Forensic Science I Midterm Review

Comprehensive vocabulary flashcards covering foundational legal principles, crime scene procedures, ballistics, trace and impression evidence, bloodstain dynamics, wound pathology, constitutional search doctrine, fingerprint identification, and specialized case analyses from Forensic Science I.

Forensic Science

The application of science and technology to questions arising in criminal or civil legal matters.

Due Process

The requirement that the government follow constitutionally fair procedures before depriving an individual of life, liberty, or property, guaranteed by the Fifth and Fourteenth Amendments.

Presumption of Innocence

The foundational principle that a defendant begins a criminal trial presumed innocent and is not required to prove their own innocence.

Burden of Proof

The prosecution's legal obligation to prove every required statutory element of a charged crime beyond a reasonable doubt.

Chain of Custody

The documented, unbroken record of collection, possession, transfer, storage, and handling of an exhibit, demonstrating that it is the same item and remains in substantially unchanged condition.

Admissibility

The preliminary legal determination, generally made by a judge, regarding whether evidence may be introduced and presented in court.

Weight (of Evidence)

The degree of persuasiveness and credibility assigned to admitted evidence, typically evaluated by the trier of fact (often a jury).

Direct Evidence

Evidence that establishes a fact directly without requiring an intervening inference, such as an eyewitness account of seeing an event occur.

Circumstantial Evidence

Evidence that relies on an inference to connect it to a conclusion of fact, such as footwear impressions, motive, fingerprint matches, or DNA.

Collateral Evidence

Background material that informs investigators about a subject's general interests or behavior without directly tying them to the crime.

Known/Reference Sample

Physical material gathered from an established, verified source used as a standard for scientific comparison against questioned evidence.

Questioned Sample

Evidence collected from a crime scene whose source, origin, or exact identity is unknown and subject to investigation.

Ballistics

The scientific study of projectiles, their mechanics, and their flight behavior.

Internal Ballistics

The branch of ballistics that studies mechanical and chemical events occurring inside a firearm during discharge.

External Ballistics

The branch of ballistics that studies the flight and aerodynamic behavior of a projectile after leaving the barrel and before striking a target.

Terminal Ballistics

The branch of ballistics examining projectile behavior, wound dynamics, and physical effects upon impact with a target.

Caliber

The nominal diameter of a firearm bore or projectile, commonly designated in hundredths of an inch or in millimeters.

Rifling

Spiral lands and grooves machined into the interior surface of a barrel that impart rotational spin to stabilize the projectile.

Lands

The raised structural surfaces located between the grooves inside a rifled firearm barrel.

Grooves

The cut or recessed helical channels inside the bore of a rifled firearm barrel.

Striations

Microscopic, parallel scratch markings etched onto the surface of a bullet as it travels along the rifled barrel.

Comparison Microscope

An optical instrument with two objective stages joined by an optical bridge, enabling side-by-side simultaneous comparison of two specimens such as bullets or cartridge cases.

IBIS

Integrated Ballistic Identification System; an automated system that acquires and compares digital images of ballistic evidence to generate candidate associations.

NIBIN

National Integrated Ballistic Information Network; a U.S. ballistic imaging network that connects shooting incidents by comparing digital images of recovered fired cartridge cases.

Locard's Exchange Principle

The foundational principle that every physical contact leaves a trace, resulting in a reciprocal transfer of material between people, objects, and environments.

Randomly Acquired Characteristics (RACs)

Individualizing scratches, cuts, tears, or wear marks randomly acquired by an object through use and environmental exposure.

Physical Fit

The mechanical, jigsaw-like realignment of two or more fractured fragments, demonstrating that they originated from the exact same unbroken object.

Passive Drops

Bloodstains created exclusively through the force of gravity acting on liquid blood without an active propulsion or assault force.

Swipe

A bloodstain pattern produced by the transfer of blood onto an unstained surface when a bloody object moves across it.

Wipe

A bloodstain pattern created when an object moves through a preexisting, wet bloodstain, altering or displacing its appearance.

Impact Spatter

A pattern of dispersed blood droplets created when an external force or energy strikes exposed liquid blood.

Cast-off

A bloodstain pattern generated when blood is released from a moving blood-bearing object, such as a swung weapon, due to centrifugal force and acceleration.

Arterial Gush/Spurt

A bloodstain pattern formed by the pressurized release of blood from a breached artery, typically presenting as undulating, pulsatile waves.

Void (Shadow)

An unspattered gap within an otherwise continuous bloodstain pattern, indicating that an intervening person or object blocked deposition and was subsequently removed.

Luminol

A presumptive chemical reagent that produces chemiluminescence when catalyzed by the heme-associated iron in hemoglobin, used to reveal latent blood traces.

4R Rule

The principle of glass fracture mechanics stating that Ridges on Radial fractures form Right angles on the Rear side of the glass (opposite the side of impact).

Primer Gunshot Residue (PGSR)

Residue particles characterized by a traditional elemental combination of lead, barium, and antimony, often exhibiting a molten or spherical shape measuring approximately $1\text{ to }5\,\mu\text{m}$.

Abrasion

A superficial mechanical scraping injury confined to the outer layers of the skin.

Contusion

A bruise caused by blunt mechanical trauma that ruptures small subsurface blood vessels while leaving the overlying skin intact.

Laceration

A mechanical tear or splitting of soft tissue produced by blunt crushing or shearing force, typically displaying irregular wound margins and internal tissue bridging.

Tissue Bridging

Intact strands of nerves, connective tissue, or blood vessels spanning the margins of a blunt-force laceration, distinguishing it from an incised wound.

Incised Wound

A clean-edged sharp-force cut or slash that is typically longer on the skin's surface than it is deep.

Stab Wound

A sharp-force penetrating puncture wound that is deeper along its internal track than it is wide on the cutaneous surface.

Chop Wound

A deep sharp-force injury delivered with substantial kinetic energy by a heavy, bladed tool (such as an axe), frequently resulting in underlying bone cuts and fractures.

Penetrating Gunshot Wound

A gunshot wound that has an entrance opening into an anatomical region but lacks an exit, causing the projectile to be retained in the body.

Perforating Gunshot Wound

A gunshot wound featuring both an entrance and an exit, indicating the projectile passed entirely through the described anatomical region or structure.

Dynamic Loading

Blunt-force trauma resulting from rapid, instantaneous impacts, such as punches, falls, collisions, or strikes from blunt objects.

Static Loading

Blunt-force trauma resulting from sustained, continuous crushing compression applied to the body over a prolonged duration.

Permanent Cavity

The direct void and tissue tract crushed, cut, and permanently destroyed by the physical passage of a projectile.

Temporary Cavity

The temporary displacement and lateral stretching of soft tissues surrounding a bullet's path, caused by transferred kinetic energy.

Probable Cause

A practical, fair probability, evaluated under the totality of circumstances, that contraband or evidence of a crime will be found in a particular location.

Curtilage

The land and buildings immediately surrounding and intimately associated with domestic home life, receiving significant Fourth Amendment search protections.

Exclusionary Rule

The judicial remedy dictating that physical or testimonial evidence seized in violation of a defendant's constitutional rights cannot be used at trial.

Fruit of the Poisonous Tree

A legal doctrine specifying that secondary evidence derived indirectly from an initial unlawful search or constitutional violation must also be suppressed.

Katz Test

The two-prong legal test evaluating whether an individual exhibited an actual subjective expectation of privacy, and whether that expectation is one society recognizes as objectively reasonable.

Bertillon System

An early anthropometric identification system that cataloged individuals through standardized physical body measurements, anatomical notations, and photographs.

Patent Print

A clearly visible friction ridge impression transferred onto a surface by an intermediate foreign medium such as blood, ink, paint, or dirt.

Plastic Print

A three-dimensional friction ridge impression molded into a pliable, yielding substance such as wax, fresh paint, clay, or putty.

Latent Print

A hidden or invisible friction ridge impression formed by the transfer of natural bodily secretions (sweat and sebum) that requires physical or chemical processing to be seen.

Loop

The most common friction ridge pattern (accounting for approximately $65\%$ of prints), defined by ridges entering from one side, curving back, and exiting on the same side.

Minutiae

Individualizing localized friction ridge characteristics (also called Galton details), such as ridge endings, bifurcations, and dots, used to compare and identify fingerprints.

Cyanoacrylate Fuming

A latent print visualization method in which heated superglue vapors polymerize selectively along friction ridge residues on nonporous surfaces.

Ninhydrin

A chemical reagent that develops latent friction ridge prints on porous surfaces, such as paper, by reacting with trace amino acids to produce a visible purple compound.

Investigative Genetic Genealogy (IGG)

An investigative workflow that analyzes single-nucleotide polymorphism DNA profiles against commercial databases to find genetic relatives and construct family trees to identify unknown remains or suspects.

McHoul Standard

The Massachusetts legal standard for lack of criminal responsibility, asking whether, due to a mental disease or defect, the defendant lacked substantial capacity either to appreciate the wrongfulness of their conduct or to conform their conduct to the requirements of law.