Frsc exam 4

Questioned Document

Any document with handwriting or print whose source or authenticity is in doubt and is subject to forensic investigation.

Forensic Document Examination (FDE)

The process of comparing questioned writings to known samples to determine authorship or authenticity.

Handwriting

A unique physical evidence trait—no two people write exactly the same due to subconscious motor patterns.

Exemplar

A known writing sample used for comparison with questioned documents.

Document Alteration

Changes made to a document after its original creation, including additions, erasures, or overwriting.

Indented Writing

Impressions left on paper underneath a page that was written on; often recoverable and used as evidence.

Forgery

Fraudulent imitation or alteration of a document or signature.

Check Fraud

Criminal act of writing bad checks or altering them to illegally obtain money.

Counterfeiting

Illegally imitating currency or other official documents.

Document Authentication

Determining whether a document is genuine or has been tampered with.

Variations in Handwriting

Expected differences in writing such as angle, pressure, spacing, and speed, even in samples from the same person.

Influences on Writing

Factors like drugs, alcohol, and health can alter writing style.

Transmitting Terminal Identifier (TTI)

A header printed by fax machines that can help trace the source of a document.

Mechanical Defects

Wear and damage to printing devices that create unique traits, helping identify the machine used.

Microspectrophotometer

A nondestructive tool for comparing ink lines using visible light absorption.

Thin-Layer Chromatography (TLC)

A method used to compare inks by separating components on a plate.

Infrared Radiation

Can reveal writing underneath obliterations or alterations that are invisible to the naked eye.

Charred Document

A document that has become brittle and dark due to exposure to fire or heat.

Image Digitization

Scanning or photographing a document to convert it into pixels for analysis or enhancement.

Ink Analysis

Chemical examination of ink to determine if documents were written with the same pen.

Obliteration

Overwriting or crossing out text to hide original content.

Video Spectral Comparator (VSC)

Imaging system used to detect tampering, watermarks, ink differences, and hidden features.

Alterations

Changes made to a document using different ink, writing tools, or overwriting original content.

Erasures

Physical removal of writing using tools like erasers, razors, or sandpaper—often detectable by microscopes or lighting.

Document Source Questions

Investigations may ask

Paper Analysis

Comparing paper characteristics such as fiber, watermarks, and texture.

Surface Features

Visual traits of a document surface used to identify tampering, such as ink gloss or impressions.

Pseudo-Science

The false belief that handwriting reveals personality traits—rejected in forensic science.

Historical Cases

Famous uses of document examination include the Lindbergh kidnapping, JonBenet Ramsey ransom letter, and Hitler diaries.

Oxidation

The combination of oxygen with another substance to produce new substances, often releasing energy.

Energy

The ability of a system to do work; can take forms such as heat and light.

Exothermic Reaction

A reaction that releases more heat energy than is required to initiate it.

Ignition Point

The minimum temperature needed to spontaneously ignite fuel.

Heat of Combustion

The energy released as heat and light when a substance burns.

Fire

A chain reaction that sustains itself through heat, fuel, and oxygen.

Flash Point

The lowest temperature at which a liquid gives off enough vapor to ignite.

Pyrolysis

The decomposition of solid materials by heat to produce flammable gases.

Glowing Combustion / Smoldering

Burning at the fuel-air interface, like in cigarettes or embers.

Conduction

Heat transfer through a solid object (e.g., metals in structures).

Radiation

Heat transfer by electromagnetic waves (e.g., paper igniting at 451°F).

Convection

Heat transfer through movement in gases or liquids (e.g., hot air rising).

Accelerant

A substance used to speed up the spread of fire (e.g., gasoline, kerosene).

Streamers

Materials used to intentionally spread fire from one area to another.

Point of Origin

The location where a fire began, typically showing the most intense burn and located lowest.

Ignition Device

Tool or object used to start a fire (e.g., matches, cigarettes, Molotov cocktails).

Flashover

When all combustible materials in an area ignite at once, engulfing a structure in fire.

Substrate Control

A control sample of similar but uncontaminated material collected at a fire scene.

Headspace

The vapor area inside a sealed container that holds debris samples for accelerant detection.

Charcoal Strip Method

A technique using charcoal to absorb vapors from fire debris for lab analysis.

Gas Chromatograph (GC)

An instrument used to separate and analyze chemical substances in fire debris.

Hydrocarbon

A compound made of only carbon and hydrogen; common in fuels and accelerants.

Ignitable Liquids Reference Hydrocarbon Collection (ILRC)

Online resource of chromatographic patterns for known accelerants.

Explosion

A chemical or mechanical reaction that produces heat and rapid gas expansion.

Explosives

Substances that undergo rapid oxidation to release gas and pressure; classified as high or low.

Low Explosives

Substances like black powder and smokeless powder that deflagrate (burn rapidly).

Deflagration

The rapid burning of a substance, characteristic of low explosives.

High Explosives

Substances like TNT or RDX that detonate and create shock waves.

Detonation

A rapid explosion producing a supersonic shock wave.

Primary Explosives

Highly sensitive materials used to initiate secondary explosives (e.g., blasting caps).

Secondary Explosives

More stable explosives that require a primary explosive to detonate (e.g., TNT, RDX).

TATP (Triacetone Triperoxide)

A volatile homemade explosive made from acetone and peroxide.

RDX

A powerful military explosive commonly found in plastic explosives like C-4.

Ion Mobility Spectrometer (IMS)

A tool for detecting explosive residues by analyzing ion movement through an electric field.

Crater

A depression formed at the explosion's point of origin; evidence is collected from inside.

Color Spot Tests

Chemical tests for detecting explosive residues by color change.

Thin-Layer Chromatography (TLC)

A technique for separating components of explosives or residues.

Gas Chromatography/Mass Spectrometry (GC/MS)

A confirmatory test that identifies substances by mass fragmentation patterns.

IR Spectrophotometry

A technique for confirming explosives by identifying molecular fingerprints.

Serology

A branch of science dealing with the measurement and characterization of antibodies, antigens, and other immunological substances in blood.

Antigen

A substance (usually a protein) that stimulates the body to produce antibodies.

Antibody

A protein in blood serum that destroys or inactivates specific antigens.

Presumptive Testing

A screening test used when a fluid is suspected to be blood or semen, based on a visible color change.

Confirmatory Testing

A test performed after a presumptive test to confirm the presence of a specific body fluid.

Kastle-Meyer Test

Presumptive test for blood that turns pink in the presence of hemoglobin.

Acid Phosphatase Test

Presumptive test for semen that turns purple when enzyme activity is detected.

Takayama Crystal Test

Confirmatory test for blood that forms crystals when blood is present.

RSID (Rapid Stain Identification)

Strip tests that identify specific body fluids from forensic evidence.

Red Blood Cells (Erythrocytes)

Carry oxygen; contain antigens; lack a nucleus.

White Blood Cells (Leukocytes)

Part of the immune system; have a nucleus.

Platelets (Thrombocytes)

Help with blood clotting.

Plasma

Fluid portion of blood (55%), mostly water with antibodies, vitamins, and proteins.

Rh Factor

A protein that determines whether a blood type is positive (+) or negative (-).

False Positive

A test result that incorrectly indicates the presence of a substance.

False Negative

A test result that incorrectly shows no presence of a substance when it is there.

Luminol Test

A sensitive presumptive test for detecting trace amounts of blood via chemiluminescence.

Seminal Fluid

Fluid containing sperm and other components like sugars, proteins, and ions.

Oligospermia

Medical condition causing low sperm count.

Aspermia

Medical condition resulting in no sperm production.

Vasectomy

A surgical procedure preventing sperm production.

p30 (Prostate-Specific Antigen)

Glycoprotein used to confirm semen presence; produced by prostate gland.

Christmas Tree Staining

A technique using red and green stains to identify sperm cells microscopically.

Amylase

An enzyme found in saliva and pancreas that digests starch.

Phadebas Amylase Saliva Test

Saliva test using a tablet that turns blue when amylase breaks down starch.

DNA (Deoxyribonucleic Acid)

A chain of chemical building blocks (G, A, T, C) that carries genetic information.

Short Tandem Repeats (STRs)

Non-coding DNA sequences made of repeating units; used in DNA profiling.

Epithelial Cells

Skin cells that can leave DNA traces even without visible stains.

Contamination

The unintentional addition of external material or DNA to a crime scene or evidence.

Direct Transfer

DNA or cells transferred directly by touching.

Indirect Transfer

DNA transferred without direct contact (e.g., via another object or person).

Aerosol Transfer

DNA transferred through saliva by sneezing, coughing, or talking.