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.
Written documentation maintained by the laboratory including laboratory policies, technical protocols and methods for specific forensic analyses (see also standard operating procedure).
A qualified second party's evaluation of reports, notes, data, and other documentation to ensure there is appropriate and sufficient support for the actions, results, conclusions, opinions, and interpretations.
Also referenced in ANSI/ASB 019 Wildlife Forensics General Standards, ANSI/ASB Technical Report 025, Crime Scene/Death Investigation - Dogs and Sensors - Terms and Definitions, ANSI/ASB 063 Implementation of 3D Technologies in Forensic Firearm and Toolmark Comparison Laboratories, ANSI/ASB 142-22 Best Practice Recommendations for the Resolution of Conflicts in Friction Ridge Examination, ANSI/ASTM E3392-24 Standard Guide for Forensic Physical Fit Examination.
An individual with the knowledge/expertise to conduct the technical review to determine if theappropriate examinations have been performed, support the results/conclusions of thedevelopment and/or deployment validations, and that the reported results are consistent with therecorded data and are within the scope of testing.
Used to describe the type of forensic DNA analysis performed in the laboratory, such as SNP, STR, YSTR, or mitochondrial DNA.
The general consistence with which the animal behaves. Broad classes of temperament appear to be heritable. OutgoingBehavior of the canine characterized by seeking human interaction. StableBehavior of the canine that is consistent over time, place and environmental conditions.
The general consistence with which the animal behaves. Broad classes of temperament appear to be heritable. OutgoingBehavior of the canine characterized by seeking human interaction. StableBehavior of the canine that is consistent over time, place and environmental conditions.
The degree of sensible heat of a body as measured by a thermometer or similar instrument.
The quality of a canine to persist at a task regardless of the environmental distractions or task difficulty.
The quality of a canine to persist at a task regardless of the environmental distractions or task difficulty.
Other terms specific to firearms, such as rifle, shotgun, pistol, revolver, firearm, single action, double action, sear, and cock are described in Association of Firearm and Tool Mark Examiners, Glossary [7] and Glossary-SAAMI [1]23].
The determination, by technical means, of properties, performance or elements of materials, products, services, systems, or environments, which may involve application of established scientific principles and procedures. Testing typically applies to materials, products or processes.
To discharge a firearm in a laboratory or controlled setting in order to obtain representative bulletsand cartridge cases for comparison or analysis, or to determine functionality of the firearm.
An impression made from a known footwear or tire used as an aid for comparison purposes.
A term intended to encompass any report containing the description of items submitted to a laboratory, as well as any results of testing and examinations that may have occurred.
See plume
The increase in length, volume, or surface area of a body with rise in temperature.
The properties of a material that characterize its rate of surface temperature rise when exposed to heat; related to the product of the material's thermal conductivity (k), its density (_), and its heat capacity (c).
The branch of physics that deals with the relationship between heat and other forms of energy.
The study of the science, methodology, and practice of temperature measurement.
Plastic materials that soften and melt under exposure to heat and can reach a flowable state.
Plastic materials that are hardened into a permanent shape in the manufacturing process and are not commonly subject to softening when heated; typically form char in a fire.
An impression made on surfaces such as soil, sand, snow or mud with dimensions of length, width, and depth.
DetectionThe minimum and maximum concentration of a chemical vapor that can be detected by a canine or an instrument. BehavioralThe level of stimulation above or below which learning and/or performance is impaired.
Graphic representation of the events in a fire incident displayed in chronological order.
the most distal end of a hair shaft.
Any solid biological specimen that is generally weighed for analysis (e.g., brain, liver, muscle, hair, bone, meconium).
Organization responsible for recovering tissues from tissue donors.
See vaccine titer.
See vaccine titer.
The allowable range of deviation from the class resolution, symmetric around the classresolution value. For PIV single fingerprint scanners with the class resolution of 500 ppi,the tolerance is 2%. For all scanners other than PIV, the tolerance is 1%.
A measurement of an objects surface geometry. Topographic data may be one, two, or three dimensional.
1D topography data is also known as a Linear Profile. A linear profile with n points shall be represented as a function of a single coordinate where at each point along a single axis (xi) (where i=1,...,n) there is a measured height (zi). Both xi and zi are measured in standard units (e.g., micrometers). An example of a linear profile is a cross-section through a striated toolmark (e.g., bullet land area); where xi is a spatial position measured in micrometers and zi is the corresponding height of the striation profile measured in micrometers.
2D topography data is also known as a Planar Image. An n-by-m planar image I shall be represented as a function of two coordinates where at each point (xi, yj) (where i=1,...,n; j=1,...,m) there is a measured surface color or intensity denoted I(xi, yj). An example of 2D topographic data is an image taken through a comparison microscope; where each point I (xi, yj) is the RGB (red, green, blue) color value measured at the specified (xi, yj) position. The measured color or intensity is a function of the surface geometry and the environmental conditions (e.g., light position). Although reference scales may be included in the collected image, the points (xi, yj) may or may not be measured in standard units (e.g., micrometers).
3D topography data is also known as a Heightmap. An n-by-m heightmap H shall be represented asa function of two coordinates where at each point (xi, yj) (where i=1,...,n; j=1,...,m) there is ameasured surface height zi,j = H(xi, yj). All three coordinates xi, yj, and zi,j are measured in standardunits (e.g., micrometers). The surface H is a 1-to-1 representation of the actual object. An exampleof 3D topographic data is a primer surface measured using a confocal microscope; where each pointH(xi, yj) represents the surface height (in micrometers) measured at the specified (xi, yj) position. 3Ddata captured on hardware compliant with ANSI/ASB Standard 061, Firearm and Toolmarks 3DMeasurement Systems and Measurement Quality Control can be used in virtual comparisonmicroscopy.
The branching structure of a phylogram
A fire scene where a fire continued to burn until most combustibles were consumed and the fire self-extinguished due to a lack of fuel or was extinguished when the fuel load was reduced by burning and there was sufficient suppression agent application to extinguish the fire.
An individual (however named) who provides factual information and/or interpretive opinions related to the results of toxicological tests for court or investigative purposes. May be further defined by role [e.g., Toxicologist (General), Toxicologist (Alcohol), Toxicologist (Breath Alcohol)]
A minimal amount of target odor.
The property of a result of a measurement or value of a standard whereby it can be related with a stated uncertainty and to appropriate standards, generally international or national standards, through an unbroken chain of comparisons. The unbroken chain of comparisons is called a traceability chain. Traceability of a chemical species is frequently of equal or greater importance than the traceability of the calibration of the instruments used in the analysis.
A path associated with a single read/write head on a data medium.
The propensity or learned ability of a canine to methodically follow odor/scent on the ground (human/ground disturbance) by working the canine close to the pathway. Canines are not typically pre-scented on an object.
The propensity or learned ability of a canine to methodically follow odor/scent on the ground (human/ground disturbance) by working the canine close to the pathway. Canines are not typically pre-scented on an object.
The scent pathway left by an individual moving.
The scent pathway left by an individual moving.