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.
coalescence
coalescence
A model in population genetics to describe a process of how gene variants sampled from a population may have originated from a common ancestor.
Committee
Wildlife Forensic Biology
Date Added to Lexicon
Standard Source (Designation Number Title of Standard. Publisher, Place, Year.)
ANSI/ASB 111 Standard for Training in Mitochondrial DNA (mtDNA) Analysis for Taxonomic Identification . AAFS Academy Standards Board (ASB), 410 North 21st Street, Colorado Springs, CO, 2020.
Source link
Coating
Coating
a generic term for paint, lacquer, enamel, or other liquid or liquefiable material that is converted to a solid, protective, or decorative film or a combination of these types of films after application.
Committee
Trace Materials
Date Added to Lexicon
Standard Source (Designation Number Title of Standard. Publisher, Place, Year.)
ANSI/ASTM E1732 Standard Terminology Relating to Forensic Science. ASTM International, 100 Barr Harbor Drive, West Conshohocken, PA 19428, 2025.
Source link
Reprinted, with permission, from ASTM E1732 Standard Terminology Relating to Forensic Science, copyright ASTM International, 100 Barr Harbor Drive, West Conshohocken, PA 19428. A copy of the complete standard is available from ASTM International, https://www.astm.org
Coaxial Light
Coaxial Light
Illumination from the precise direction of the imaging lens (e.g. either through the lens or with a beam-splitter in front of the lens).
Committee
Footwear & Tire
Date Added to Lexicon
Technical Report/Other Source (Author, Title of report. Publisher, Year.)
ASB TR 097, Terminology Used for Forensic Footwear and Tire Evidence. AAFS Academy Standards Board (ASB), 410 North 21st Street, Colorado Springs, CO 80904, 2019.
Source link
Coaxial Lighting
Coaxial Lighting
Illumination from the precise direction of the imaging lens (e.g. either through the lens or with abeam-splitter in front of the lens).
Committee
Footwear & Tire
Date Added to Lexicon
Standard Source (Designation Number Title of Standard. Publisher, Place, Year.)
ANSI/ASB Best Practice Recommendation 052 Best Practice Recommendation for the Detection and Collection of Footwear and Tire Impression Evidence. AAFS Academy Standards Board (ASB), 410 North 21st Street, Colorado Springs, CO 80904, 2022.
Source link
Cocaine
Cocaine
either d- or l- cocaine; it should be noted that l-cocaine is the naturally occurring isomer found in the coca plant.
Committee
Seized Drugs
Date Added to Lexicon
Standard Source (Designation Number Title of Standard. Publisher, Place, Year.)
ANSI/ASTM E1732 Standard Terminology Relating to Forensic Science. ASTM International, 100 Barr Harbor Drive, West Conshohocken, PA 19428, 2025.
Source link
Reprinted, with permission, from ASTM E1732 Standard Terminology Relating to Forensic Science, copyright ASTM International, 100 Barr Harbor Drive, West Conshohocken, PA 19428. A copy of the complete standard is available from ASTM International, https://www.astm.org
Code
Code
A standard that is an extensive compilation of provisions covering broad subject matter or that is suitable for adoption into law independently of other codes and standards.
Committee
Fire & Explosion Investigation
Date Added to Lexicon
Standard Source (Designation Number Title of Standard. Publisher, Place, Year.)
NFPA 921:2021 Guide for Fire and Explosion Investigations. The National Fire Protection Association (NFPA), 1 Batterymarch Park, Quincy, MA, 2021.
Source link
Codec
Codec
an algorithm to encode and decode digital data, typically to reduce the amount of data for transmission or storage.
Discussion—A codec is not a storage format, but may be required to interpret stored data.
Committee
Interdisciplinary
Date Added to Lexicon
Standard Source (Designation Number Title of Standard. Publisher, Place, Year.)
ANSI/ASTM E1732 Standard Terminology Relating to Forensic Science. ASTM International, 100 Barr Harbor Drive, West Conshohocken, PA 19428, 2025.
Source link
Reprinted, with permission, from ASTM E1732 Standard Terminology Relating to Forensic Science, copyright ASTM International, 100 Barr Harbor Drive, West Conshohocken, PA 19428. A copy of the complete standard is available from ASTM International, https://www.astm.org
Codec
Codec
A codec is a computer program that encodes and decodes a data signal, usually in acompressed format.
Committee
Interdisciplinary
Date Added to Lexicon
Standard Source (Designation Number Title of Standard. Publisher, Place, Year.)
ANSI/NIST-ITL 1-2011 Update:2015 Data Format for the Interchange of Fingerprint, Facial & Other Biometric Information. ANSI/National Institute of Standards and Technology, 2011.
Source link
Codec
Codec
Algorithm designed to encode or decode a stream of digital audio data.
Committee
Speaker Recognition
Date Added to Lexicon
Standard Source (Designation Number Title of Standard. Publisher, Place, Year.)
AES 76-2022 AES Standard for Audio Forensics - Speech Collection Guidelines for Speaker Recognition: Interviewing at a Temporary Location. Audio Engineering Society, Inc., 2022.
Source link
Codec Format
Codec Format
A codec format is the data structure produced by a codec.
Committee
Interdisciplinary
Date Added to Lexicon
Standard Source (Designation Number Title of Standard. Publisher, Place, Year.)
ANSI/NIST-ITL 1-2011 Update:2015 Data Format for the Interchange of Fingerprint, Facial & Other Biometric Information. ANSI/National Institute of Standards and Technology, 2011.
Source link
Coercion Training
Coercion Training
Coercion deals with compliance induced by physical or mental pressure. Examples may include use of force, threats, or intimidation.
Committee
Dogs & Sensors
Date Added to Lexicon
Technical Report/Other Source (Author, Title of report. Publisher, Year.)
ANSI/Academy Standards Board (ASB), Crime Scene/Death Investigation - Dogs and Sensors - Terms and Definitions. AAFS Academy Standards Board (ASB), 410 North 21st Street, Colorado Springs, CO 80904, 2017.
Source link
Cognitive Image Analysis
Cognitive Image Analysis
in image and video analysis, a process used to extract visual information from an image by human evaluation.
Committee
Interdisciplinary
Date Added to Lexicon
Standard Source (Designation Number Title of Standard. Publisher, Place, Year.)
ANSI/ASTM E1732 Standard Terminology Relating to Forensic Science. ASTM International, 100 Barr Harbor Drive, West Conshohocken, PA 19428, 2025.
Source link
Reprinted, with permission, from ASTM E1732 Standard Terminology Relating to Forensic Science, copyright ASTM International, 100 Barr Harbor Drive, West Conshohocken, PA 19428. A copy of the complete standard is available from ASTM International, https://www.astm.org
Coherence Scanning Interferometry
Coherence Scanning Interferometry
Surface topography measurement method wherein the localization of interference fringes during ascan of optical path length provides a means to determine a surface topography map.
Committee
Firearms & Toolmarks
Date Added to Lexicon
Standard Source (Designation Number Title of Standard. Publisher, Place, Year.)
ANSI/ASB 061 Firearms and Toolmarks 3D Measurement Systems and Measurement Quality Control. AAFS Academy Standards Board (ASB), 410 North 21st Street, Colorado Springs, CO 80904, 2021.
Source link
Coherent (Rayleigh) Scatter Peaks
Coherent (Rayleigh) Scatter Peaks
spectral artifacts that result from elastic scattering of the tube target characteristic X-rays by the sample.
Discussion—Because no energy is lost in elastic scattering, coherent scatter peaks occur at the same energies as the tube target characteristic X-rays.
Committee
Trace Materials
Date Added to Lexicon
Standard Source (Designation Number Title of Standard. Publisher, Place, Year.)
ANSI/ASTM E1732 Standard Terminology Relating to Forensic Science. ASTM International, 100 Barr Harbor Drive, West Conshohocken, PA 19428, 2025.
Source link
Reprinted, with permission, from ASTM E1732 Standard Terminology Relating to Forensic Science, copyright ASTM International, 100 Barr Harbor Drive, West Conshohocken, PA 19428. A copy of the complete standard is available from ASTM International, https://www.astm.org
coincidental peripheral printing
coincidental peripheral printing
Printing resulting from an impression in an unintended printing area, often on the periphery of a stamp. This may be due to the manufacturing process or the stamping technique.
Committee
Forensic Document Examination
Date Added to Lexicon
Standard Source (Designation Number Title of Standard. Publisher, Place, Year.)
ANSI/ASB 117 Standard for Examination of Stamping Devices and Stamp Impressions. AAFS Academy Standards Board (ASB), 410 North 21st Street, Colorado Springs, CO, 2020.
Source link
Color Contrast
Color Contrast
the degree of visual difference that is evident between one soil color compared with another in close proximity.
Discussion—Within this practice, color contrast refers to color difference between evidentiary soil samples.
Committee
Trace Materials
Date Added to Lexicon
Standard Source (Designation Number Title of Standard. Publisher, Place, Year.)
ANSI/ASTM E1732 Standard Terminology Relating to Forensic Science. ASTM International, 100 Barr Harbor Drive, West Conshohocken, PA 19428, 2025.
Source link
Reprinted, with permission, from ASTM E1732 Standard Terminology Relating to Forensic Science, copyright ASTM International, 100 Barr Harbor Drive, West Conshohocken, PA 19428. A copy of the complete standard is available from ASTM International, https://www.astm.org
Color contrast classes
Color contrast classes
degree of color distinction (color contrast) between colors within a soil are categorized as faint, distinct and prominent.
Discussion—Within this practice, these contrast classes are used to describe the degree of color distinction between two evidentiary soil samples, whereas the United States Department of Agriculture – National Resource Conservation Service – National Cooperative Soil Survey (NCSS) uses these contrast classes to describe color distinction within soil horizons. Faint color contrast is evident only on close examination. Distinct color contrast is readily seen but contrasts only moderately with the color to which it is compared. Prominent indicates colors which contrast strongly with the color to which it is compared; prominent colors are commonly the most obvious color feature of the section described. The NCSS thresholds between faint and distinct color contrast (1) are adapted as exclusion criteria in forensic comparisons of soil.
Committee
Trace Materials
Date Added to Lexicon
Standard Source (Designation Number Title of Standard. Publisher, Place, Year.)
ANSI/ASTM E1732 Standard Terminology Relating to Forensic Science. ASTM International, 100 Barr Harbor Drive, West Conshohocken, PA 19428, 2025.
Source link
Reprinted, with permission, from ASTM E1732 Standard Terminology Relating to Forensic Science, copyright ASTM International, 100 Barr Harbor Drive, West Conshohocken, PA 19428. A copy of the complete standard is available from ASTM International, https://www.astm.org
Color Range
Color Range
See gamut
Committee
Facial & Iris Identification
Date Added to Lexicon
Standard Source (Designation Number Title of Standard. Publisher, Place, Year.)
ANSI/ASTM E1732 Standard Terminology Relating to Forensic Science. ASTM International, 100 Barr Harbor Drive, West Conshohocken, PA 19428, 2025.
Source link
Reprinted, with permission, from ASTM E1732 Standard Terminology Relating to Forensic Science, copyright ASTM International, 100 Barr Harbor Drive, West Conshohocken, PA 19428. A copy of the complete standard is available from ASTM International, https://www.astm.org
Combustible
Combustible
any substance that will burn, regardless of its autoignition temperature, or whether it is a solid, liquid or gas.
Committee
Ignitable Liquids, Explosives & Gunshot Residue
Date Added to Lexicon
Standard Source (Designation Number Title of Standard. Publisher, Place, Year.)
ANSI/ASTM E1732 Standard Terminology Relating to Forensic Science. ASTM International, 100 Barr Harbor Drive, West Conshohocken, PA 19428, 2025.
Source link
Reprinted, with permission, from ASTM E1732 Standard Terminology Relating to Forensic Science, copyright ASTM International, 100 Barr Harbor Drive, West Conshohocken, PA 19428. A copy of the complete standard is available from ASTM International, https://www.astm.org
Combustible
Combustible
capable of undergoing combustion.
Committee
Interdisciplinary
Date Added to Lexicon
Standard Source (Designation Number Title of Standard. Publisher, Place, Year.)
ANSI/ASTM E1732 Standard Terminology Relating to Forensic Science. ASTM International, 100 Barr Harbor Drive, West Conshohocken, PA 19428, 2025.
Source link
Reprinted, with permission, from ASTM E1732 Standard Terminology Relating to Forensic Science, copyright ASTM International, 100 Barr Harbor Drive, West Conshohocken, PA 19428. A copy of the complete standard is available from ASTM International, https://www.astm.org
Combustible
Combustible
Capable of undergoing combustion.
Committee
Fire & Explosion Investigation
Date Added to Lexicon
Standard Source (Designation Number Title of Standard. Publisher, Place, Year.)
NFPA 921:2021 Guide for Fire and Explosion Investigations. The National Fire Protection Association (NFPA), 1 Batterymarch Park, Quincy, MA, 2021.
Source link
Combustible Dust
Combustible Dust
Any finely divided solid material that is 420 microns or smaller in diameter (material passing a U.S. No. 40 Standard Sieve) and presents a fire or explosion hazard when dispersed and ignited in air.
Committee
Fire & Explosion Investigation
Date Added to Lexicon
Standard Source (Designation Number Title of Standard. Publisher, Place, Year.)
NFPA 654:2020 Standard for the Prevention of Fire and Dust Explosions from the Manufacturing, Processing, and Handling of Combustible Particulate Solids. The National Fire Protection Association (NFPA), 1 Batterymarch Park, Quincy, MA, 2020.
Source link
Combustible Gas Indicator
Combustible Gas Indicator
An instrument that samples air and indicates whether there are ignitible vapors or gases present.
Committee
Fire & Explosion Investigation
Date Added to Lexicon
Standard Source (Designation Number Title of Standard. Publisher, Place, Year.)
NFPA 921:2021 Guide for Fire and Explosion Investigations. The National Fire Protection Association (NFPA), 1 Batterymarch Park, Quincy, MA, 2021.
Source link
Combustible Liquid
Combustible Liquid
See Ignitable Liquid
Committee
Ignitable Liquids, Explosives & Gunshot Residue
Date Added to Lexicon
Standard Source (Designation Number Title of Standard. Publisher, Place, Year.)
ANSI/ASTM E1732 Standard Terminology Relating to Forensic Science. ASTM International, 100 Barr Harbor Drive, West Conshohocken, PA 19428, 2025.
Source link
Reprinted, with permission, from ASTM E1732 Standard Terminology Relating to Forensic Science, copyright ASTM International, 100 Barr Harbor Drive, West Conshohocken, PA 19428. A copy of the complete standard is available from ASTM International, https://www.astm.org
Combustible Liquid
Combustible Liquid
Any liquid that has a closed-cup flash point at or above 37.8C (100F). (See also 3.3.89, Flammable Liquid.)
Committee
Fire & Explosion Investigation
Date Added to Lexicon
Standard Source (Designation Number Title of Standard. Publisher, Place, Year.)
NFPA 921:2021 Guide for Fire and Explosion Investigations. The National Fire Protection Association (NFPA), 1 Batterymarch Park, Quincy, MA, 2021.
Source link
Combustion
Combustion
a usually rapid chemical process (such as oxidation) that produces heat and usually light.
Committee
Interdisciplinary
Date Added to Lexicon
Standard Source (Designation Number Title of Standard. Publisher, Place, Year.)
ANSI/ASTM E1732 Standard Terminology Relating to Forensic Science. ASTM International, 100 Barr Harbor Drive, West Conshohocken, PA 19428, 2025.
Source link
Reprinted, with permission, from ASTM E1732 Standard Terminology Relating to Forensic Science, copyright ASTM International, 100 Barr Harbor Drive, West Conshohocken, PA 19428. A copy of the complete standard is available from ASTM International, https://www.astm.org
Combustion
Combustion
A chemical process of oxidation that occurs at a rate fast enough to produce heat and usually light in the form of either a glow or flame.
Committee
Fire & Explosion Investigation
Date Added to Lexicon
Standard Source (Designation Number Title of Standard. Publisher, Place, Year.)
NFPA 921:2021 Guide for Fire and Explosion Investigations. The National Fire Protection Association (NFPA), 1 Batterymarch Park, Quincy, MA, 2021.
Source link
Combustion Product
Combustion Product
the heat, gases, volatilized liquids and solids, particulate matter, and ash generated by combustion.
Discussion—Combustion products are the result of complete or incomplete combustion, but not thermal decomposition (see pyrolysis).
Committee
Ignitable Liquids, Explosives & Gunshot Residue
Date Added to Lexicon
Standard Source (Designation Number Title of Standard. Publisher, Place, Year.)
ANSI/ASTM E1732 Standard Terminology Relating to Forensic Science. ASTM International, 100 Barr Harbor Drive, West Conshohocken, PA 19428, 2025.
Source link
Reprinted, with permission, from ASTM E1732 Standard Terminology Relating to Forensic Science, copyright ASTM International, 100 Barr Harbor Drive, West Conshohocken, PA 19428. A copy of the complete standard is available from ASTM International, https://www.astm.org
Combustion Products
Combustion Products
The heat, gases, volatilized liquids and solids, particulate matter, and ash generated by combustion.
Committee
Fire & Explosion Investigation
Date Added to Lexicon
Standard Source (Designation Number Title of Standard. Publisher, Place, Year.)
NFPA 921:2021 Guide for Fire and Explosion Investigations. The National Fire Protection Association (NFPA), 1 Batterymarch Park, Quincy, MA, 2021.
Source link
Comma-Separated Value File Csv
Comma-Separated Value File Csv
A simple file format for tabular data where individual values are separated by a comma (or other designated delimiter).
Committee
Firearms & Toolmarks
Date Added to Lexicon
Standard Source (Designation Number Title of Standard. Publisher, Place, Year.)
ANSI/ASB 062 Standard for Topography Comparison Software for Toolmark Analysis. AAFS Academy Standards Board (ASB), 410 North 21st Street, Colorado Springs, CO 80904, 2021.
Source link
commingling
commingling
The intermixing of biological material representing multiple individuals.
Committee
Forensic Anthropology
Date Added to Lexicon
Standard Source (Designation Number Title of Standard. Publisher, Place, Year.)
ANSI/ASB 146 Standard for Resolving Commingled Remains in Forensic Anthropology . AAFS Academy Standards Board (ASB), 410 North 21st Street, Colorado Springs, CO , 2021.
Source link
Commonly Associated Particles
Commonly Associated Particles
particles have compositions that are also commonly found in environmental particles from numerous sources.
Discussion—When present in addition to particles that are characteristic of, or consistent with, GSR, or both, these particles can be of use in the interpretation of a population of particles and, consequently, the likelihood that that population is GSR. In isolation, however, such particles have little use in examinations for GSR.
Committee
Ignitable Liquids, Explosives & Gunshot Residue
Date Added to Lexicon
Standard Source (Designation Number Title of Standard. Publisher, Place, Year.)
ANSI/ASTM E1732 Standard Terminology Relating to Forensic Science. ASTM International, 100 Barr Harbor Drive, West Conshohocken, PA 19428, 2025.
Source link
Reprinted, with permission, from ASTM E1732 Standard Terminology Relating to Forensic Science, copyright ASTM International, 100 Barr Harbor Drive, West Conshohocken, PA 19428. A copy of the complete standard is available from ASTM International, https://www.astm.org
Companding Algorithm
Companding Algorithm
An algorithm that allows signals with a large dynamic range to be transmitted overfacilities with a smaller dynamic range. It is used in telephony (see -law and A-law)and some other types of communications
Committee
Interdisciplinary
Date Added to Lexicon
Standard Source (Designation Number Title of Standard. Publisher, Place, Year.)
ANSI/NIST-ITL 1-2011 Update:2015 Data Format for the Interchange of Fingerprint, Facial & Other Biometric Information. ANSI/National Institute of Standards and Technology, 2011.
Source link
comparative medical imaging
comparative medical imaging
An identification technique involving the direct comparison of antemortem and postmortem medical imaging to include radiographs, computed tomography (CT), magnetic resonance imaging (MRI) and other modalities.
Committee
Forensic Anthropology
Date Added to Lexicon
Standard Source (Designation Number Title of Standard. Publisher, Place, Year.)
ANSI/ASB 148 Standard for Personal Identification in Forensic Anthropology. AAFS Academy Standards Board (ASB), 410 North 21st Street, Colorado Springs, CO, 2024.
Source link
comparative report
comparative report
a written report that includes an assessment of the significance of the comparative results from the analysis of two or more items to determine whether the items could have originated from the same or different sources.
Committee
Trace Materials
Date Added to Lexicon
Standard Source (Designation Number Title of Standard. Publisher, Place, Year.)
ANSI/ASTM E1732 Standard Terminology Relating to Forensic Science. ASTM International, 100 Barr Harbor Drive, West Conshohocken, PA 19428, 2025.
Source link
Reprinted, with permission, from ASTM E1732 Standard Terminology Relating to Forensic Science, copyright ASTM International, 100 Barr Harbor Drive, West Conshohocken, PA 19428. A copy of the complete standard is available from ASTM International, https://www.astm.org
comparative statement
comparative statement
A qualitative conclusion of any comparison performed to assess the degree of similarity or difference between DNA data (e.g., inclusion or exclusion).
Committee
Human Forensic Biology
Date Added to Lexicon
Standard Source (Designation Number Title of Standard. Publisher, Place, Year.)
ANSI/ASB 139 Reporting DNA Conclusions. AAFS Academy Standards Board (ASB), 410 North 21st Street, Colorado Springs, CO, 2024.
Source link
Comparison
Comparison
The process of examining two or more DNA data sets to assess the degree of similarity or difference.
Committee
Human Forensic Biology
Date Added to Lexicon
Standard Source (Designation Number Title of Standard. Publisher, Place, Year.)
ANSI/ASB 175 Standard for Interpreting, Comparing and Reporting DNA Test Results Associated with Failed Controls and Contamination Events . AAFS Academy Standards Board (ASB), 410 North 21st Street, Colorado Springs, CO , 2024.
Source link
Comparison
Comparison
The process of examining two or more DNA data sets to assess the degree of similarity or difference.
Committee
Human Forensic Biology
Date Added to Lexicon
Standard Source (Designation Number Title of Standard. Publisher, Place, Year.)
ANSI/ASB 123 Standard for Routine Internal Evaluation of a Laboratory’s DNA Interpretation and Comparison Protocol. AAFS Academy Standards Board (ASB), 410 North 21st Street, Colorado Springs, CO, 2024.
Source link
comparison
comparison
Consists of an examination of correspondence or non-correspondence between items, unknown and known.
Committee
Footwear & Tire
Date Added to Lexicon
Standard Source (Designation Number Title of Standard. Publisher, Place, Year.)
ANSI/ASB 137 Standard for Examination and Documentation of Footwear and Tire Impression Evidence. AAFS Academy Standards Board (ASB), 410 North 21st Street, Colorado Springs, CO, 2023.
Source link
Comparison
Comparison
The process of examining two or more DNA data sets to assess the degree of similarity or difference.
Committee
Human Forensic Biology
Date Added to Lexicon
Standard Source (Designation Number Title of Standard. Publisher, Place, Year.)
ANSI/ASB 040 Standard for Forensic DNA Interpretation and Comparison Protocols. AAFS Academy Standards Board (ASB), 410 North 21st Street, Colorado Springs, CO 80904, 2019.
Source link
comparison (phase of the examination process)
comparison (phase of the examination process)
The search for and detection of similarities and dissimilarities in observed data between friction ridge impressions.
Committee
Friction Ridge
Date Added to Lexicon
Standard Source (Designation Number Title of Standard. Publisher, Place, Year.)
ANSI/ASB 015 Standard for Examining Friction Ridge Impressions. AAFS Academy Standards Board (ASB), 410 North 21st Street, Colorado Springs, CO, 2024.
Source link
comparison (phase of the examination process)
comparison (phase of the examination process)
The search for and detection of similarities and dissimilarities in observed data between friction ridge impressions.
Committee
Friction Ridge
Date Added to Lexicon
Standard Source (Designation Number Title of Standard. Publisher, Place, Year.)
ANSI/ASB Best Practice Recommendation 166 Best Practice Recommendation for Comparison and Evaluation of Friction Ridge Impressions. AAFS Academy Standards Board (ASB), 410 North 21st Street, Colorado Springs, CO, 2024.
Source link
comparison (phase of the examination process)
comparison (phase of the examination process)
The search for and detection of similarities and dissimilarities in observed data between friction ridge impressions.
Committee
Friction Ridge
Date Added to Lexicon
Standard Source (Designation Number Title of Standard. Publisher, Place, Year.)
ANSI/ASB Best Practice Recommendation 165 Best Practice Recommendation for Analysis of Friction Ridge Impressions. AAFS Academy Standards Board (ASB), 410 North 21st Street, Colorado Springs, CO, 2024.
Source link
Comparison Algorithm
Comparison Algorithm
A series of computational steps which seeks to assess both the level of geometric similarity (similarity of toolmarks) and the degree of certainty that the observed similarity results from a common origin. A comparison algorithm makes use of a scoring function or similarity score.
Committee
Firearms & Toolmarks
Date Added to Lexicon
Standard Source (Designation Number Title of Standard. Publisher, Place, Year.)
ANSI/ASB 062 Standard for Topography Comparison Software for Toolmark Analysis. AAFS Academy Standards Board (ASB), 410 North 21st Street, Colorado Springs, CO 80904, 2021.
Source link
Comparison microscope
Comparison microscope
a system of two microscopes positioned side-by-side and connected via an optical bridge so that two specimens are examined simultaneously in a single field of view in either transmitted or reflected light.
Committee
Trace Materials
Date Added to Lexicon
Standard Source (Designation Number Title of Standard. Publisher, Place, Year.)
ANSI/ASTM E1732 Standard Terminology Relating to Forensic Science. ASTM International, 100 Barr Harbor Drive, West Conshohocken, PA 19428, 2025.
Source link
Reprinted, with permission, from ASTM E1732 Standard Terminology Relating to Forensic Science, copyright ASTM International, 100 Barr Harbor Drive, West Conshohocken, PA 19428. A copy of the complete standard is available from ASTM International, https://www.astm.org
Comparison Sample
Comparison Sample
fire debris, (1) a sample of material collected from a fire scene which is, to the best of the collector's knowledge, similar with respect to relevant characteristics to a sample suspected of containing ignitable substance, but which is not expected to contain an ignitable substance; (2) a sample of suspected ignitable substance submitted for the purpose of comparing with any ignitable substance separated from a debris sample.
Discussion—A comparison sample should not be confused with a control sample. For example, a comparison sample might include unburned carpet or flooring that meets the requirements in (1).
Discussion—Although, in theory, the use of comparison samples can help clarify the presence of a suspected inherent ignitable liquid, the presence of an ignitable liquid in a comparison sample does not necessarily mean it is inherent to the material.
Committee
Interdisciplinary
Date Added to Lexicon
Standard Source (Designation Number Title of Standard. Publisher, Place, Year.)
ANSI/ASTM E1732 Standard Terminology Relating to Forensic Science. ASTM International, 100 Barr Harbor Drive, West Conshohocken, PA 19428, 2025.
Source link
Reprinted, with permission, from ASTM E1732 Standard Terminology Relating to Forensic Science, copyright ASTM International, 100 Barr Harbor Drive, West Conshohocken, PA 19428. A copy of the complete standard is available from ASTM International, https://www.astm.org
Comparison Software
Comparison Software
Software that implements a comparison algorithm and may also include database, search, and visualization functionality.
Committee
Firearms & Toolmarks
Date Added to Lexicon
Standard Source (Designation Number Title of Standard. Publisher, Place, Year.)
ANSI/ASB 062 Standard for Topography Comparison Software for Toolmark Analysis. AAFS Academy Standards Board (ASB), 410 North 21st Street, Colorado Springs, CO 80904, 2021.
Source link
Compensator
Compensator
any variety of optical devices that can be placed in the light path of a polarized light microscope to introduce known, fixed or variable retardation in a specific vibration direction; the retardation and sign of elongation of the fiber can then be determined.
Committee
Trace Materials
Date Added to Lexicon
Standard Source (Designation Number Title of Standard. Publisher, Place, Year.)
ANSI/ASTM E1732 Standard Terminology Relating to Forensic Science. ASTM International, 100 Barr Harbor Drive, West Conshohocken, PA 19428, 2025.
Source link
Reprinted, with permission, from ASTM E1732 Standard Terminology Relating to Forensic Science, copyright ASTM International, 100 Barr Harbor Drive, West Conshohocken, PA 19428. A copy of the complete standard is available from ASTM International, https://www.astm.org
Compensator, Full-Wave (or red plate)
Compensator, Full-Wave (or red plate)
a compensator (usually a plate of gypsum, selenite or quartz) that introduces a fixed retardation between 530 to 550nm (approximately the retardation of the first order red color on the Michel-Levy chart).
Committee
Trace Materials
Date Added to Lexicon
Standard Source (Designation Number Title of Standard. Publisher, Place, Year.)
ANSI/ASTM E1732 Standard Terminology Relating to Forensic Science. ASTM International, 100 Barr Harbor Drive, West Conshohocken, PA 19428, 2025.
Source link
Reprinted, with permission, from ASTM E1732 Standard Terminology Relating to Forensic Science, copyright ASTM International, 100 Barr Harbor Drive, West Conshohocken, PA 19428. A copy of the complete standard is available from ASTM International, https://www.astm.org
Compensator, Quarter-Wave
Compensator, Quarter-Wave
a compensator (usually a mica plate) that introduces a fixed retardation between ~137–147nm (approximately the retardation of first-order gray on the Michel-Levy chart).
Committee
Trace Materials
Date Added to Lexicon
Standard Source (Designation Number Title of Standard. Publisher, Place, Year.)
ANSI/ASTM E1732 Standard Terminology Relating to Forensic Science. ASTM International, 100 Barr Harbor Drive, West Conshohocken, PA 19428, 2025.
Source link
Reprinted, with permission, from ASTM E1732 Standard Terminology Relating to Forensic Science, copyright ASTM International, 100 Barr Harbor Drive, West Conshohocken, PA 19428. A copy of the complete standard is available from ASTM International, https://www.astm.org