Forensic Science Final

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175 terms

Physical Evidence

Any object that can establish that a crime has or has not been committed, or link an individual to a crime.

Chain of Custody

A list of all people who came into possesion of an item of evidence.

Standard Reference Sample

Physical evidence whose origin is known, such as blood or hair from a suspect.

Substrate Control

Uncontaminated surface material close to an area where physical evidence has been posited.

Buccal Swab

A swab of the innter portion of the cheek; DNA sample

Identification

The process of determining a substances physical or chemical identity ex: drug analysis

Comparison

The process of ascertaining whether two or more objects have a common origin.

Individual Characteristics

Properties of evidence that can be attributed to a common source with an extremely high degree of certainty.

Class Characteristics

Properties of evidence that can be associated only with a group, not one thing.

Product Rule

Multiplying together the frequencies of independently occurring genetic markers.

Forensic Pathologist

An individual who investigates sudden, unnatural, unexplained, or violent deaths.

Autopsy

The medical dissection of and examination of a body to determine death.

Rigor Mortis

Stiffening of body after death.

Livor Mortis

Settling of blood after death, the blood is most abundant in areas closest to the ground due to gravitational pull.

Physical Property

The behavior of a substance without altering compostion, how it appears.

Chemical Property

The behaviorof a substance when it reacts orcombines with another substance. Chemical reactions

Intensive Property

A property that is not dependent on the size of an object.

Refraction

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

Refractive Index

The ratio of the speed of light in a vacuum to its speed in a given substance.

Crystalline Solid

A solid in which the constituent atoms have a regular arrangement.

Amorphous Solid

Atoms are arranged in random disordered positions.

Laminated Glass

Two sheets of ordinary glass bonded together with a plastic film.

Tempered Glass

Glass strengthened by introducing stress through rapid cooling and heating.

Becke line

Refractive index unit.

Radial Fracture

A crack in the glass that extends outward like a spoke of a wheel from where it was struck.

Concentric Fracture

A crack in the glass that forms a rough ircle around the point of impact.

Matter

All things of substance, matter is composed of atoms and or molecules.

Element

Cannot be broken down, it is the fundamental unit of compounds and molecules.

Periodic Table

A table of elements arranged in a systematic fashion by atomic mass.

Compound

A pure substance composed of two or more elements

Physical State

A condition or stage in the form of matter: solid, liquid, gas.

Sublimation

A physical change from the solid state directly into a gaseous state.

Spectrophotometry

An analytical method for indentifying a substance by its selective absorption.

Chromatogragphy

Any of several analytical techniques for sparating organic mixtures. There is a stationary and a mobile phase.

Pyrolysis

The decomposition of organic matter by heat.

Fluoresce

To emit visible light when exposed to light of a shorter wavelength ultraviolet light.

Electrophoresis

A technique for separating molecules through migration on a support medium while under the influence of an electrical potential.

Visible light

Colored light ranging from red to violet in the electromagnetic spectrum.

Wavelength

The distance between crests of adjacent waves.

Frequency

The number of waves that pass a given point per second. Shorter wavelength means a higher frequency.

Electromagnetic Spectrum

The entire range of radiation energy from the most energetic to the least energetic. The rainbow is the magnetic spectrum.

X-Ray

A high energy short wavelength form of electromagnetic radiation.

Laser

An acronym for light amplification by stimulated emission of radiation. The light is a beam of unison pulse.

Photon

A small packet of electromagnetic radiation energy. Each photon contains a unit of energy equal to the product of Planks Constant.

Monochromator

A device for isolating individual wavelengths for frequencies of light.

Monochromatic Light

light having a single wavelength or frequency.

Ultraviolet

Invisible long frequencies of light beyond violet in the visible spectrum.

Infrared

invisible short frequencies of light before red in the visible spectrum.

Ion

An atom or molecule bearing a positive or negative charge.

Virtual Image

An image that cannot be seen directly. It can be seen only by a viewer looking through a lens.

Real Image

An image formed by the actual convergence of light rays ona screen.

Objective Lens

The lower lens of a microscopre which is positioned directly over speciments.

Eyepiece Lens

The lens of a microscope into which the viewer looks; same as an occular lense.

Transmitted Illumination

light that passes up from the condenser and through the speciment.

Vertical/Reflected Illumination

Illumination of a specimen from above; in microscopy it is used to examen opaque specimens.

Condenser

The lens system under the microscope that focuses light onto the specimen.

Monocular

Describes a microscope with only one eyepiece, lens.

Parfocal

Describes a microscope such that when an image is focused with one objective in position the other objective can be rotated into place.

Binocular

Describes a microscope with two eyepieces.

Field of View

The area of the specimen that can be seen after it is magnified.

Depth of Focus

The thickness of a specimen that is entirely in focus under a microscope.

Plane Polarized Light

Light confined to a single plane of vibration.

Polarizer

A device that permits the passage of light waves vibrating in only one plane.

Microspectrophotometer

An instrument that links a microscope to a spectrophotometer.

Psychological Dependence

Conditional use of a drug caused by underlying emotional needs.

Physical Dependence

Physiological need for a drug that has been brought about by its regular use. Dependence is characterized by withdrawls sickness when administration of the drug is abruptly stopped.

Hallucinogen

A substance that induces changed in mood, attitude, thought process, and perceptions.

Depressant

A substance that depresses the functions of the central nervous system, depressants calm irritability and anxiety and may induce sleep.

Stimulant

A substance taken to increase alertness or activity.

Anabolic Steroids

Steroids that promote muscle growth.

Screening Test

A test that is nonspecific and preliminary in nature.

Confirmation

A single test that specifically identifies a substance in the body.

Microcrystalline Test

Tests to identify specific substances by the color and morphology of the crystals formed when the substance is mixed with specific reagent.

Absorption

Passage of alcohol across the wall of the stomach and stomach and small intestine into the bloodstream.

Oxidation

The combination of oxygen with other substances to produce new products.

Excretion

Elimination of alcohol from the body in an unchanged state; alcohol is normally excreted in breath and urine.

Artery

A blood vessel that carries blood away from the heart.

Vein

A blood vessel that transports blood towards the heart.

Capillary

A tiny blood vessel across whoce walls exchange of materials between the blood and the tissues take place; recieves blood from arteries.

Alveoli

Small sacs in the lungs through whose walls air and other vapors are exchanged between breath and the blood.

Fuel Cell Detector

A detector in which chemical reactions produce eletricity.

Anticoagulant

A substance that prevent coagulation or clotthing of the blood.

Preservative

A substance that stops the growth of microorganisms in blood.

Metabolize

To transform a chemical in the body to another chemical to facilitate its elimination from the body.

Acid

A compound capable of donating a hydrogen ion to another compound.

Base

A compound capable of accepting a hydrogen ion

pH Scal

A scale used to express the basicity or acidity of a substance; pH neutral 7, 1-7 acid. 7 + Base.

Chromosome

A rod like structure in the cell nucleus, along which the genes are located, composed of DNA.

Polymer

A substance composed of a large number of atoms; these atoms are usually arranged in repeating monomers.

Nucleotide

The unit of DNA consisting of one of four bases Adenine, Guanine, Cytosinge, Thymine, they are phosphate sugar groups.

Complementary Base Pairing

The DNA helix strands have matching pairs of phosphate sugar groups. A+T C+G

Proteins

polymers of amino acids that play basic roles in the structures and functions of living things.

Amino acids

The building blocks of proteins; there are twenty common amino acids.

Human Genome

The total DNA content found withi the nucleus of a human cell; three billion base pairs.

Replication

The synthesis of new DNA from existing DNA.

Polymerase Chain Reaction

A technique for replication or copying a portion of DNA strands outside a living cell.

Primer

A short strand of DNA used to target a regio of DNA for replication by PCR.

Hybridization

The process of joining two complementary strands of DNA to form a double stranded molecule.

Tandem Repeat

A region of a chromosome that contains multiple copies of a core DNA sequence that are arranged in repeating fashion.

Restriction Fragment Length Polymorphism

Different fragment length of base pairs that result from cutting a DNA molecule with restriction enzymes.

Short Tandem Repeat

A region of a DNA molecule that contains short segments consisting of three to seven repeating base pairs.

Multiplexing

A technique that simultaneously detects more than one DNA marker in a single analysis

Amelogenin Gene

A genetic locus useful for determing gender.

Y-Strs

Short tandem repeats located on the human y chromosome.

Mitochondria

Small structures loated outside the nucleus of a cell, powerhouse.

Sequencing

A procedure used to determine the order of the base pairs that constitute DNA.

Low Copy Number

Fewer than eighteen DNA bearing cells

Picogram

One trillionth of a gram

Epithelial cells

The outher layer of skin cells, these DNA bearing cells often fall off of or are rubbed off onto objects retrieved from crime scenes.

Touch DNA

DNA from skin cells transferred onto the surface of an object by simple contact.

Crime Scene Reconstruction

Method used to support a likely sequence of events at a crime scene by observation ect.

Satellite Splatter

Small droplets of blood that are distributed around the perimeter of a drop or drops of blood and were produced as a result of the blood impacting the target surface.

Angle of Impact

The acute angle formed between the path of a blood drop and the surface that it contacts.

Impact Spatter

A bloodstain pattern produced when an object makes forceful contact with a source of blood, projecting drops of blood outward from the source.

Forward Spatter

Blood that travels away from the source in the same direction as the force that caused it.

Back Spatter

blood directed back toward the source of the force that caused the spatter.

Low Velocity Spatter

An impact spatter pattern caused by a force traveling at five feet per second or less and producing drops with diameters greater than 3 mm.

Medium Velocity Spatter

An impact spatter pattern created by a force traveling at five to twenty five feet per second.

High Velocity Spatter

An impact spatter pattern created by a forc traveling at 100 feet per second or faster and producing drops less than 1 mm.

Area of Convergence

The area on a two dimensional plane where lines traced through the long axis of several individual bloodstains meet.

Area of Origin

The location in three dimensional space that blood that produced a bloodstain originated. Impact and angle are used to determine the origin.

Cast Off

A bloodstain pattern that is created when blood is flung from a blood bearing object into motion onto a surface.

Arterial Spray

A characteristic bloodstain pattern containing spurts that resulted from blood exiting under pressure from an arterial joint.

Expirated Blood Pattern

A pattern created by blood that i expelled out of the nose, mouth, or respitory system as a result of air pressure/flow

Void

An area within a deposited spatter pattern that is clear of spatter, caused by an object or person blocking the area at the time of the splatter.

Transfer Spatter

A bloodstain pattern created when a surface that carries wet blood comes in contact with a second surface.

Flow Pattern

A bloodstain pattern formed by the movement of small or large amonts of blood as a result of gravitys pull.

Skeletonization

The process by which the edges of a stain dry to the surface in a specific perid of time on enviormental and surface.

Drip Trail Pattern

A pattern of bloodstains formed by the dripping of blood off a moving surface or person in a recognizable pathway, it's different from other patterns.

Cuticle

The scale structure covering the exterior of the hair.

Cortex

The main body of the hair shaft.

Medulla

A cellular column running through the center of the hair.

Anagen Phase

The initial growth phase during which the hair follicle actively produces hair.

Catagen Phase

A transition stage between the anagen and telogen phases of hair growth.

Telogen Phase

The final growth phase in which hair naturally falls out of the skin.

Follicular Tag

A translucent piece of tissue surrounding the hairs shaft near the root it contains the richest source of DNA associated with hair.

Nuclear DNA

DNA present within the nucleus of a cell this form of DNA is inherited from both parents.

Mitochondrial DNA

Inherited maternally from mom.

Natural Fibers

Fibers derived entirely from animal or plant sources.

Manufactured Fibers

Fibers derived from either natural or synthetic polymers the fibers are typically made by forcing material through a spinneret.

Polymer

A substance composed of a large number of atoms these atoms are usuallly arranged in repeating units of monomers.

Molecule

Two or more atoms held together by bonds.

Explosion

A chemical or mechanical action caused by combustion, accompanied bycreation of heat and rapid expansion of gases.

Oxidizing Agent

A substance that supplies oxygen to a chemical reaction.

Deflagration

A very rapid oxidation reaction accompanied by the generation of a low intensity pressure wave that can disrupt the surroundings.

Detonation

An extremely rapid oxidation reaction accompanied by a violent disruptive effect and an intense, high speed shock wave.

Low Explosive

An explosive with a velocity of detonation less than one thousand meteres per second.

Black Powder

Normally a mixture of potassium nitrate, carbon, and sulfur.

Safety Fuse

A cord containing a core of black powder, used to carry a flame at a uniform rate to an explosive charge.

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