OSAC Lexicon
The OSAC Lexicon is a compendium of forensic science terms and definitions. This terminology tool was created to help bring consistency and understanding to the way terms are used by the various forensic science. Use of the OSAC Lexicon does not replace the need to reference the original published source.
The terms and definitions in the OSAC Lexicon come from the published literature, including documentary standards and technical reports. It is continually updated with the latest work from OSAC units, as well as terms from newly published documentary standards and standards elevated to the OSAC Registry.
Gradually terms are evaluated and harmonized by the OSAC to a single term. This process results in an OSAC Preferred Term. An OSAC Preferred Term is a term, along with its definition, that has undergone review and evaluation by the FSSB Terminology Task Group and has been approved by the FSSB. The FSSB recommends that subcommittees use OSAC Preferred Terms when drafting standards.
The OSAC Lexicon should be the primary resource for terminology and used when drafting and editing forensic science standards and other OSAC work products.
added materials (usually metal) which are placed in or around an explosive to intentionally produce additional property damage and injuries.
Discussion—(1) It should be noted that the term 'shrapnel' is also sometimes colloquially used to denote any pieces from a device that are fragmented by an explosion. (2) Shrapnel can also be included in some military ordnance.
Illumination from a light source at a low angle of incidence, or even parallel, to the surface of the item. Syn. oblique lighting, grazing illumination, raking lighting.
Illumination from a light source that is at a low angle of incidence, or even parallel, to the surface of the item. Syn., oblique lighting.
a property of fibers referring to the elongation of a fiber in relation to refractive indices.
Discussion—If the fiber is elongated in the direction of the higher refractive index, it is said to have a positive sign of elongation; if the fiber is elongated in the direction of the lower refractive index, it is negative.
to overwrite all available storage areas with a unique sector character sequence.
The acquisition of images of a single biometric modality from a subject at the same time.Sequential capture over a time scale ( < 1 second) that prevents confounding of bodyparts ( e.g., substituting left iris for right iris) can also be considered simultaneous capturein this context.
DNA sequence variations that occur when a single nucleotide (A, T, C, or G) in the genome sequence is altered; these variations may be used for distinguishing individuals, and in biological relationship and ancestry testing.
A dog trained in only one discipline.
Refers to a training exercise in which two subjects walk a straight line and then split into two different directions. When the canine is presented with a scent article from one of the subjects, the canine commences to trail and match the correct person to the scent article. Despite the contamination of scent from the other person on the trail the canine is still able to discriminate between scents and identify the correct subject.
propellant containing nitrocellulose as the major energetic material.
smokeless powder which contains nitrocellulose but does not contain nitroglycerine or nitroguanidine.
An evaluation of the canine team's ability to complete an exercise where the evaluator knows the outcome and the hander does not.
An evaluation of the canine team's ability to complete an exercise where the evaluator knows the outcome and the canine team does not.
An evaluation of the canine team's ability to complete an exercise where the evaluator knows the outcome and the handler does not.
An evaluation of the canine team's ability to complete an exercise where the evaluator knows the outcome and the canine team does not.
An evaluation of the canine team's ability to complete an exercise where the evaluator knows the outcome and the canine team does not.
An evaluation of the canine team's ability to complete an exercise where the evaluator knows the outcome and the canine team does not.
name for the most commonly used primer.
Discussion—It is composed primarily of lead styphnate, barium nitrate, and antimony sulfide.
A regularly irregular heart rhythm associated with changes in breathing, normal finding in the canine.
A regularly irregular heart rhythm associated with changes in breathing, normal finding in the canine.
The general physical location of the incident, including the scene and the surrounding area deemed significant to the process of the investigation and support areas.
Osseous, cartilaginous, and/or dental tissues.
a crystal in which all of the spaces in the crystal lattice are not occupied.
A representation of a friction skin image in which all pixels are white except for a 1-pixel-wide thinned black skeleton following the midpoint of each ridge. Also known as aridge tracing.
using a skimmer to acquire PII in an unauthorized manner.
a magnetic card reader, specifically when used for an illegal purpose.
The accidental discharge of a firearm upon closing of the action.
Slap fingerprints (slaps) are taken by simultaneously pressing the fingers of one hand(i.e., without the thumb) onto a scanner or fingerprint card. Slaps are also known as fourfinger simultaneous plain impressions (although if the person has more than four fingerson a hand, all of the fingers may be included in the slap image).
The compass direction (in degrees and accounting for declination) that a slope faces, viewed downslope.
Describes the relative ground surface uniformity (smooth = simple/S) or irregularity (complex/C) downslope through the site.
The ground surface inclination with respect to the horizontal plane; commonly called "slope". Make observations downslope to avoid errors from clinometer types.
thickened liquid solution of oxidizers and fuels blended with additional solid oxidizers and fuels with sensitizers.
Discussion—The main oxidizer is ammonium nitrate. Slurry explosives are more liquid-like than water gel explosives.
a transfer of paint resulting from contact between two objects; these transfers can consist of co-mingled particles from two or more sources, fragments, or contributions from a single source.
The airborne solid and liquid particulates and gases evolved when a material undergoes pyrolysis or combustion, together with the quantity of air that is entrained or otherwise mixed into the mass.
The condensed residue of suspended vapors and liquid products of incomplete combustion.
See backdraft.
A discoloration resulting from deposits of the solid constituents in smoke.
an explosive designed to deflagrate with minimal smoke production and used in ammunition as a propellant; can be single, double, or triple base.
Discussion—Some smokeless powders can detonate with proper initiation.
a propellant and low explosive composed of nitrocellulose and other organic and inorganic compounds
Combustion without flame, usually with incandescence and smoke.
Scar, (needle) mark, and tattoo information.
A protective device to permit dry firing without damage to the firing pin.
Extraction of an audio signal from an original recording in a way that disrupts thecontinuity and time record of the original recording.
Aerosol waxes used to coat the surface of snow impressions prior to casting.