Term

Definition

Source

A.F.I.S.

Automated Fingerprint Identification System

NIJ

alternative light systems (ALSs)   

Portable lasers and handheld ultraviolet lighting used to locate physical evidence at the crime scene; particularly helpful in locating trace evidence.

COPS

ASCLD/LAB

American Society of Crime Laboratory Directors/Laboratory Accreditation Board. This is an organization whose assessors inspect forensic labs for accreditation.

DDC

associative evidence   

Bidirectional evidence that connects the perpetrator to the scene or victim or connects the scene or victim to the perpetrator.

COPS

Bindle paper

Clean paper folded for the containment of trace evidence, sometimes included as part of the packaging for collecting trace evidence

NIJ

Biohazard bag

A container for materials that have been exposed to blood or other biological fluids and have the potential to be contaminated with hepatitis, AIDS, or other contagions.

NIJ

Biological Evidence

Evidence commonly recovered from crime scenes in the form of hair, tissue, bones, teeth, blood or other bodily fluids.

NIJ

Biological fluids

Fluids that have human or animal origin, most commonly encountered at crime scenes (e.g., blood, mucous, perspiration, saliva, semen, vaginal fluid and urine).

NIJ

Boundaries

The perimeter or border surrounding potential physical evidence related to the crime.

NIJ

Case file

The collection of documents comprising information concerning a particular investigation. (This collection may be kept in case jackets, file folders, ring binders, boxes, file drawers, file cabinets or rooms. Sub-files are often used within case files to segregate and group interviews, media coverage, laboratory requests and reports, evidence documentation, photographs, videotapes, audiotapes, and other documents.)

NIJ

Case Identifiers

The alphabetic and/or numeric characters assigned to identify a particular case.

NIJ

Cell

The smallest component of life capable of independent reproduction and from which DNA is isolated for forensic analysis.

NIJ

chain of custody   

The witnessed, unbroken, written chronological record of everyone who had an item of evidence and when each person had it; also accounts for any changes in the evidence.

COPS

Chain of Custody

A record of individuals who have had physical possession of the evidence and the process used to maintain and document the chronological history of the evidence. (Documents can include, but are not limited to- name or initials of the individual collecting the evidence, each person or entity subsequently having physical possession of it, dates the items were collected or transferred, where the item(s) were collected from, agency and case number, victim's or suspect's name (if known), and a brief description of the item.)

NIJ

Chromosome

The biological structure by which hereditary information is physically transmitted from one generation to the next.

NIJ

Clean/sanitize

The process of removing biological and/or chemical contaminants from tools and/or equipment.

NIJ

CODIS

COmbined DNA Index System is an electronic database of DNA profiles. These profiles are generated from convicted offenders and/or from crime scene evidence. State statutes determine which offenses are required to be included in the database. The database also includes a missing persons index.

NIJ

cold case

Refers to a criminal investigation (or "case") that remains unsolved and "on the books." Typically, cold cases are violent or other major felony crimes, such as murder or rape; unsolved minor crimes are generally subject to a statute of limitations. A case is considered unsolved until a suspect has been identified, charged, and tried for the crime. A case that goes to trial and does not result in a conviction can also be kept on the books pending new evidence. Many times, those investigating the case have a suspect in mind but have not been able to find evidence sufficient to charge the suspect with the crime. With the advent of improving DNA testing and other forensics technology, many cold cases are being re-opened and prosecuted. Police departments are opening cold case units whose job is to re-examine cold case files.

COPS

Collect/collection

The process of identifying, documenting, gathering and packaging or retaining physical evidence.

NIJ

Combined DNA Index System (CODIS)   

Developed by the FBI, a database of convicted-offender and known- and unknown-subject DNA profiles that is used to find matches and to link unsolved crimes in multiple jurisdictions.

COPS

Contamination

The undesirable transfer of material to physical evidence (DNA) from another source.

NIJ

Control Samples

Cuttings, swabbings, etc. from unstained adjacent material. A control sample is material of a known source that presumably was uncontaminated during the commission of the crime (e.g., a sample to be used in laboratory testing to ensure that the surface on which the sample is deposited does not interfere with testing. For example, when a bloodstain is collected from a carpet, a segment of unstained carpet must be collected). The control sample should be taken adjacent to the biological stain being collected.

NIJ

Controls

Tests designed to demonstrate that a procedure worked correctly and performed in parallel with experimental samples.

NIJ

crime scene   

The location at which a crime was committed.

COPS

crime scene entry log   

A written chronological record of all persons who enter and leave the crime scene and the times they do so.

COPS

Cross Contamination

The undesirable transfer of material between two or more sources of physical evidence.

NIJ

cross-examination   

In a trial, the questioning of a witness who was initially called by the opposing party.

COPS

deoxyribonucleic acid (DNA)   

A nucleic acid consisting of the molecules that carry the body's genetic material and establish each person as separate and distinct.

COPS

Disposable instruments

Items that will be used only once to collect evidence, such as biological samples, then discarded to minimize contamination (e.g., tweezers, scalpel blades, droppers).

NIJ

DNA (Deoxyribonucleic acid)

The molecule that encodes genetic information. DNA is a chemical substance contained in cells which determines each person's individual characteristics. An individual's DNA is unique except in cases of identical twins.

NIJ

DNA Analysis

The process of testing to identify DNA patterns or types. In the forensic setting, this testing is used to exclude or include individual's as possible sources of body fluid stains (blood, saliva, semen) and other biological evidence (bones, teeth, hair). This testing can also be used to indicate parentage.

NIJ

DNA Profile

The result of the determining the relative positions of DNA sequences at several locations on the molecule. Each person (except identical twins) has a unique DNA profile when used in the context of the CODIS database, which evaluates 13 specific DNA locations.

NIJ

Documentation

Written notes, audio/videotapes, printed forms, sketches and/or photographs that form a detailed record of the scene, evidence recovered, and actions taken during the search of the crime scene, including chain of custody information.

NIJ

Double Helix

The shape the DNA assumes after it replicates during cell life.

NIJ

Electropherogram

The graphic representation of the separation of molecules by electrophoresis or other means of separation.

NIJ

Electrophoresis

A method of separating large molecules (such as DNA fragments) from a mixture of similar molecules. An electric current is passed through a medium at a different rate, depending on its electrical charge and size. Separation of DNA markers is based on these differences.

NIJ

Elimination/ Reference samples

A term used to describe a sample of known source taken for comparison purposes.

Example:

An elimination sample is one of known source taken from a person who had lawful access to the crime scene (e.g. blood or cheek [buccal] swabs for DNA analysis, fingerprints from occupants, tire tread impressions from police vehicles, footwear impressions from emergency medical personnel) to be used for comparison with evidence of the same type.

A reference sample is material of a verifiable/documented source which, when compared with evidence of an unknown source, shows an association or linkage between an offender, crime scene and/or victim (e.g., a carpet cutting taken from a location suspected as the point of transfer for comparison with the fibers recovered from the suspect's shoes, a sample of paint removed from a suspect's vehicle to be compared with paint found on a victim's vehicle following an accident, or a sample of the suspect's and/or victim's blood submitted for comparison with a bloodstained shirt recovered as evidence).

NIJ

evidence   

Anything that tends logically to prove or disprove a fact at issue in a judicial case or controversy.

COPS

Evidence

Something that can help identify the responsible persons, establish an element of crime, reconstruct crime events or link crimes.

NIJ

evidence recovery log   

A chronological record of each item of evidence, listing who collected it, where and when it was collected, who witnessed the collection, and whether it was documented by photos or diagrams.

COPS

Exclusion

A DNA test result indicating that an individual is excluded as the source of the DNA evidence. In a criminal case, "exclusion" does not necessarily equate to "innocence."

NIJ

Exclusion

An exclusion result means that the DNA test has revealed a non-match in the DNA profiles of the tested unknown evidentiary sample compared to the known sample from an individual.

DDC

First responder(s)

The initial responding law enforcement officer and/or other public safety official or service provider arriving at the scene prior to the arrival of the investigator in charge.

NIJ

Forensic Hit

A CODIS match between two or more crime scene profiles.

NIJ

Forensic Science

The application of science to analyze evidence involved in criminal and civil litigation.

NIJ

Fragile evidence

Evidence that will lose its evidentiary value if not preserved and protected, either because of its nature or the conditions at the scene (e.g., blood in the rain).

NIJ

Gene

The basic unit of heredity.

NIJ

Genetics

The study of the patterns of inheritance of specific traits.

NIJ

Genotype

The genetic makeup of an organism.

NIJ

hepatitis B (HBV) and

hepatitis C (HCV)   

Viruses present in blood (and, for HBV, other bodily fluids) that attack the liver and can lead to death; a health hazard at scenes where bodily fluids are exposed.

COPS

Heredity

The transmission of characteristics from one generation to the next.

NIJ

Inclusion

An inclusion result means that the DNA test has revealed a match in the DNA profiles of the tested unknown evidentiary sample compared to the known sample from an individual.

DDC

known samples   

(1) Standard or reference samples from known or verifiable sources; (2) control or blank samples from known sources believed to be uncontaminated by the crime; (3) elimination samples from sources who had lawful access to the crime scene.

COPS

Latent print

A print impression that is not readily visible, made by contact with a surface.

NIJ

Locus (pl. loci)-

The specific physical location of a gene on a chromosome.

NIJ

Marker

Pieces of DNA sequence of known locations on chromosomes that are used to identify the specific genetic variations an individual possesses.

NIJ

Measurement scale

An object showing standard units of length (e.g., ruler) used in photographic documentation of an item of evidence.

NIJ

mitochondrial DNA (mtDNA)   

DNA found in the mitochondria of a cell; inherited only from the mother and thus serves as an identity marker for maternal relatives.

COPS

Mixture profile

A mixture profile means that there are more than two alleles present at a given locus, indicating there is more than one contributor to the sample. Mixture profiles are common in forensic cases and must be interpreted carefully.

DDC

negative match   

In DNA analysis, a lack of a match between a suspect's DNA and that found on evidence at the crime scene.

COPS

Nonporous Container

Packaging through which liquids or vapors cannot pass (e.g., glass jars or metal cans).

NIJ

nuclear DNA   

DNA found in the nucleus of a cell; inherited from both the mother and the father.

COPS

Offender Hit

A CODIS match between a crime scene profile and an offender profile.

NIJ

personal protection equipment (PPE)   

Equipment and clothing designed to protect individuals at high-risk crime scenes from injury and infection.

COPS

Personal Protective Equipment (PPE)

Articles such as disposable (latex) gloves, masks, shoe covers and eye protection that are utilized to provide a barrier to keep biological or chemical hazards from contacting the skin, eyes, and mucous membranes and to avoid contamination of the crime scene.

NIJ

Polymerase Chain Reaction (PCR)

A duplicating process that yields millions of copies of a desired portion of DNA through repeated cycling of a reaction, using heating/cooling and chemicals. This process enables scientists to obtain genetic information from small or degraded specimens.

NIJ

positive match   

In DNA analysis, an identical match of a suspect's DNA with that found on evidence at the crime scene.

COPS

Restriction enzyme

A protein harnessed from bacteria that recognizes specific, short nucleotide sequences and cuts DNA at those sites.

NIJ

Restriction fragment length

polymorphism (RFLP)-

The variation between individuals in DNA fragment sizes cut by specific restriction enzymes.

NIJ

Sequencing

Determination of the order of base sequences in a DNA molecule.

NIJ

Serology

Serology is the study and analysis of body fluids. In forensic cases, serology is one of the first steps in determining the origin of a stain, such as blood, semen or saliva.

DDC

Short Tandem Repeats (STR)

Multiple copies of a short identical DNA sequence arranged in direct succession in particular regions of chromosomes.

NIJ

Single-use Equipment

Items that will be used only once to collect evidence, such as biological samples, then discarded to minimize contamination (e.g., tweezers, scalpel blades, droppers).

NIJ

sperm   

Tadpole like organisms that are contained in and travel through semen to fertilize the female egg.

COPS

Trace evidence

Physical evidence that results from the transfer of small quantities of materials (e.g., hair, textile fibers, paint chips, glass fragments, gunshot residue particles).

NIJ

unknown or questioned samples   

(1) Recovered crime scene samples whose sources are in question; (2) questioned evidence that may have been transferred to an offender during the commission of a crime and been taken away by him or her; (3) questioned evidence recovered at multiple crime scenes that associates a particular tool, weapon, or person with each scene.

COPS

Walk-through

An initial assessment conducted by carefully walking through the scene to evaluate the situation, identify potential evidence, and determine resources required. It can also be a final survey conducted to ensure the scene has been effectively and completely processed.

NIJ

walk-through (of crime scene)   

The investigator's initial overview of the crime scene, performed by walking through the area, to locate and view the body, identify evidence, and determine procedures for examination and documentation of the scene and body.

COPS

Y-STR

Y-STR is DNA found on the Y-chromosome that is paternally inherited and therefore not unique to an individual. Y-STR testing is often used to help decipher a male DNA profile in a mixture of male and female in a DNA sample.

DDC