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.
a class of unsaturated aliphatic hydrocarbons hav- ing one or more double bond(s); also known as olefin.
DISCUSSION—In the plural form, also sometimes used in fire debris analysis to refer to the general class of aliphatic compounds with one or more double bonds.
One of two or more versions of a genetic sequence at a particular location in the genome.
One member of a series of possible alternative forms of a DNA sequence found at aparticular genetic location.
The value identified for the allele, either via expert system or by an analyst.
A composition of DNA fragments that represents common alleles at a locus
in computer forensics, the portions of storage that are assigned or reserved for active instructions or for data.
a solid or liquid mixture of two or more metals, or of one or more metals with certain non-metallic elements, as in carbon steels.
A modification made to a document by any combination of physical, chemical, or mechanical means including, but not limited to, obliterations, additions, overwritings, or erasures.
The result of changing something.
Equipment used to produce light (or to restrict light) at various wavelengths to enhance orvisualize potential items of evidence
Equipment used to produce light at various wavelengths to enhance or visualize potential items ofevidence.
Someone's or something's surroundings, especially as they pertain to the local environment; for example, ambient air and ambient temperature.
A report used to document any subsequent modifications, particularly those that affect or correct an original result or interpretation
A voluntary national, not-for-profit, independent professional certification board that has been established to promote the highest standards of practice for medicolegal death investigators (see www.abmdi.org).
The United States' largest dental association and the leading source of oral health-related information for dentists and their patients
The maximum current, in amperes, that a conductor can carry continuously under the conditions of use without exceeding its temperature rating.
The unit of electric current that is equivalent to a flow of one coulomb per second; one coulomb is defined as 6.24 _ 1018 electrons.
Any PCR amplification product.
An increase in the number of copies of a specific DNA fragment; can be in vivo or in vitro. In forensic DNA testing laboratories, this refers to the use of the PCR technique to produce many more copies of DNA at specific genetic loci.
An increase in the number of copies of a specific DNA fragment. In forensic DNA testing laboratories, this refers to the use of the PCR technique to produce many more copies of fragments at specific genetic loci from samples of known and unknown origin for the purpose of generating DNA profiles for comparison.
the active growth phase of a hair follicle in the hair growth cycle.
Discussion—The root from a pulled anagen hair is elongated and is usually fully pigmented.
A qualified individual who conducts and/or directs the analysis of forensic casework samples, interprets data, reaches conclusions, and/or issues reports concerning conclusions.
A qualified individual who conducts and/or directs the analysis of forensic casework samples, interprets data, reaches conclusions, and/or issues reports concerning conclusions.
A chemical substance to be identified and/or measured.
Includes all targeted compounds in a screening assay, as well as compounds being quantitated and/or confirmed
A set of standards, controls, and/or case samples that are contemporaneously prepared and/or analyzed a particular sequence..
A selection of drugs, drug metabolites, and other chemicals covered in an analytical testing scheme.
A selection of drugs, drug metabolites, and other chemicals covered in an analytical testing scheme.
A selection of drugs, drug metabolites and other chemicals covered in an analytical testing scheme.
The lowest amount of an analyte that can be reliably measured in a specimen by a laboratory test;may be a decision point, a limit of detection, or a lower limit of quantitation.
The lowest amount of an analyte that can be reliably measured in a specimen by a laboratory test; may be a decision point, a limit of detection or a limit of quantitation
1) The minimum height requirement at and above which detected peaks on a STR DNA profile electropherogram can be reliably distinguished from background noise; peaks above this threshold are generally not considered noise and are either artifacts or true alleles. 2) A 'Relative Fluorescence Units' (RFU) level determined to be appropriate for use in the PCR/STR DNA typing process; a minimum threshold for data comparison is identified by the specific forensic laboratory through independent validation studies.
a biogeographic designation of human populations (for example, Asian, African, European) whose hair can share similar morphological and microscopic traits.
Discussion—The racial terms Caucasoid, Mongoloid, and Negroid should not be used as these terms are no longer acceptable in the field of anthropology (the field from which these designations originated).
A mixture that consists of ammonium nitrate and fuel oil.
an ion having a negative charge.
Discussion—Examples of anions are NO3- in KNO3 or ClO4- in NH4ClO4.
a characteristic of an object in which the refractive index differs depending on the direction of propagation or vibration of light through the object.
A skeletal deviation from normal. It is typically nonlethal or nondisruptive to function; it may or may not have clinical or forensic significance.
The American National Standards Institute, Inc.
Prior to death.
Antemortem (AM) records are impressions of friction ridge details collected from live subjects, and can come from any part of friction ridge skin. Friction ridge skin is present on the palmar and plantar surfaces of the hands and feet. As such, impressions from the fingers and palms of the hands as well as the toes and soles of the feet can all be used for personal identification purposes. During antemortem fingerprint recovery, the living subject is usually manipulated against the recording medium. Postmortem (PM) records are records collected from deceased subjects. During PM fingerprint recovery, the recording medium is usually manipulated against the deceased subject in the same manner as the antemortem records. Unless a manual comparison is available, an AFIS search of an unidentified postmortem fingerprint record is used as a tool to find antemortem fingerprint records in order to establish or verify the deceased subject's identity.
Antemortem (AM) records are records collected from live subjects, and can come from any part of friction ridge skin. Friction ridge skin is present on the palmar and plantar surfaces of the hands and feet. As such, impressions from the fingers and palms of the hands as well as the toes and soles of the feet can all be used for personal identification purposes. During antemortem friction ridge print recovery, the living subject is usually manipulated against the recording medium. Postmortem (PM) records are records collected from deceased subjects or remains. During postmortem friction ridge recovery, the recording medium is usually manipulated against the deceased subject in the same manner as the antemortem records. Unless a manual comparison is available, an AFIS search of an unidentified postmortem impression is used as a tool to find antemortem records in order to establish or verify the deceased subject's identity.
A skeletal condition, defect, or anomaly that occurred before an individual’s death, with evidence of a biological reaction.
Relating to having origins in human activity.
in facial identification, an explicit measurement of landmarks on a face and a comparison of these measurements between two samples.
the application of a process to modify, conceal or destroy information to inhibit or prevent the effectiveness of forensic science examinations.
an opening in an optical system that controls the amount of light passing through a system.
a beam-restricting orifice in an electron optical column; the orifice diameter influences the beam current and depth of focus.