requires computer assistance

• Unknown mixture is vaporized by heat inside chromatograph.

• Vaporized mixture is forced by a non-reactive gas along a narrow, coiled tube

• Different components in gas flow at different speeds and are detected at the end of the tube

• Especially useful in blood alcohol tests, ID of street narcotics and in fire investigation

Gas Chromatography

Gas Chromatography

Paper Chromatography

• Uses a vertical piece of filter or other absorbent paper

• Unknown substance is applied near the bottom of the paper

• Paper is hung with its end in a liquid and allowed to soak

• As the liquid is absorbed by the paper and rises, it will carry some or all of the unknown substance with it creating the chemical “fingerprint”

Paper Chromatography

Gas Chromatography

Paper Chromatography

Paper chromatogram indicating the natural (and possible artificial) dyes of a marijuana sample