Forensic Science: Fingerprints, Biometrics, Microscopes, and Firearms Analysis

anthropometry

The measurement of the human body.

arch

A common fingerprint pattern characterized by ridges that enter from one side and exit the other.

digital imaging

The creation of a digital representation of a physical object.

fluoresce

To emit light as a result of absorbing light or other electromagnetic radiation.

iodine fuming

A method used to visualize latent fingerprints using iodine vapor.

latent fingerprint

A fingerprint that is not visible to the naked eye.

livescan

A digital method of capturing fingerprints.

loop

A fingerprint pattern where ridges enter from one side, loop around, and exit the same side.

ninhydrin

A chemical used to develop latent fingerprints by reacting with amino acids.

physical developer

A method used to visualize latent fingerprints on porous surfaces.

pixil

A term related to digital imaging, referring to the smallest unit of a digital image.

plastic print

A three-dimensional impression of a fingerprint left in a soft material.

ridge characteristics (minutiae)

Unique features of a fingerprint such as bifurcations and ridge endings.

sublimation

The process of a substance transitioning from solid to gas without becoming liquid.

superglue fuming

A technique used to visualize fingerprints by fuming cyanoacrylate.

visible fingerprints

Fingerprints that are visible without any enhancement.

whorl

A fingerprint pattern characterized by ridges that form circular or spiral patterns.

biometrics

The measurement and statistical analysis of people's unique physical and behavioral characteristics.

iris

The colored part of the eye that controls the size of the pupil.

retina

The light-sensitive layer at the back of the eye.

Eigenfaces

A set of eigenvectors used in the computer vision problem of human face recognition.

depth of focus

The range within which the image remains in focus.

field of view

The extent of the observable world that can be seen at any given moment.

virtual image

An image formed by rays that appear to diverge from a point.

real image

An image formed by the actual convergence of light rays.

magnification

The process of enlarging the appearance of an object.

working distance

The distance between the objective lens and the specimen.

compound microscope

A microscope that uses multiple lenses to magnify an object.

stereo microscope

A microscope that provides a three-dimensional view of a specimen.

microspectrophotometer

An instrument that measures the spectrum of light absorbed by a microscopic sample.

comparison microscope

A microscope that allows side-by-side comparison of two specimens.

scanning electron microscope

A type of electron microscope that produces images of a sample by scanning it with a focused beam of electrons.

forensic palynology

The study of pollen and spores in forensic investigations.

pollen

The male gametophyte of seed plants, responsible for fertilization.

spores

Reproductive units capable of developing into a new individual without fusion.

plane-polarized light

Light that vibrates in a single plane.

bore

The interior diameter of a firearm barrel.

breechblock

The part of a firearm that closes the rear of the chamber.

caliber

The diameter of a firearm's bore, usually measured in millimeters or inches.

choke

A constriction at the end of a shotgun barrel that affects the spread of the shot.

distance determination

The process of calculating the distance from which a shot was fired.

firearms identification

The forensic science of identifying firearms and ammunition.

gauge

A measurement of the diameter of a shotgun barrel.

Greiss test

A chemical test used to detect the presence of gunshot residue.

grooves

The spiral cuts inside a firearm barrel that impart spin to a bullet.

lands

The raised portions between the grooves in a rifled barrel.

rifling

The helical grooves cut into the bore of a firearm barrel.

element

A pure substance that cannot be broken down into simpler substances.

amorphous solid

A solid that lacks a defined crystalline structure.

atom

The smallest unit of an element, consisting of protons, neutrons, and electrons.

birefringence

The optical property of a material that has a different refractive index in different directions.

Celsius scale

A temperature scale where 0 degrees is the freezing point of water.

chemical property

A characteristic of a substance that can be observed during a chemical reaction.

compound

A substance formed when two or more elements chemically bond together.

concentric fracture

A type of fracture that occurs in a circular pattern around a point of impact.

crystalline solid

A solid material whose constituents are arranged in a highly ordered structure.

density

The mass per unit volume of a substance.

dispersion

The process of separating light into its component colors.

electromagnetic spectrum

The range of all types of electromagnetic radiation.

Fahrenheit scale

A temperature scale where 32 degrees is the freezing point of water.

gas

A state of matter with no fixed shape or volume.

intensive property

A property that does not depend on the amount of substance present.

laminated glass

Glass that is made by sandwiching a layer of plastic between two layers of glass.

laser

A device that emits light through a process of optical amplification.

liquid

A state of matter that has a definite volume but no definite shape.

mass

The amount of matter in an object.

matter

Anything that has mass and occupies space.

molecule

Two or more atoms bonded together.

periodic table

A tabular arrangement of the chemical elements, organized by atomic number.

photon

A particle representing a quantum of light.

radial fracture

A type of fracture that radiates outward from a point of impact.

refraction

The bending of light as it passes from one medium to another.

refractive index

A measure of how much light bends when entering a material.

solid

A state of matter with a definite shape and volume.

states of matter

The distinct forms that different phases of matter take on.

visible light

The portion of the electromagnetic spectrum that is visible to the human eye.

wavelength

The distance between successive crests of a wave.

weight

The force exerted by gravity on an object.

frequency

The number of occurrences of a repeating event per unit of time.

Comparison microscopes

Used to compare hair or fibers and examine rifling marks on bullets.

Stereomicroscopes

Used to locate trace evidence in debris, garments, weapons, or tools.

Polarizing microscopes

Designed to characterize plane-polarized light and used to characterize minerals present in soil or birefringent synthetic fibers.

Scanning Electron Microscopes

Used to analyze pollen, spores, fibers, and gun powder residue.

Anemophilous pollen dispersion

Pollen dispersion through wind.

Entomophilous pollen dispersion

Pollen dispersion through insects.

Rifling techniques

Includes broach cutting, button process, and mandrel rifling.

Class characteristics of bullets

Includes number of lands and grooves, direction of twist, and degree of rotation.

Individual characteristics of bullets

Includes striation markings.

Comparison microscope use

Used to compare bullets and cartridge cases by matching lands and grooves and striation markings.

Firing pin and breechblock impression

Compared on the cartridge cases.

NIBIN database

A database for ballistic evidence.

Powder-residue patterns

Used to determine how far a weapon was fired from a target.

Laboratory tests for fired weapons

Includes Greiss test, SEM testing, and elemental analysis by x-ray analyzer.

Shoeprints characteristics

Includes class characteristics (shoe brand tread marks) and individual characteristics (damage, wear, and grit).

Electrostatic lifting process

A method used to lift latent prints from surfaces.

Types of matter

Includes elements and compounds.

Phases of matter

Common phases include solid, liquid, gas, and transitions between these phases.

Nature of light

Light behaves as both a wave and a particle.

Types of glass

Includes soda lime glass, borosilicate glass, tempered glass, and laminated glass.

Forensic methods for comparing glass fragments

Includes density using flotation and refractive index using immersion in silica oil.