Crime Scene Investigation and Forensic Science Midterm Review

Flashcards based on the Crime Scene Investigation and Forensic Science lecture review guide.

First Responder

The initial law enforcement officer or official arriving at a crime scene, responsible for securing the scene, rendering aid, and preserving physical evidence.

Hot Search

A search conducted immediately after a crime occurs, focused on locating a suspect believed to still be on or near the scene.

Cold Search

A search conducted after time has elapsed and there is no immediate belief that the suspect is still near the crime scene.

Chain of Custody

The documented, unbroken chronological record tracking the ownership, collection, transfer, analysis, and disposition of physical evidence.

Wet Evidence Packaging

Moist or biological evidence that must be air-dried prior to packaging in breathable paper containers to prevent mold and bacterial degradation.

Trace Evidence Packaging

Small, physical evidence packaged using paper folds (druggist folds), small pill boxes, or paper envelopes to prevent loss or contamination.

Fire Residues Packaging

Arson or fire debris evidence required to be packaged in clean, airtight containers, such as metal paint cans or glass jars, to prevent volatile accelerants from evaporating.

Sieving

A separation technique that separates coarse mixtures based on particle size by passing the material through porous meshes or screens.

Chromatography

A suite of analytical techniques used to separate complex mixtures into individual chemical components based on differential distribution between a mobile phase and a stationary phase.

Stationary Phase

The non-moving, fixed material (solid or liquid supported on a solid) through which the mobile phase moves during chromatography.

Mobile Phase

The liquid or gas fluid that carries the sample mixture through the stationary phase in chromatography.

Mass Spectrometer

An analytical instrument that measures the mass-to-charge ratio of charged particles to identify and quantify chemical compounds in forensic evidence.

Gel Electrophoresis

A laboratory method used to separate biological macromolecules (such as DNA, RNA, or proteins) according to size and charge using an electric field through a gel matrix.

Electromagnetic Radiation

Form of energy propagated through space as oscillating electric and magnetic fields traveling at the speed of light.

Electromagnetic Spectrum

The complete continuum of all forms of electromagnetic radiation ordered by wavelength or frequency.

Wavelength and Energy Relationship

An inverse relationship where as the wavelength of electromagnetic radiation increases, its energy decreases (E = \frac{hc}{\frac{}{\raisebox{0ex}{\text{wavelength}}}}).

Dual Nature of Light

The physical principle stating that light exhibits properties of both continuous waves and discrete particles (photons).

Visible Light Range

The narrow region of the electromagnetic spectrum perceptible to the human eye, spanning wavelengths between approximately $400\text{ nm}$ and $700\text{ nm}$.

Metamerism

The phenomenon in which two color samples match under one specific light source or lighting condition but appear distinctly different under another.

UV-Vis Spectrophotometry

An analytical technique measuring the absorbance or transmittance of ultraviolet ($100\text{ nm} - 400\text{ nm}$) and visible ($400\text{ nm} - 700\text{ nm}$) light by a sample to quantify chemical species.

Infrared Spectrophotometry

An analytical technique measuring molecular absorption of infrared radiation, providing structural information and functional group identification based on molecular vibrations.

Simple Magnifier

A optical device consisting of a single convex lens used to magnify objects by refracting light.

Compound Microscope

A magnification system using two main lens groups—the objective lens near the object and the ocular lens near the eye—to achieve higher optical magnification via light refraction.

Individual Evidence

Evidence that can be attributed to a single, unique source with an extremely high degree of certainty (e.g., DNA, fingerprints).

Class Evidence

Evidence that can only be associated with a group or category of items sharing common characteristics (e.g., mass-produced fiber, brand-new shoes).

Probative Value

The degree to which evidence is useful or significant in proving or disproving a material fact in a legal proceeding.

Trier of Fact

The judge or jury in a legal trial responsible for evaluating evidence to make factual determinations and reach a verdict.

Expert Witness

An individual possessing specialized skill, training, or knowledge permitted by the court to offer opinion testimony on technical or scientific matters.

Frye Standard vs Daubert Standard

Legal thresholds for scientific evidence admissibility: Frye requires general acceptance in the scientific community, whereas Daubert positions the judge as a gatekeeper assessing scientific validity, peer review, error rates, and testing methods.

Real Evidence vs Demonstrative Evidence

Real evidence consists of tangible physical objects directly involved in the crime, whereas demonstrative evidence includes diagrams, photos, or models created to explain facts or illustrate testimony to the court.

Controls in Testing

Known positive and negative reference samples analyzed alongside unknown evidence to ensure test reagents and procedures operate correctly and accurately.

Privileges in Court

Legal rights that protect specific confidential relationships (such as attorney-client or doctor-patient) from forced disclosure during legal proceedings.