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 widely used cryptographic hash function producing a 16-byte hash value, typically expressed in text format as a32-digit hexadecimal number. MD5 is commonly used to verify data integrity.
a feature or property of a sample that does not fall within the variation exhibited by the comparison sample, considering the limitations of the sample or technique, and therefore indicates the two samples do not share a common origin.
Discussion—The use of this term does not imply the formal application of statistics.
a feature or property of a sample that does not fall within the variation exhibited by the comparison sample, considering the limitations of the sample or technique, and therefore indicates the two samples do not share a common origin. The use of this term does not imply the formal application of statistics.
Quantity intended to be measured. VIMa
quantity intended to be measured
A physical quantity or property which is measured.
Quantity intended to be measured
Make a measurement.
quantity value representing a measurement resulth
h: Joint Committee for Guides in Metrology (JCGM), International vocabulary of metrology - Basic and general concepts and associated terms (VIM) (Sèvres, France: International Bureau of Weights and Measures [BIPM]- JCGM 200) available at https://www.bipm.org/en/publications/guides.
Process of experimentally obtaining one or more quantity values that can reasonably be attributed to a quantity.
process of monitoring the validity of the calibrations performed
System of coordinates that represent the geometry of the measured surface.NOTE If the nominal surface is a plane (or portion of a plane), it is common to use a rectangular coordinatesystem in which the axes form a right-handed Cartesian set, the X-axis being the direction of tracing co-linearwith the mean line, the Y-axis also lying on the nominal surface, and the Z-axis being in an outward direction(from the material to the surrounding medium).
Reference, with a stated value and associated measurement uncertainty, used to calibrate or verify measuring instruments or measuring systems
non-negative parameter characterizing the dispersion of the quantity values being attributed to a measurand, based on the information used (also uncertainty of measurement, uncertainty.)
Discussion—Measurement uncertainty includes components arising from systematic effects, such as components associated with corrections and the assigned quantity values of measurement standards, as well as the definitional uncertainty. Sometimes estimated systematic effects are not corrected for but, instead, associated measurement uncertainty components are incorporated. The parameter may be, for example, a standard deviation called standard measurement uncertainty (or a specified multiple of it), or the half-width of an interval, having a stated coverage probability. Measurement uncertainty comprises, in general, many components. Some of these may be evaluated by Type A evaluation of measurement uncertainty from the statistical distribution of the quantity values from series of measurements and can be characterized by standard deviations. The other components, which may be evaluated by Type B evaluation of measurement uncertainty, can also be characterized by standard deviations, evaluated from probability density functions based on experience or other information. In general, for a given set of information, it is understood that the measurement uncertainty is associated with a stated quantity value attributed to the measurand. A modification of this value results in a modification of the associated uncertainty.
element in the optical path of a MSP system that limits the area of illumination reaching the detector focal plane.
the process of inspecting, identifying, and noting the properties of media.
objects on which data can be stored.
The middle segment of the finger. The thumb does not have a medial segment.
Appointed forensic pathologist whose duty is to oversee medicolegal death investigations, perform postmortem examinations, and certify cause and manner of death. In some jurisdictions, individuals with other qualifications hold the title “Medical Examiner,” but for purposes of this document those individuals are considered medicolegal death investigators.
An appointed forensic pathologist whose duty is to oversee medicolegal death investigations, perform postmortem examinations, and certify cause and manner of death. In some jurisdictions, individuals with other qualifications hold the title 'Medical Examiner', but for purposes of this document those individuals are considered medicolegal death investigators.
A person or agency charged by law with conducting death investigations for the purpose of certifying deaths.
Formal inquiry into the circumstances surrounding the death of a human being; investigative information is considered with autopsy findings and adjunctive studies (if performed) to determine the cause and manner of death.
A formal inquiry into the circumstances surrounding the death of a human being; investigative information is considered with autopsy findings and adjunctive studies (if performed) to determine the cause and manner of death.
Person or persons whose duty it is to perform medicolegal death investigations for a designated jurisdiction and ensure certification of cause and manner of death; duties vary based on local enabling statutes.
Physical location of an agency (usually a medical examiner or coroner office) with the authority to perform medicolegal death investigations.
The statutorily established infrastructure (e.g., county coroner or state medical examiner) that exists to conduct medicolegal death investigations within a defined geographic area.
Medicolegal death investigation office (usually medical examiner or coroner office) within a state or district that is a jurisdictional unit and, which may have a single chief medicolegal officer.
Individual who performs medicolegal death investigations and includes those who have not completed the requirements for certification and is not certified.
An individual who performs medicolegal death investigations.
The medicolegal investigation includes the collection of data, photographs, evidence, witness interviews, external examination of the body at the scene, and other forensic information and analysis that will contribute to the identification of decedent, determination of cause and manner of death, reconstruction of the accident or crime scene, and support the provision of survivability factors.
Relevant to the medicolegal death investigation system; anthropologically, this term typically refers to human skeletal material of recent origin.
the core of the hair shaft that is composed of vacuoles and cells that can be air- or fluid-filled.
Discussion—The medulla (if present) occurs in a continuous, discontinuous, or fragmented pattern along the length of a hair and appears translucent or opaque.
the central portion of a hair composed of a series of discrete cells or an amorphous spongy mass.
Discussion—The medulla can be air-filled, and if so, appears opaque or black using transmitted light or white using reflected light. In animal hair, several types have been defined: uniserial or multiserial ladder, cellular or vacuolated, and lattice.
in computer forensics, (1) hardware used for the temporary storage of operating instructions and data while a digital device is running, and (2) see random access memory.
in computer forensics, the modification of data by a running system during the memory acquisition process.
A reference to the basic principles that govern the transmission of genetic traits from parents to offspring discovered by Gregor Mendel in the late 19th century.
The level of awareness and response to the environment.
The level of awareness and response to the environment.
Documentation relevant to the biometric data, but not the biometric data itself.Metadata may include both signal/sample-related and content-related information.Examples are the format of the data file, such as WAV and the scope of accreditation ofa DNA processing laboratory.
data, frequently embedded within a file, that describes a file or directory.
A self-inking stamp with a metal container instead of plastic.
two or more samples that appear to have the same color under one type of illumination but can appear dissimilar under different lighting conditions, or two or more samples that appear to be the same color under all lighting conditions, yet their reflectance/transmittance spectral curves are different.
when colors are perceived to be matching despite having different spectral profiles.
Discussion—These spectral differences often become apparent under different illumination conditions.
A combination of procedural steps used to perform a specific technical process. The method includes the validated steps, reagents, and critical instruments needed to perform the process or portion of a process. The same method may be conducted using different equipment (automated vs manual) when appropriately validated.1
A quantitative procedure by which a known concentration of the target analyte is added to multiple aliquots of the case sample(s)
Methodology refers to the categories of methods used to perform a stage of a DNA typing technology or technologies. For example, methodologies for STR technology can include extraction, quantification, amplification, and detection.
An estimate based on measurement of skeletal elements.
Property of a measurement result whereby the result can be related to a reference through a documented unbroken chain of calibrations, each contributing to the measurement uncertainty.