| accelerants | Flammable liquids or solids that may have been used to start or sustain a suspicious fire.
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| accreditation | Recognition by a body or organization external to a lab that inspection and evaluation of the laboratory have determined that its work meets high professional, predefined standards.
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| ACE-V | method An acronym that stands for analysis, comparison, evaluation, verification, which are the four steps in the analysis and comparison of a latent print impression with a known.
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| acid phosphatase | An enzyme usually found in large quantities in human semen (but also in other tissues and species), used as the basis for a preliminary test for semen.
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| AFISs | Automated Fingerprint Identification Systems; several AFISs are commercially available for the imaging, storage, and rapid retrieval of single fingerprints; national system maintained by the FBI is called IAFIS (for Integrated AFIS).
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| alibi | An innocent explanation of events used by a person accused or suspected of a crime.
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| alibi known control | A specimen obtained from a known source that might be the source of the evidence; usually collected because suspects suggest it (for an alibis).
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| alteration | A change in the physical appearance or meaning of something, often only slight.
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| alternate light source | A high-intensity white light source filtered to emit only a limited range of wavelengths of visible light.
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| anabolic | Promotes cell growth and division, resulting in growth of muscle tissue and sometimes bone size and strength.
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| anagen phase | The active growth phase of the hair follicle.
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| analgesics | Drugs used to reduce or eliminate a patient's perception of pain.
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| angle of incidence | The angle at which a blood droplet impacts a surface, measured with respect to an imaginary line perpendicular to that surface.
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| antemortem | Occurring before death.
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| anthropometry (bertillonage) | A system of bodily measurements devised by Alphonse Bertillon for personal identification of persons with criminal histories; eventually supplanted by fingerprints.
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| antibodies | Substances made by vertebrates in response to a "foreign" molecule, virus, or cell invading the body; specifically directed against the invader and designed to neutralize it and/or rid the body of it.
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| anticoagulant | A chemical substance, such as EDTA or sodium citrate, which, when added to whole blood, prevents it from clotting.
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| antigens | Substances, often proteins, that elicit the formation of specific antibodies if injected into an animal of a different species.
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| architectural paints | Paint that is used on houses, buildings, and other structures.
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| attenuated total reflectance (ATR) | An infrared sampling technique that depends on passing an IR beam through a crystal in a way that a small portion of the beam emerges from the crystal and can interact with a sample in intimate contact with the crystal.
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| authenticate | To prove that something is real, true, or what it is said (purported) to be.
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| automatic | A firearm that will begin to fire projectiles as soon as the trigger is pulled and continue to fire until the trigger is released or it has run out of ammunition.
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| automotive paints | Paints that are used primarily on automobiles, trucks, and other motor vehicles.
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| ballistics | The science of projectiles in flight; ballistics is not firearms identification.
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| basic fingerprint patterns: | arches, loops, and whorls The basic overall fingerprint patterns; variations and subcategories occur within these major classes.
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| biometrics | Use of measurements or portions of complex patterns from the human body to build a database that can then be used to "verify" the "identity" of person within that database.
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| blank control | In many tests, a clean sample containing no specimen, used to ensure that the test is working properly.
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| blood cells | Refers collectively to the red blood cells (erythrocytes) and to all the categories of white blood cells (lymphocytes, monocytes, basophils, neutrophils, and eosinophils).
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| blood spatter pattern | A pattern of dried blood on a surface resulting from an event that caused blood to exit the body and/or be broken into particles and distributed by force.
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| breech face | The surface of a firearm, usually machined, against which the cartridge case is forced by the expanding gases as a result of being fired.
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| bullet recovery tank | Usually a large horizontal or vertical stainless steel tank filled with water and used to stop the flight and allow recovery of a projectile when a firearm is fired into it.
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| burn pattern | The pattern of charring and burning left after a fire has been extinguished that may give insight into how the fire developed.
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| caliber | The inside diameter of a gun barrel, in hundredths of an inch or millimeters.
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| camera | An analog or digital device equipped with a lens and capable of recording images on film or an electronic storage medium.
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| carbon strip or tube absorption | A technique for processing debris from a suspicious fire where the vapors above the debris are absorbed on activated carbon and then washed off with a solvent for analysis.
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| cartridge | The assembly of a bullet, gunpowder, and primer in a casing that is placed in the chamber of a firearm.
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| catagen phase | The hair follicle phase in which hair growth stops.
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| catalyst | A substance that speeds up a chemical reaction without being changed or consumed; required in small quantities, because it is not changed by the reaction.
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| certification | The determination by an appropriate organization, after an application that includes qualifications, experience, and an examination, that an individual meets a high level of skill in the area of expertise in which he or she works.
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| charred documents | A document that has been partially burned or heated until it has turned a very dark color and can no longer easily be read.
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| chromatography | A process that separates a mixture of different chemicals into its individual components, often for the purpose of analysis.
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| chromosomes | Physical carriers of DNA (and thus of inheritance information) from one generation to the next; every species has a specific number of chromosomes.
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| class characteristics | Characteristics that define a class or category of items or objects but are not alone sufficient to define individuality; often an intentional result of manufacturing; examples include shoe size and pattern, tire tread pattern and width, first-level fingerprint pattern, and bullet caliber.
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| classification (identification) | To place things into groups according to their basic characteristics.
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| classification system | A method of organizing large files of 10-print cards according to the features of the fingerprints; in the United States, a modified Henry system of classification was used.
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| club drugs | Any of a group of drugs whose primary abuse is associated with marathon youthful dance parties.
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| CODIS, AFIS, and NIBIN | The acronyms given to databases of DNA profiles, fingerprints, and firearms evidence images, respectively, maintained for investigative purposes and used to search evidence patterns against previously existing patterns.
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| cold case | An investigation that has become inactive for a period of time, for a variety of reasons, although the case has not yet been solved.
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| collected writings | Writing samples obtained from a variety of sources that represent a valid sample of an individual's writing.
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| Combined DNA Index System (CODIS) | A large system of interconnected local, state, and national databases containing DNA profiles; authorized by Congress in 1994 and recently amended to permit databasing of suspects or arrestees provided the latter is legal under applicable state law.
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| combustion | The combination of a fuel with oxygen to produce highly oxidized products and heat.
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| comparison specimen | A separate specimen taken of a material for comparison purposes; in fire investigations, a sample of surface or substratum on which ignitable liquid residue might be present.
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| confirmatory | test A test that, when positive, proves that the material or substance tested for is actually present.
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| containment | Confining a rapid, exothermic reaction within a sturdy container until it develops sufficient force (pressure) to shatter the container.
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| contamination | Refers to unintended, potentially unrecognized, biological material in or on a biological evidence specimen, which could cause difficulty in interpreting the results of some tests under some circumstances.
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| contemporaneous | Happening or existing in the same period of time.
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| control specimens | Separate specimens included in a test protocol to ensure that the test is performing properly.
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| controlled experiments | Experiments carefully designed to test one variable of a hypothesis.
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| controlled substance | A drug that is named in either federal or state controlled substances statues as illegal to possess except when prescribed by a physician.
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| controls | In general, required to ensure that a laboratory test is working properly or to permit a proper comparison; the major types important in forensic investigations are blank, known, and alibi known.
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| copying machine | A machine that makes copies of documents using one of several different duplication processes.
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| coroner | An elected official whose responsibility is to look into suspicious or unattended deaths.
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| corpus delicti | Latin term for the facts necessary to prove a particular crime.
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| cortex | The primary structure of the hair shaft.
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| crime scene photography | Technically proper photography of a crime scene for purposes of complete documentation.
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| crime scene security | Limiting and controlling access to a crime scene and maintaining records of who was present.
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| criminal profiling | Application of psychology and of knowledge developed from past similar offenses and offenders to help create a hypothetical picture of an offender in an unsolved case.
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| criminalistics | The recognition, classification (identification), individualization, and evaluation of physical evidence using the methods of science.
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| cross-projection sketch | Sketch of a three-dimensional room or structure in two dimensions, by "collapsing" the walls and ceiling fl at in the sketch.
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| crystal tests | Tests in which the formation of characteristic crystals constitutes a positive result.
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| cursive writing | Writing that is written with rounded letters that are joined together.
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| cuticle | The impervious outer layer of cells that protects hair.
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| database | A computer file containing the DNA profiles of convicted offenders, evidence from unsolved cases, or missing persons or their relatives.
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| Daubert standard | A broad set of criteria laid out by the U.S. Supreme Court opinion in the Daubert case for the admissibility of scientific evidence, with the judge as the "gatekeeper" responsible for applying those criteria.
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| defacing | Attempting to render a serial number unreadable.
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| delusterant | An opaque pigment (usually white) that is added to manmade fibers to reduce their shininess.
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| dependence | When an individual becomes so strongly attached to a drug that the individual either becomes physically sick or mentally disoriented when its use is discontinued.
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| deposit | Material that is laid down or left behind by a physical process.
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| depth of field | A photographic term describing the distance behind and in front of the subject that is in focus; inversely related to lens opening.
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| detonate | Causing an explosive material to release energy in the form of an explosion.
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| development (enhancement, visualization) | Physical or chemical treatment or special illumination, or a combination of both, that enhance the visibility of ridge detail of a latent fingerprint impression sufficiently to enable comparison.
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| differential extraction | A process by which an analyst can separately isolate male and female DNA from a mixture of female epithelial cells and male sperm cells, such as might be found in sexual assault evidence.
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| diffuse reflectance infrared | Fourier transform spectroscopy (DRIFTS) An infrared sampling technique where the sample is ground to a fine powder and mixed with a nonabsorbing powder and the spectrum is obtained by collecting IR radiation that is diffused by the mixture.
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| diluents | Materials that are added to a drug to add bulk and thereby make it easier to handle.
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| direct physical match | A jigsaw fit match of pieces of a randomly fractured solid object that shows the pieces were originally part of the same item.
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| disguise | To give a new appearance in order to hide its true form.
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| disputed parentage | Refers in law and forensic science to a case where there is a question as to whether a person is the true biological father (or mother) of a particular child.
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| DNA polymerases | Enzymes that can catalyze the synthesis of double-stranded DNA from another primed strand.
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| documentation | Creation of a detailed, complete record of a crime scene, including notes, sketches, photographs, and possibly audio- or videotape.
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| driving while impaired | Operating a motor vehicle while one's judgment or physical capabilities are reduced by alcohol or drugs.
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| drug | A drug is a substance that produces a physiological or psychological affect that is significant, occurs within a reasonable time after dosing and results from an easily ingested dose.
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| drug-facilitated sexual assault | A sexual encounter where one party, the victim, has been rendered unable to resist or voluntarily participate by ingestion of a drug, often in combination with alcohol.
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| drug-facilitated sexual assault | Sexual assault perpetrated on a victim who cannot consent because of mental impairment by a drug or drugs.
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| duty to preserve | An obligation imposed by courts on law enforcement agencies and personnel to preserve certain audio and video recordings for a specified length of time.
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| dye | A deeply colored material that dissolves in a solution or an object to give it a desired color.
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| dye stains | Chemicals that stain cyanoacrylate polymer and can thus be used to further enhance the visibility of Super Glue–developed latent prints; some of the chemicals require the use of alternate light or laser illumination.
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| electromagnetic spectrum | The full range of electromagnetic radiation, from low-energy microwaves (transmission of telephone calls) to high-energy gamma rays, including the visible portion to which our eyes are sensitive and X-rays used by doctors to visualize our bones.
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| elimination fingerprints | A ten-print set of inked (or live-scanned) fingerprints from everyone who enters the secure crime scene area.
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| entomology | The branch of zoology that deals with insects.
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| enzyme | A protein that can speed up a chemical reaction without being consumed by it; an enzyme is a protein catalyst.
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| ESD | A Electrostatic Detection Apparatus; an instrument developed in England specifically for making indented writing visible on a clear cover sheet without altering the original document.
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| etching | The use of strongly acidic or basic chemicals to dissolve away metal in a controlled manner.
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| evidence collection and preservation | The actual seizing and packaging of physical evidence items for submission to a forensic science laboratory in a manner that ensures integrity of the evidence, and/or documenting scene patterns that cannot be physically collected.
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| evidence collection techniques | Methods used to collect evidence when the intact item or item containing the evidence cannot be seized; usually includes using forceps or tape lifts at scenes; shaking, scraping, and vacuuming may be done in the laboratory or as last resorts.
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| evidence recognition | Determination of which physical evidence items and/or patterns are relevant to the case as opposed to being part of the scene background.
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| exclusion | A conclusion that a known and a questioned specimen do not match and could not have had a common origin.
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| exclusionary value | When physical evidence is of a type that cannot be individualized, but only associated, it may have significant value by excluding the possibility of a common source, and exclusion is an absolute conclusion.
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| exothermic | Giving off heat, usually applied to a chemical reaction.
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| expert witness | An individual who by training, knowledge, or experience is a specialist in a subject and therefore is qualified to give opinion testimony in legal settings.
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| explosive | A chemical material that undergoes a very rapid chemical reaction on being heated, struck, or otherwise energized with production of large volumes of gas.
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| explosive residues | Materials that can be found on debris from an explosive incident that may contain trace amounts of the unchanged explosive or chemical reaction products produced by the explosive reaction.
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| extortion note | A communication usually demanding some form of payment to the writer to prevent his/her carrying out a threat.
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| fire point | The temperature at which a fuel in the presence of air will ignite without an external source of ignition.
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| firearm | A device for accelerating a projectile to a high speed and sending it toward a selected target.
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| firearms | comparison microscope Two reflected-light microscopes linked with an optical bridge used for comparison of objects using reflected light.
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| firing pin | The pin or rod in the firing mechanism of a firearm that strikes the cartridge primer to fire the cartridge.
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| firing pin impression | The impression left by the firing pin on the primer cup portion of a cartridge after it has been struck (fired).
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| first responder | The first police officer or investigator to arrive at and witness a crime scene, often a uniformed patrol officer.
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| flaming combustion | When oxygen and fuel are both in the gaseous state, the combustion reaction is rapid, producing light as well as heat (flame) at a high rate.
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| flammable range | The range of concentrations of a fuel in air that will support combustion.
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| flash point | The temperature at which a fuel in the presence of oxygen in air has sufficient material in the gaseous phase to be ignited by a small flame or other source of ignition.
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| float glass process | The most common modern manufacturing process for making fl at glass by floating the molten glass on a pool of tin while it cools.
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| forensic | Having to do with the law.
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| forensic biology | Today, refers to the preliminary examination of biological evidence in blood transfer and sexual assault cases, much of which will go on to be analyzed for DNA; also sometimes used to refer to subdisciplines like forensic botany.
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| forensic science | Science applied to legal problems.
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| forensic serology | Refers to the preliminary examination and genetic typing of biological evidence in blood transfer and sexual assault cases before DNA analysis was available.
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| forensics | The art of argumentative discourse, debate.
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| forgery | To make an illegal copy of something in order to deceive.
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| fountain pen | A pen where the point (nib) is supplied with liquid ink from a refillable container inside the pen.
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| friction ridge skin | The skin on the fingertips, palms of hands, and soles of feet, characterized by patterns of hills and valleys.
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| Frye rule | The basic standard enunciated by the U.S. Supreme Court in 1929 for admissibility of new scientific or technical evidence, which placed emphasis on general acceptance in the appropriate scientific community.
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| f-stop/lens opening | A selectable parameter on a camera that defines the amount of light entering the lens.
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| functionality | The ability of a firearm to fire a projectile when the trigger is pulled.
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| gas chromatography | A chromatographic technique where the mixture to be separated is vaporized and the separation occurs during partition between the gas and a solid or liquid absorbent.
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| genetic code | The correspondence between the sequence of bases in DNA, taken three at a time, and the amino acids that make up the proteins.
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| genetic markers | Refers to blood groups, isoenzymes, and other substances used to help establish partial individuality (narrow the size of the included group) before DNA typing was available.
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| glowing combustion | When oxygen is in the gaseous state but the fuel is not, the combustion reaction is slowed, producing heat but little light.
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| grammar | The rules concerning how words are used, change their form, and combine with other words to make sentences.
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| grooves | The spiraling depressed areas inside the barrel of a handgun or rifle.
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| gunshot residue (GSR) | Materials created by the firing of a firearm that are dispersed by the force of the expanding gases.
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| hallucinogens | Drugs taken to cause a significantly altered mental state, often including hallucinations.
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| handguns | Firearms, usually a foot or less in length, designed to be held in one or both hands when fired.
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| handprinting | Noncursive writing where letters are individually formed and normally not connected.
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| heated headspace | A technique for processing debris from a suspicious fire in which the debris is warmed in a closed container and then a sample of the vapors above the debris is removed for analysis.
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| high-velocity blood pattern | A pattern caused by blood spattering in all possible directions from extreme force, such as might happen with a gunshot or explosion; many of the droplet stains are very small (aerosol spray size) and often more numerous than in a medium-velocity pattern.
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| HPLC | High-performance liquid chromatography; a separation technique using high pressure to force a solvent through a tube packed with an absorbent.
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| hypothesis | An as yet unproven attempt to develop an explanation for an observation or series of related observations.
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| ignitable liquids | Liquid materials that can be ignited in the presence of air.
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| illicit | Proscribed by law (illegal).
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| immunological tests | Tests based on the use of specific antibodies to demonstrate the species or nature of a biological specimen.
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| impressions | Negative imprints or indentations of an object.
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| imprint | A mark (pattern) that is essentially two-dimensional left by an object on a hard receiving surface through contact with another object; an imprint has very little depth.
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| inconclusive | A conclusion by an examiner that a comparison of known and questioned specimens permits neither an identification nor an exclusion.
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| indentation | A three-dimensional mark (pattern) left in a deformable object through contact with another object.
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| indented marks | Marks left in a surface by pushing a tool into the surface.
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| indented writing | When writing on the top sheet of a stack or pad, impressions of that writing are impressed into the sheets below.
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| indirect physical match | A secondary physical match between soft, pliable objects, such as torn fabric, between pieces of a randomly fractured object with some pieces missing, or between cross sections of a broken wooden object.
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| individual characteristics | Accidental (unintentional) characteristics resulting from wear or random markings on items during manufacture; a sufficient number of matching individual characteristics between a known and questioned specimen can permit an examiner to make an individualization.
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| individualization | Demonstration that an object is unique, even among members of the same class, or that two separate objects were at one time a single object (had a common source or origin).
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| infrared spectroscopy | The use of the measurement of the absorption of infrared radiation by a substance to characterize that substance.
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| ink compositions | The mixtures of solvent and dyes or pigments that make up the ink.
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| ink eradicator | A fluid used to decolorize ink on a document to make it invisible.
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| insufficient detail for comparison | A conclusion by an examiner that a questioned specimen lacks enough class and/or individual characteristics to do a proper comparison with knowns.
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| iodine fuming | A latent print development technique in which solid iodine is sublimed to iodine vapor, which can then deposit on the ridge patterns of a latent print impression, especially on porous surfaces.
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| keratin | Fibrous, tough, and insoluble protein that forms the hard but nonmineralized structures such as hair, fingernails, and toenails.
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| known control | A specimen from a known source; it could be known blood, known human blood, known animal blood, or known blood from a particular person; for DNA, it could be a buccal (cheek) swabbing from a known person.
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| land impressions | The depressed helical grooves in a bullet left by the lands inside the barrel from which it was fired.
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| lands | The spiraling raised areas between the grooves inside the barrel of a handgun or rifle.
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| laser | A special light source that emits light that is of a single wavelength (monochromatic light) and, further, vibrates in a single plane; extremely efficient at exciting chemicals that absorb its wavelength, and can then fluoresce or phosphoresce as the molecules relax.
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| latent print | A fingerprint impression that requires development or special illumination to reveal the ridge detail in sufficient detail for comparison.
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| layer structure | Where multiple layers of paint have been applied, a paint chip will show the number, color, and thickness of the layers.
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| lens | An optical component of a camera that focuses light onto the recording medium (film or digital recorder); "standard" lenses with a 50 mm focal length provide a "normal eyeball" view of the subject, "wide angle" lenses provide more peripheral views, and "telephoto" lenses provide closer but narrower views.
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| level I , level II, and level III detail | Terms used to describe the overall fingerprint pattern, such as loop, whorl, arch (level I), the minutiae (level II), and pore numbers, locations and relationships, and the shape and size of ridge features (level III).
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| licit | Not prohibited by law.
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| light box | A box with a very even light source behind a piece of ground or translucent glass or plastic, which is used to backlight an object.
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| linkage | A connection, relationship, or association between objects and/or persons. Locard Exchange Principle States that when two objects come into contact, there is a mutual exchange of material between the objects across the contact boundary.
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| low explosives | Materials that will burn rapidly, but not detonate, unless contained.
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| low-velocity blood pattern | A pattern caused by blood falling onto a surface, influenced only by the force of gravity.
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| magazine | The container for the cartridges in most semiautomatic firearms.
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| magnetic brush technique | A variant of powder dusting that uses a magnet and magnetic particles instead of a brush and powder.
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| mass spectroscopy | A technique for identification of materials by bombarding them, while in the gas phase, with a high-energy species (usually electrons) and causing them to fragment into ions whose mass is determined by a mass sorting device
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| materials evidence | Physical evidence, either trace or transfer, that is usually chemically or microscopically analyzed and used to make connections.
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| mechanical dislocation | The scraping or shaking of an item of physical evidence over a clean surface to dislodge any trace evidence clinging to the surface.
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| medical examiner | A medical doctor, usually a forensic pathologist, whose responsibility is to determine the cause and manner of suspicious or unattended deaths.
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| medicolegal | A reference to forensic or legal medicine; in the past, the term could encompass many activities that would be called "criminalistics" today.
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| medium-velocity blood pattern | A pattern caused by blood spattering in all possible directions from moderate force; many of the droplet stains are smaller than low-velocity pattern droplets and more numerous.
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| medulla | A canal that runs up the center of the cortex of a hair and is usually air filled in forensic samples.
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| melanin | A natural brown pigment that gives most hair its color.
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| microsatellite | A synonym for STR.
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| minisatellite | Refers to a VNTR region of DNA in which the repeat units are 30 to 50 bases long; the RFLP technique was used to type "minisatellite" regions of DNA.
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| minutiae | Features of the friction ridge skin pattern on fingertips that make the overall pattern individual; ending ridges, bifurcations, and dots are the primary minutiae.
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| mitochondria (sing., mitochondrion) | Structures that contain a small amount of DNA and are found in the cell, outside the nucleus, responsible for making energy for the cell.
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| mitochondrial DNA (mtDNA) | The DNA contained in the mitochondria of the cell; inherited only from an individual's mother and passed along a maternal line from generation to generation.
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| mitosis | Cell division, in which a single cell replicates its DNA, then divides allocating to each daughter cell a complete complement of the original DNA.
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| modus operandi (MO) | The habits of a criminal; actions a criminal repeats in different crimes that may help investigators recognize that the same person was responsible.
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| narcotic | A drug found as a natural constituent of the opium poppy or a derivative thereof.
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| natural fibers | A fibrous material composed of a material found in nature either in plants or animals.
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| natural law | A generally accepted explanation of a phenomenon or a series of phenomena so thoroughly tested that it is regarded as highly reliable.
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| NIBIN | The national database primarily of images of cartridge cases used to try to associate evidence cases with test-fired cases from seized weapons or cases collected from shooting incidents where the gun involved is not known.
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| ninhydrin | A chemical for latent print impression enhancement especially on porous surfaces; postninhydrin treatments can further increase the value of this method.
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| normal variation | That variation in writing characteristics seen by examination of numerous examples of an individual's writing.
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| notes | Written or audiotaped records for documenting a crime scene that contain information such as initial conditions, names and contact information for witnesses, license plate numbers of vehicles in the vicinity, and that may be constructed to include scene security logs, photo logs, and evidence logs.
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| nuclear/genomic DNA | The DNA found in the chromosomes in the nucleus of the cell; the terms "nuclear DNA" and "genomic DNA" are synonymous.
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| nucleotide | A molecule that is made up of a nitrogenous base (A, T, C, or G), a ribose sugar component, and phosphate; the building blocks of nucleic acids (DNA and RNA).
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| nucleus | A membrane-enclosed structure within a cell that contains the chromosomes, and therefore, the nuclear DNA.
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| oblique lighting | Using a bright light at a very low angle (grazing angle) to a document to make indentations on the sheet more visible by shadowing them.
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| odontology | The study of the physiology, anatomy, and pathology of teeth.
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| optical properties | The way a material interacts with light, such as refractive index and dispersion.
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| p30 | A protein found in high concentrations in human semen and used as the basis for a specific semen identification test; also known as PA.
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| PA | Short for "prostatic antigen"; a protein found in high concentrations in human semen and used as the basis for a specific semen identification test; also known as p30.
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| paint smears | A very thin film of paint transferred to another surface as the result of glancing contact.
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| particle size distribution | A quantitative estimation of the percentages of particles that fall into defined size ranges in a soil sample.
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| pathology | The medical specialty that deals with disease and the bodily changes caused by disease.
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| peroxidases | Enzymes that catalyze the oxidation of a dye to form a new compound that is a different color.
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| physical anthropology | The study of human evolution, as revealed by the skeleton or by evolutionary patterns in DNA.
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| physical developer | A special silver-based solution for enhancing latent print impressions by reacting with the fatty (lipid) components; a chemical method.
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| physical matches | Matches between or among pieces of a randomly fractured, torn, or cut objects that might show that the pieces were originally part of the same item.
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| physiological | Relating to or arising from the functioning of living organism.
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| pigment | A very finely divided, highly colored material that does not dissolve, but rather is suspended in a solution or dispersed through an object to give it a desired color.
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| plasma | When treated with anticoagulant, the straw-colored liquid portion of blood after the cells have settled.
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| plastic (impression) print | A three-dimensional fingerprint indentation in a soft receiving surface, such as tar, margarine, or Silly Putty.
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| platen | A perforated plate used to firmly hold an object using air pressure.
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| plea bargaining | A negotiation between a defendant and his attorney on one side, and the prosecutor on the other, in which the defendant agrees to plead "guilty" or "no contest" to some crime, in return for reduction of the severity of the charges or a lighter sentence recommendation.
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| point of origin | The location or locations where a fire started.
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| polymerase chain reaction (PCR) | A process used to make many copies of a defined segment of DNA, using a special kind of DNA polymerase that is stable to high temperatures; PCR is now one of the steps in all forensic DNA analysis.
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| positive identification | In the pattern evidence context and fields, identification means individualization; "making the identification" means the examiner is concluding the known and the questioned items had a common origin.
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| postmortem | Occurring after death.
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| powder dusting | An old but tried-and-true method for visualizing fingerprints on nonporous surfaces.
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| powder pattern | A pattern found on an object close to the barrel of a fired weapon caused by small particles of lead, or partially burned gunpowder and carbon smoke that follow the projectile out of the barrel.
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| preliminary test | A nondefinitive screening test used to give an indication that something might be present (like blood, or a body fluid); positive results indicate the need for further tests.
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| primary high explosives | Explosive material that is caused to explode fairly readily by physical shock, electrical spark, or other disturbances.
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| primer | The shock-sensitive portion of the cartridge that provides the initial spark or flame that causes the cartridge to fire.
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| probable cause | Sufficient reason based on known facts to believe a crime has been committed or that certain property is connected with a crime.
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| projectile (bullet) | An object that can be fired or launched.
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| psychiatry | The branch of medicine concerning the diagnosis, treatment, and prevention of mental illness.
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| psychological | Relating to or arising from the mind or emotions.
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| purification | The physical or chemical process whereby a substance is separated from other accompanying substances or impurities to obtain the pure chemical substance.
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| pyrolysis | The process whereby a material with little vapor pressure is broken down by heat, usually in the absence of oxygen, to produce flammable products with significant vapor pressure.
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| questioned document | Any means of communication that is suspect, entirely or in part, as to authenticity or origin.
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| questioned specimen | A piece of potential evidentiary material that will be examined and may be compared to a control specimen.
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| radial fracture lines | Fracture lines in glass that appear to radiate outward from the center of the point of force.
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| rave | A dance party, usually lasting all night, that tends to be characterized by stroboscopic light effects, loud music, and high human density and attended ordinarily by youthful participants.
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| recognition | To know something because one has seen, heard, or experienced it before.
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| reconstruction | Formulation of a "best theory" of a set of events in a case based on consideration of all the available evidence and information.
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| reconstruction | The process of putting together the evidence available with the objective of understanding the nature and sequence of events that created it.
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| reconstruction patterns | Pattern evidence that is principally useful to help reconstruct past events; blood spatter, glass fractures, fire burn, and track and trail patterns are examples.
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| reenactment | A hypothetical rendition of a set of events at a crime scene partially based on a reconstruction theory, but with all the "blanks" filled in to make a smooth, continuous story.
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| refractive index (RI) | The refractive index of a substance is the ratio of the speed at which light passes through a vacuum to the speed that light passes through the substance.
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| regenerated fibers | Fibers made by dissolving cellulose-based material and forcing it through fine holes into a solution that causes it to immediately solidify, thereby transforming a natural vegetable material into a man-made fiber.
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| requested writings | Writing samples obtained from an individual either voluntarily or as the result of a court order.
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| restriction fragment length polymorphism (RFLP) | The original kind of DNA typing used in forensic science, now obsolete in forensic work.
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| revolvers | Handguns that have rotating cylindrical cartridge holders that usually hold five to nine cartridges and allow the weapon to fire semiautomatically until the cartridges are expended.
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| rifle | A firearm, usually two or more feet in length, designed to be fired from a shoulder-held position.
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| rifling | The helical grooves cut or impressed into the barrel of a handgun or rifle to cause the exiting projective to spin.
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| safety | A component of most firearms that prevents it from firing without the trigger being pulled or that locks the trigger so it cannot be pulled, or to prevent firing even if the trigger is pulled.
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| SANEs | Sexual assault nurse examiner.
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| SART | Sexual assault response team.
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| scanning electron microscope (SEM) | A microscope that uses high-energy electrons rather than light for image formation and is capable of very high magnification.
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| scene search | A detailed, systematic search of a crime scene with the objective of noting every condition and every relevant item of physical evidence.
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| scene survey | A preliminary walk-through and look at the overall scene to try to establish the type of scene, note any transient physical evidence, and get a first impression of the relevant physical evidence.
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| scientific method | The multistep method by which scientists approach problems, formulate them for experimental inquiry, and validate their conclusions.
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| secondary high explosive | Explosive material that can be safely handled but will explode violently when subjected to an electrical spark or small flame.
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| SEM/EDX | A SEM that is equipped with an energy-dispersive X-ray spectrometer, which allows elemental analysis of individual objects seen in the SEM.
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| semen | The male reproductive fluid, ejaculated through the penis at male orgasm, and consisting of sperm cells suspended in seminal plasma.
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| semiautomatic | A firearm that fires a projectile each time the trigger is pulled until out of ammunition.
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| seminal plasma | The fluid in which sperm are suspended in whole semen; consists of fluids contributed primarily by the prostate but also by the Cowper's glands.
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| sequence | Forms the basis for genetic information; specifies the structure of all the proteins that are made from the DNA template and is the basis of individuality.
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| serial number restoration | The attempt to recover a serial number that has been rendered unreadable.
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| serum | The straw-colored liquid portion of blood remaining after whole blood has been allowed to clot.
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| sexual assault evidence collection kits | Usually packages or boxes, containing numerous containers, tools, and labels, for the collection of clothing and other evidence, including evidence from the body, of sexual assault complainants; designed to allow for proper packaging, labeling, and preservation of sexual assault evidence.
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| shape and form | Refers to the ability of the human mind to recognize individual characteristics in complex shapes or forms, such as a human face; handwriting and morphological hair comparisons are examples.
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| shock wave | A region of sufficiently high pressure traveling through a gas at a high velocity that it can cause physical damage to objects it encounters.
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| short tandem repeat (STR) | A VNTR where the repeat unit is short, from two to six bases in length; all the regions used for forensic STR DNA typing have four or five base repeats.
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| shotgun | A long gun that usually fires a large number of small metal pellets at one time, which is designed to be used for hunting birds and small animals.
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| shotgun shells | Ammunition that serves the same purpose for a shotgun as a cartridge in a handgun or rifle.
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| sketches | Drawings of scenes with measurements or to scale, depicting the correct spatial relationships between scene fixed points and evidence items.
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| skill level | The level of fine motor control displayed in an individual's writing.
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| slug | A single projectile used in a shotgun shell instead of pellets, analogous to the bullet in the handgun or rifle cartridge.
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| small particle reagent (SPR) | A formulation of small inorganic particles in special suspension that can be applied to latent print impressions to enhance the visibility of ridge pattern features; can be useful with weathered latents, especially those that have been exposed to moisture.
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| smokeless powder | A nitrocellulose-based explosive or propellant that produces little smoke.
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| Sniffers | Mechanical devices that detect gases in the atmosphere other than the normal nitrogen and oxygen and that are used to look for traces of flammable liquid after a fire has been extinguished.
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| soda lime glass | The most common type of glass including window glass and bottle glass that has as its major ingredients sand, soda (sodium carbonate), and lime (calcium oxide).
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| species of origin | The species from which an item of biological evidence originated, such as human, horse, cat, cow, etc.
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| spectral comparator | An instrument that has a number of light sources, filters, and a video camera used to examine documents in a way that greatly increases what one can "see" on that document over what our eyes can ordinarily observe.
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| spectroscopy | The interaction of electromagnetic radiation with a chemical to give a pattern characteristic of that material's interaction with the radiation.
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| sperm | Short for spermatozoon ( pl . spermatozoa); the male reproductive cell produced in the testes and stored in the seminal vesicles until ejaculated.
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| steam distillation | A technique for processing debris from a suspicious fire where the debris is mixed with water in a large fl ask and the mixture heated until a sizable portion of the water has boiled and been condensed; the condensate is examined for accelerant.
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| stimulants | Drugs taken to produce feelings of high energy and to suppress the desire to sleep.
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| striated marks | Marks left in a surface by the sliding of a tool across that surface.
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| Striation | A number of parallel or nearly parallel lines or scratches on a surface inscribed by another object passing over that surface.
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| substratum | comparison specimen A sample of the material or surface on which biological evidence is deposited.
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| suitability for comparison | A latent print impression that has sufficient ridge detail for an examiner to determine it to be suitable for comparison with known print impressions.
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| super Glue (cyanoacrylate) | An adhesive material that polymerizes (the chemicals in it react to form a solid matrix) in place when applied to surfaces; Super Glue vapors, produced by heating it, interact with latent fingerprint residue and produce the solid matrix polymer on the ridges.
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| surface coating (sizing) | Material placed on the surface of paper to smooth the roughness of the interwoven fibers.
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| synthetic fibers | A fibrous material composed of material that does not occur in nature, but rather is man-made.
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| tandemly repeated sequence | A sequence of bases in DNA that is repeated in a head-to-tail fashion several to many times.
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| tangential fracture lines | Fracture lines in glass that appear to encircle, or form a polyhedron, around the point of force.
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| tape lift | The use of clear sticky tape to remove trace evidence from the surface of a piece of physical evidence.
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| telogen phase | The third growth phase of the hair follicle, which is a resting period.
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| theory | A plausible explanation of a phenomenon or a series of phenomena that has gained some general acceptance; a well-tested hypothesis.
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| threatening letter | A communication usually threatening to harm an individual or individuals if some demand is not met.
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| TLC | Thin-layer chromatography; a separation technique using a plate with a thin layer of an absorbent and capillary action to move a solvent up the plate.
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| toolmark | A marking on a surface caused by the pressing or sliding of a tool into or across the surface.
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| toxicology | The medical study of the chemistry, effects, and treatment of poisonous substances and drug action and detection in the body.
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| trajectory | The flight path from muzzle to target of a projectile fired by a firearm.
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| transcription | The process by which messenger RNA (mRNA) is synthesized from DNA while preserving the base sequence information.
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| transfer evidence | Physical evidence that is transferred between objects as the result of contact.
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| transfer medium | The material that records markings (handwriting or mechanical printing) on a receiving surface.
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| translation | The process by which a messenger RNA (mRNA) template is used by the cell to assemble proteins based on the genetic code.
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| trier of fact | The person or persons charged with critically evaluating the facts as presented in a legal case. The judge or the jury.
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| trigger pull | The amount of force needed to pull (depress) the trigger sufficiently for the firearm to fire.
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| TWG and SWG | Working groups made up of highly experienced individuals with technical or scientific expertise in a particular subject, who meet to develop standard procedures to be used in their area of expertise.
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| twist | The direction in which the lands and grooves spiral down the inside of a handgun or rifle barrel.
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| typewriter | A machine with keys that are pressed to produce letters and numbers on paper.
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| under the influence | Acting while significant quantities of a drug are in an individual's system.
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| variable number of tandem repeat (VNTR) | Different individuals have different numbers of repeat units at many of the locations in DNA that feature tandemly repeated sequences; those different numbers of repeat units are "VNTR".
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| videography | The use of a video recording device, in this context, to document a crime scene.
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| visible (patent) print | A fingerprint impression that is visible with no enhancement or any special illumination.
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| visible spectrometers | Devices for examining a sample and determining its ability to absorb or reflect electromagnetic radiation in the visible portion of the spectrum.
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| watermark | A mark that is made on some types of paper during its production that can be seen only if it is back-lighted.
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| working hypothesis | An initial theory about what may have happened in a case based on observation of the crime scene; properly formulated, can generate predictions about physical evidence that are testable during the investigation, laboratory, and medicolegal stages of analysis.
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| wound ballistics | A subset of forensic pathology that examines the wounds and wound patterns made by various projectiles.
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| writing instrument | An item used by individuals to mark handwriting motions or mechanical printing on to a surface to prepare a more permanent record.
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| writing mechanics | The way an individual writes, particularly letter shapes and connections.
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2008 McGraw-Hill Higher Education