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.
in video analysis, the transformation of one television system signal to another, for example, National Television System Committee (NTSC) to Phase Alternating Line (PAL).
Investigator's tools and equipment that every investigator must carry.
Written documentation maintained by the laboratory including laboratory policies, technical protocols and methods for specific forensic analyses (see also technical procedure).
Written analytical procedure that describes how to perform certain organization activities
a method published by a recognized international, regional, or national standard development organization (for example, ASTM, ASB, AOAC, etc.).
natural fibers or cut lengths from filaments.
a 5-bit binary sequence, or equivalent ASCII character, used to signify the beginning of track data. (See ISO/IEC 7813:2006.)
A largely unconscious defensive response in a canine to sudden or threatening stimuli or perceived stimuli.
A largely unconscious defensive response to sudden or threatening stimuli or perceived stimuli.
see static headspace sampling (E1388), and static headspace concentration (E3189).
an extraction technique in which a portion of the headspace vapors is removed from the sample container.
an extraction technique in which a portion of the headspace vapors is removed from the sample container and concentrated onto an adsorbent medium.
an extraction technique in which a portion of the headspace vapors is removed from the sample container and concentrated onto an adsorbent medium.
an extraction technique in which a portion of the headspace vapors is removed from the sample container.
the solid adsorbent coating layer of a TLC plate.
The probability of obtaining the observed resultor a more exaggerated oneif the null hypothesis of no effect was true.
A quantitative statement that provides a measure of support for the comparison performed (e.g., random match probability, likelihood ratio).
A Category 2 scoring function.
a microscope containing two separate optical paths, one for each eye, giving a three-dimensional view of a specimen.
The act of producing a snoring sound [1].
The act of producing a snoring sound.
A friction ridge image created by combining images that were separately captured.
1) Chance, or random variation 2) in DNA testing, refers to random sampling error from extracts containing low levels of DNA and/or random variation in selection of alleles amplified at a particular locus.
Describes 1) chance, or random variation 2) in DNA testing, refers to random sampling error from extracts containing low levels of DNA and/or random variation in selection of alleles amplified at a particular locus.
Changes in a DNA profile that generally occur when suboptimal or limiting quantities of DNA are tested. This may be due to sampling variation (e.g., pipetting) of the target DNA that goes into the polymerase chain reaction (PCR) and/or random events between primers and target DNA during PCR amplification. The effects may be observed at one or more loci, and include: 1) peak height imbalance of sister alleles in a heterozygous pair; 2) loss of data (referred to as 'allele drop out' when one or more alleles are missing at a locus and 'locus drop out' when all alleles are missing from a locus); 3) allele drop-in [allelic peak(s) in an electropherogram that are not reproducible]; and 4) elevated stutter peaks (a non-allelic peak in the stutter position exceeding the stutter expectation of the laboratory).
Changes in a DNA profile that generally occur when suboptimal or limiting quantities of DNA are tested. This may be due to sampling variation (e.g., pipetting) of the target DNA that goes into the ANSI/ASB Standard 020, 1st Ed. 2018 2 polymerase chain reaction (PCR) and/or random events between primers and target DNA during PCR amplification. The effects may be observed at one or more loci, and include: 1) peak height imbalance of sister alleles in a heterozygous pair; 2) loss of data (referred to as 'allele drop out' when one or more alleles are missing at a locus and 'locus drop out' when all alleles are missing from a locus); 3) allele drop-in (allelic peak(s) in an electropherogram that are not reproducible); and 4) elevated stutter peaks
Changes in a DNA profile that generally occur when suboptimal or limiting quantities of DNA are tested.
NOTE This may be due to sampling variation (e.g., pipetting) of the target DNA that goes into the polymerase chain reaction (PCR) and/or random events between primers and target DNA during PCR amplification. The effects may be observed at one or more loci, and include: 1) peak height imbalance of sister alleles in a heterozygous pair; 2) loss of data (referred to as “allele drop out” when one or more alleles are missing at a locus and “locus drop out” when all alleles are missing from a locus); 3) allele drop-in [allelic peak(s) in an electropherogram that are not reproducible]; and 4) elevated stutter peaks (a non-allelic peak in the stutter position exceeding the stutter expectation of the laboratory).
The peak height value in a DNA electrophoretic profile above which it is reasonable to assume that, at a given locus, allelic drop out of a sister allele in a heterozygous pair has not occurred in a single source DNA sample; due to the possibility of shared alleles in mixed samples, the presence of allele peaks above the stochastic threshold is no guarantee that allele drop out did not occur in mixed DNA sample profiles.
in computer forensics, retrievable retention of data; electronic, electrostatic, or electrical hardware or other media into which data may be entered, and from which data may be retrieved.
any object on which data is preserved.
Short sequences of DNA that are repeated numerous times in direct succession. The numberof repeated units may vary widely between individuals and this high level of variationmakes STRs particularly useful for discriminating between people. The person to whom the data in the record applies. The subject of the record need notbe the subject of the transaction.
(1) a single fiber, filament, or monofilament; (2) an ordered assemblage of textile fibers having a high ratio of length to diameter and normally used as a unit; includes slivers, roving, single yarns, plied yarns, cords, braids, ropes, etc.
Discussion—A strand is often multiple plies joined together. The terms “ply” and “strand” are not synonymous; cordage can have a single-plied strand, but not a stranded ply.
A harsh vibrating sound heard during respiration in cases of obstruction of the air passages.
A harsh vibrating sound heard during respiration in cases of obstruction of the air passages.
The anatomical correctness of the feet and legs of an animal.
Surface topography measurement method whereby a light image with a known structure or patternis projected on a surface and the pattern of reflected light together with knowledge of the incidentstructured light allows one to determine the surface topography.
sample device with an adhesive surface used to collect materials for SEM/EDS analysis.
a group of fibers within a generic class that share the same base-polymer composition; sub-generic names include, for example, nylon 6 and nylon 6,6.
The placement of human remains under ground or surface area, i.e., buried or underwater
in computer forensics, a directory object contained within another directory object in a filesystem.
in facial identification, the facial image capture criteria described in ANSI/NIST-ITL 1-2011.
The person to whom the transaction applies. The subject of a record need not be thesubject of the transaction.
The placement of a document(s) into a liquid to facilitate cleaning, unfolding, or separation of the document(s).
The placement of a document(s) into a liquid to facilitate cleaning, unfolding, or separation of the document(s).
Willingness of the canine to yield to or cede control to a handler, another person or animal.
An order of the court for a witness to appear at a particular time and place to testify and/or produce documents in the control of the witness.
Recognition and response to trained target odor.
Surface upon which a friction ridge impression is deposited.