Forensic Science Midterm Review

Comprehensive vocabulary flashcards covering key forensic science concepts, investigation workflows, trace evidence, impression recovery methods, and biological evidence analysis.

The "CSI effect"

A phenomenon where jurors demonstrate elevated expectations for scientific evidence, though research found little evidence that watching crime dramas alone drives wrongful acquittals.

Forensic Biology

The forensic discipline dedicated to analyzing DNA and bodily fluid evidence.

Forensic Toxicology

The forensic discipline that identifies and analyzes drugs and poisons within the human body.

Forensic Chemistry

The forensic discipline focused on testing and identifying unknown chemical substances.

Questioned Documents Examination

The forensic discipline that investigates handwriting, forgery, ink, and paper authenticity.

Firearms and Tool Mark Examination

The forensic discipline dedicated to matching weapons and tools to the distinct marks left behind at a scene.

Forensic Entomology

The study of insect activity on a decomposing body to estimate the time since death.

Forensic Anthropology

The application of physical anthropology for the identification and examination of human skeletal remains.

Forensic Odontology

The examination and comparison of bite marks and dental records for forensic identification.

Forensic Botany

The analysis of plant evidence used to determine the time and geographical location of a crime.

Bloodstain Pattern Analysis

The study of the shape, size, location, and distribution of bloodstains to provide information about the event(s) that produced them.

Fingerprint Minutiae

The specific, detailed ridge characteristics (including ridge endings, bifurcations, lakes, independent ridges, points/islands, spurs, and crossovers) that are unique to an individual and generated by random developmental processes.

Fingerprint General Pattern Types

The three broad friction ridge classifications (loop, whorl, arch) that exhibit a measurable familial tendency influenced by both parents.

Epidermis

The thin surface layer of the skin, anchored atop the dermis by a double row of dermal papillae informally referred to as "little skin pegs."

Dermis

The thick foundation layer of the skin that provides the mechanical and structural base upon which upper layers rest.

Hypodermis (Subcutaneous Layer)

The deepest skin layer beneath the dermis composed primarily of adipose (fat) and connective tissue; it anchors skin to bone and muscle, absorbs mechanical forces, and provides cushioning, insulation, and energy storage.

Primary Crime Scene

The actual physical location where the criminal act took place.

Secondary Crime Scene

Any location connected to the crime other than where the crime occurred, such as a vehicle, body disposal site, or suspect's residence.

Crime Scene Investigation Workflow

The systematic eight-step procedural framework: 1. Recognition & Safety, 2. Secure & Protect, 3. Walkthrough & Plan, 4. Photograph, 5. Sketch & Notes, 6. Search, 7. Collect & Package, and 8. Chain of Custody.

Initial Walkthrough (Step 3)

A preliminary, non-intrusive survey conducted by the lead investigator—observing only without touching—to formulate a documentation strategy and establish a baseline mental map.

Triangulation (Crime Scene Sketching)

A measurement method used on rough crime scene sketches that records the exact distance of an evidence item from at least two fixed reference points.

Chain of Custody

A continuous, documented record detailing every person who has possessed, transferred, or analyzed a piece of evidence from collection to the courtroom.

Kastle-Meyer Test

A presumptive chemical test used to detect the presence of blood in forensic laboratories, though it cannot differentiate between human and non-human blood.

Locard's Exchange Principle

The core tenet of forensic science stating that "Every Contact Leaves a Trace."

Trace Evidence

Small quantities of transferred material—such as textile fibers, paint flakes, glass fragments, soil, and gunshot residue—recovered from a scene and interpreted in context.

Radial and Concentric Fractures

Fracture formations produced in glass upon projectile impact; radial fractures project outward like spokes from the impact point, while concentric fractures form circular crack lines around it.

Two-Dimensional (2D) Impression

A print that possesses length and width but lacks significant depth, such as a dusty shoe print on tile or a bloody print on a countertop.

Three-Dimensional (3D) Impression

An impression featuring length, width, and depth formed when footwear physically displaces a substrate downward, such as in mud, soil, or snow.

Keystone Effect

An optical distortion occurring when an impression is photographed at an angle rather than perpendicular ($90^\circ$), causing parallel features to converge and rendering size calculations inaccurate.

Gel Lifter

A soft, tacky rubber or gel-surfaced sheet pressed onto an impression to lift delicate dust or powder without the streaking risk associated with adhesive tape.

Electrostatic Dust Lifter

A specialized device that utilizes high-voltage static electricity to transfer fragile dust impressions onto a charged film without adhesive or physical pressure.

Dental Stone Casting (The Knaap Method)

A recovery technique where a dental stone mixture is poured directly into a 3D impression to cure into a rigid, durable replica suitable for transport and courtroom analysis.

Sulfur Casting

A specialized casting technique developed explicitly for capturing delicate 3D footwear impressions in very cold snow.

RFLP Analysis

Restriction Fragment Length Polymorphism; a DNA profiling method utilizing Variable Number of Tandem Repeats (VNTRs) to produce unique banding patterns that distinguish individuals.

The Golden Rule of Blood Chemistry

The sequential testing protocol arranged from least to most destructive: 1. Photography, 2. Visual (ambient light), 3. Visual (white light, ALS, laser), 4. Blood locators, and 5. Blood enhancers.

Algor Mortis

The postmortem cooling of the body, influenced by ambient temperature, body size, clothing, air circulation, water exposure, fever, and surface contact.

Livor Mortis

The postmortem pooling and settling of blood due to gravity, which produces skin discoloration patterns indicative of body position and potential postmortem movement.

Rigor Mortis

The postmortem muscular stiffening whose development, intensity, and resolution are governed by environmental temperature, metabolic activity, body habitus, and disease.

Spatter Bloodstains

Bloodstains formed when external force is applied to liquid blood, propelling airborne drops away from the source.

Gravity Bloodstain Patterns

Blood patterns produced exclusively under the influence of gravitational pull, including drip stains, drip trails, splash patterns, flows, pools, and saturation stains.

Cast-Off Pattern

A spatter bloodstain pattern created by blood drops swinging free and detaching from a moving weapon or object in motion.

Expiration Pattern

A spatter pattern produced when internal pressure and airflow expel blood from the mouth, nose, or an open airway wound.