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 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 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 lower 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.
The minimum peak height (Relative Fluorescence Units, in RFUs) requirement at and above which detected peaks on a DNA electropherogram can be reliably distinguished from instrument background noise.
A method of estimating stature that involves measuring all bones constituting the components of stature, summing those measurements, and correcting for the missing soft tissue.
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.
A creature or living being, other than human. The legal definition of animal may be further defined by local law.
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.
A deviation from typical skeletal anatomy; often 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 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.
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.
A skeletal condition, defect, or anomaly that occurred before an individual’s death, with evidence of a biological reaction.
A skeletal defect that occurred before an individual’s death and shows evidence of osteological 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.
request by the provider of the item of inspection to the inspection body for reconsideration by that body of adecision it has made relating to that itemNOTE Adapted from ISO/IEC 17000:2004, definition 6.4.
Request by the provider of the item of inspection to the inspection body for reconsideration by that body of a decision it has made relating to that item
A request by a forensic science service provider to the inspection body for reconsideration by that body of a decision, finding, or other action.
This refers to devices that have successfully completed a test of fingerprint capture devices that is performed in accordance with procedures established by the FBI in EBTS Appendix F. [2013a]
a relationship where an individual works for an entity while learning skills.
Permission for a product or process to be marketed or used for stated purposes or under stated conditions. Approval can be based on fulfillment of specified requirements or completion of specified procedures.
Acceptable to the authority having jurisdiction
Acceptable to the authority having jurisdiction
See shaping.
A high-temperature luminous electric discharge across a gap or through a medium such as charred insulation.
Identifying and documenting a fire pattern derived from the identification of arc sites used to aid in determining the area of fire origin or spread.
Melting of conductors and conducting surfaces as a result of electrical arcing. The characteristics of arc melting are described in 9.11.1.1.
The location on a conductor with localized damage that resulted from an electrical arc.
in computer forensics, a bit stream duplicate of data placed on media that is suitable for long-term storage.
Arcing associated with a matrix of charred material (e.g., charred conductor insulation) that acts as a semiconductive medium.
A structure, part of a structure, or general geographic location within a fire scene, in which the 'point of origin' of a fire or explosion is reasonably believed to be located. (See also 3.3.149, Point of Origin.)
The act of using a canine to search a designated area for a target odor/scent.
Surface measurement method that produces a topographical image of a surface, which may berepresented mathematically as a height function z (x, y) of two independent variables (x, y).
a major group of unsaturated cyclic hydrocarbons containing one or more rings, typified by benzene, which has a 6-carbon ring containing nominally three double bonds.
Discussion—In fire debris, this term is typically used to refer to alkylbenzenes, which are benzene rings with aliphatic substitutions.
a sharp line on the fracture surface defining the crack front shape of an arrested or momentarily-hesitated crack.
A condition in which the heart beats with an irregular or abnormal rhythm
A condition in which the heart beats with an irregular or abnormal rhythm.
A fire pattern displayed on the cross-section of a burned wooden structural member.