A.F.I.S. ( Automated Fingerprint Identification System)
A computer database of scanned and encoded fingerprints. A.F.I.S. can quickly search known files for comparison and matching to unknown fingerprints. A.F.I.S. is maintained by the F.B.I.
Algor Mortis
Measures how fast the body cools after death, which is an indicator in determining the time of death. The internal body temperature will begin to cool immediately after death. Depending on the environment it is in, the body will decrease in temperature 1
Arches
A pattern used in the identification of fingerprints. This is the simplest type of fingerprint but is also the least common. Arches do not have a core or a delta. Their curving ridgelines begin and end on opposite sides of the fingerprint.
Arson
Deliberately starting a fire to buildings or other property. Fire investigators examine all aspects of the remains left from the fire to determine how the fire was started.
Asphyxia
Depriving the body of oxygen causing either unconsciousness or death. Also called suffocation, asphyxia can be caused by a variety of things including breathing in smoke, carbon monoxide as well as other chemicals or limiting air intake.
Autopsy
An examination of a dead body in order to establish the cause and time of death. If the identity of the body is in question, the autopsy may also provide clues to aid in the identification process. An autopsy includes a thorough examination of the body's
Ballistics
The study of the effects of projectiles being fired. This most often involves bullets, shell casings, and firearms. Ballistic analysis looks at the motion, behavior, and effects of a projectile after it has been fired as well as gunshot residue that is pr
Blind Forgery
A phony signature where the suspect uses their normal handwriting to sign the other person's name. This type of forgery happens most often in cases of anonymous harassment or identity theft crimes. When the suspect is caught, this type of forgery is gener
Blood Spatter
The shape of bloodstains found at crime scenes. Analyzing blood spatter patterns can help an investigator determine whether or not a suspectis telling the truth and provide many clues that can help reconstruct a crime scene.
Blood Typing
A test performed to identify what type of blood is present in a sample. During the test, a drop of serum with known antibodies is added to a drop of the blood sample that has unknown antigens. There are four blood types: A, B, AB, and O. In forensic scien
Blowback
In broken glass, this is the scattering of the glass pieces backwards, toward whatever broke the glass. Glass has elasticity which can cause this type of movement. Blowback can cause small pieces of glass to fall onto a suspect's clothes and hair and can
Chain of Custody
The written record of who has handled the evidence. As evidence is moved around between police, investigators, examiners, prosecutors, and courts, a written record must be kept of who has had it, where it has been held, when it was received, and what, if
Chromatography
A scientific test that separates the parts of a mixture. The mixture is passed through a medium that causes the component parts to flow at different rates. A chromatogram is the equipment used to record the separations. Forensic examiners use this type of
Circumstantial Evidence
Evidence that implies something happened but doesn't actually prove it. This evidence can be based on suggestions, probability, and statistics instead of actual knowledge. When there are several pieces of circumstantial evidence pointing in the same direc
Civil Law
Private, non-criminal deals made between individuals or groups in order to formalize the boundaries of their relationships. Contracts, wills, prenuptials, marriages, divorces, property transfers, and negligence are all types of civil law cases. These case
Class Evidence
A type of evidence that identifies a group of similar individuals or objects and not a specific individual or object. For example, tennis shoes are a class and can be narrowed down by brand and size but that still leaves many possibilities of shoes. Howev
C.O.D.I.S. (Combined D.N.A. Index System)
The F.B.I. database of D.N.A. fingerprints collected from felons and evidence obtained at crime scenes. This nationwide database can be accessed by investigators to assist in identifying suspects and connecting several crimes together.
Confirmatory Test
A test that is looking for the presence of one specific substance. The procedures for these tests are more advanced than what is used in presumptive testing. Confirmatory tests are used to provide specific physical and testimonial evidence in court.
Control Sample
A sample from a known source that is used as a comparison to other unknown samples. In forensic science, control samples are taken from the victim and possible suspect(s). These control samples are then compared with the data/samples obtained from the evi
Core
The part of a fingerprint that is located close to the middle of the loop and whorl patterns. Both a core and delta are needed to make a positive identification of the owner of the fingerprint.
Coroner
The title for the head of a forensic investigative team who is elected or appointed and does not necessarily require a medical license. Coroners are not required to have any knowledge of or experience in medicine, therefore, this is becoming an outdated p
Crime Scene
A place where evidence is found. There are two types of crime scenes: primary crime scene and secondary crime scene. A primary crime scene is the place where the crime occurred. A secondary crime scene is a place that is related to the crime scene such as
Criminal Law
Involves offenses that are committed against individual and societal rights. In these cases, the state is the plaintiff rather than a particular individual. In criminal cases, guilt must be proven "beyond a reasonable doubt" to achieve a conviction. These
Criminalist
The general term for someone who collects data and analyzes the physical evidence. A criminalist does not handle a dead body. They can have a variety of backgrounds and specialties and generally are not police officers. A criminalist does not interrogate
Dactylscopy
The study of fingerprints. Throughout history, potters used their fingerprint to sign their pottery. In the 1800's. fingerprints were used to identify prisoners and to sign contracts. Through the years this study has evolved into an exact science that is
Daubert Ruling
This Supreme Court ruling allows new scientific techniques or theories that follow scientific method to be admitted as evidence in a federal court. This ruling updated the Frye Standard and prevents unacceptable delays by allowing testimony that is based
Delta
A part of a fingerprint that is triangular. Deltas are found in all loop and whorl fingerprint patterns. Both the delta and core locations are needed to make a positive identifications of the owner of the fingerprint.
Diacritics
In the study of handwriting, the manner of how the letter "t" is crossed and the letters "i" and "j" are dotted. Handwriting analysts look at the length of the line crossing the "t" and where it is located, as well as whether the "i" and "j" are dotted di
Electrophoresis
A test that uses charged particles to separate DNA fragments according to their size. In forensic science, this is one part of the tests that are used in DNA fingerprinting for comparing and identifying various evidence samples.
Erythrocytes
Red blood cells (RBCs). These cells contain antigens that are used in determining blood types. Red blood cells do not have nuclei so they do not have nuclear DNA.
Evidence
Any relevant information that will prove or disprove a fact or belief. The two general types of evidence are testimonial evidence and physical evidence. Testimonial evidence is a statement that is made in court under oath and is also called direct evidenc
Expert Witness
A person with a technical specialty who is allowed to present their opinion at trial without having witnessed the crime. They could be providing testimonial evidence on various aspects of the crime, evidence, victim or suspect related to their technical s
Felony
A serious crime usually involving violence. Auto theft, armed robbery, murder, rape, forgery, illegal drug dealing and fraud are examples of felonies. These are generally punished by long-term imprisonment of more than one year.
Fingerprints
Patterns of ridgelines in the skin on finger tips. These are unique and can positively identify individuals. The FBI is the law enforcement agency that maintains the national digital database of fingerprints called AFIS.
Modus Operandi (MO)
The characteristics or specific method of operation that a criminal uses to commit a crime. Suspects can be connected to several different crimes by comparing the modus operandi of the crimes.
Nuclear DNA
DNA (deoxyribonucleic acid) that comes from the nuclei of the cell and is inherited from both parents. Nuclear DNA is located in white blood cells. This type of DNA that is used in most DNA testing.
Traced Forgery
A fake signature made by tracing over the original signature. This can be done by using carbon paper, a light box or tracing an indentation made on another paper. Traced forgery is able to be discovered using sophisticated microscopes.
Visible Fingerprints
A type of fingerprint left form a finger that has touched some type of colored materials such as blood, ink, or grease. It is a fingerprint that investigators can see with the naked eye.
Leucocytes
White blood cells (WBCs). These contain antibodies and are the main cells of the body's immune system. White blood cells have nuclei which contain nuclear DNA. Nuclear DNA is the most common type of DNA used for analysis.
Livor Mortis
An indicator in determining the time of death that analyzes the skin color to find where the blood has collected after the heart stopped. Gravity causes the blood to pool causing a red-purplish discoloration on the body. This begins within 30 minutes afte
Probative Value
The ability of evidence to prove that something is related to a crime. The higher the probative value that a piece of evidence has, the more helpful and important that evidence becomes. To improve the probative value of class evidence, investigators need
Rigor Mortis
An indicator in determining the time of death that measures the inflexibility of the skeletal muscles which is caused by the loss of adenosine triphosphate (ATP). Rigor mortis begins with the small muscles of the face, neck, and jaw within 2 to 3 hours af
Individual Evidence
Evidence that is linked to a single source such as DNA patterns of fingerprints. Identifying individual evidence always requires some type of comparison with a control or other similar evidence. This type of evidence will point directly to a specific sour
Latent Fingerprints
A type of fingerprint left by perspiration and body oils. Latent fingerprints are invisible and are found by using certain chemicals or some other physical means like powder. An example of a latent fingerprint would be someone's perspiration left on a sin
Locard Exchange Principle
Edmond Locard's theory that "every contact leaves a trace". Edmond Locard was a forensic investigator in the early 1900's. According to Locard's principle your hair will be left on clothing or blankets and fingerprints or shoeprints will be left on things
Loops
A pattern used in the classification of fingerprints. This is the most common type of fingerprint. All loops have a single core and a single delta. they are made of ridgelines that begin and end on the same side of the print and have a large curve in the
Simulated Forgery
A phony signature made by someone who is looking at an actual signature and trying to copy it so that the forgery looks like the original. When analyzing a simulated forgery, investigators may find many short strokes from the suspect hesitating as they ar
Spectroscopy
A test that measures the color on an infrared (IR) spectrum that is created when matter interacts with electromagnetic radiation. In forensic science, this test is used to identify an unknown substance or compound by comparing the IR spectrum to a known s
Hair Cuticle
The outside layer of hair covering the hair shaft. The cuticle has scales that form into patterns. In forensic science, these scale patterns are used to tell if the hair is human hair and to match different hair samples. Human hair has finer scale pattern
Hair Medulla
A row of cells going down the center core of the hair shaft. The cells vary depending on whether they are empty or filled with air, pigment or color. These cells can be a continuous strand or fragmented. the medulla allows forensic examiners to identify w
Glass Fracture Patterns
The shape of the cracks or fractures in broken glass. In forensic science, studying the patterns of the cracks, their shape, stress marks and on which side the break occurred in the glass, helps examiners to reconstruct the crime scene.
Hair Cortex
This is the largest portion of a shaft of human hair. It contains the color pigment. In forensic science, the cortex is studied to match hair samples, identify their sources and determine race.
Watermark
A light design made in paper which identifies the manufacturer of the paper. This is done by reducing the amount of fibers in certain areas. In forensic science, investigators analyze the watermark to identify specific types of papers and when it was made
Whorls
A pattern used in classification of fingerprints. All whorls include a core and at least two deltas. In a whorl, the ridgelines spiral around the core.
Precipitin Test
This is the standard method of testing blood to determine if it is from a human or an animal. This test uses antigens and antibodies and is similar to tests for blood typing. It is a very sensitive test so it can even be used on bloodstains.
Presumptive test
A screening test that is administered because there is the assumption that a particular substance is present. Examples of a presumptive test are field sobriety test and breathalyzer test given to someone who is suspected of driving under the influence (DU
Forensic Anthropology
A specific form of anthropology that specializes in studying the human skeletal system to identify unknown remains and the possible cause of death. The information is used to answer legal questions and provide testimony.
Frye Standard
Called the "general acceptance" test, this Supreme Court ruling dictates that the science behind any evidence must be proven science. The science must be presented by an expert witness in the particular field of study. This eliminates "junk" science that
Misdemeanor
A minor crime. Theft or small dollar amounts, minor assaults and possession of small amounts of drugs are examples of misdemeanors. These are generally punished by fines, community service, probation, and no more than one year in jail.
Mitochondrial DNA (mDNA)
DNA (deoxyribonucleic acid) that comes from mitochondria which is found inside the cell and is inherited only from the mother. Mitochondrial DNA rarely mutates, is very durable and allows for reliable DNA testing of very old and small samples. Mitochondri
Humus
The organic material in soil. It comes from leaves and other plant materials that decompose into the soil. In forensic science, soil from crime scene is analyzed to find out if it naturally occurs in the area it was found or if it came from someplace else
Incendiary
A fire that was intentionally set by arsonist. By investigating the scene of the fire, fire marshals are often able to determine the cause of the fire.
Oblique Lighting
Sweeping a flashlight beam back and forth over a hard surface in a semi-dark indoor area. This light can show items that are not visible in normal light.
Obliteration
The changing of documents by erasing words, phrases, or sentences. This can be done with an eraser, scraping off words or using chemicals. Obliteration removes the finishes on the paper. This is able to be detected in microscopic analysis.
Odontology
The study of teeth including bite marks and tooth structure. Forensic pathologists commonly use dental records and x-rays to positively identify a corpse.
Osteology
The study of bones. Forensic science uses the bones to determine if the remains are human or animal; the original size of the body; its gender; race; age; and the possible cause of death.
Medical Examiner
The title for a licensed physician, who is the head of a forensic investigative team. Many medical examiners are also trained pathologists that specialize in forensics.
Minutiae
The various ridge characteristics used to individualize a fingerprint pattern. There are many different minutiae within any one fingerprint pattern. Several common minutiae are: island, bridge, spur, delta, dot, forks, ridge ending and eye. In order to ma
Pathology
The scientific study that deals with the causes and effects of disease. In forensic science, it involves laboratory tissue sampling to determine the causes of sudden or violent death. In a crime lab, the forensic pathologist is in charge of all the eviden
Physical Evidence
A tangible object that is relevant to a crime. It can include clothing, DNA, blood, fingerprints, broken glass or most anything else that can be used to show that a crime was committed, the identity of a suspect, reconstruction of a crime, or back up othe
Plastic Fingerprints
A type of fingerprint left as an impression in some moldable or soft material lie a bar of soap, fresh paint, or chocolate. This is a three-dimensional print which forms a negative impression. Also called indented or molded fingerprints.
Polymerase Chain Reaction (PCR)
A laboratory procedure that can make multiple copies of very small DNA samples for additional testing. This simple procedure quickly replicates the DNA and makes it possible to analyze very small amounts of DNA found in samples collected by investigators.
Statutory Law
The rules of law that have been established by the federal, state, or local governments, Statutory law is based on the standards in the U.S. Constitution.
Testimonial Evidence
Evidence that is given as a statement under oath. This includes statements made by competent eye witnesses as well as other experts who can testify to various aspects of the crime, evidence, victim or suspect. Testimonial evidence is also called direct ev
Toxicology
The study of poisons or chemicals and their effect on living organisms. In forensic science, scientists try to identify the poison and also look for how it was administered to the victim, the quantity of poison given, and the time period over which the po
Toxin
A naturally occurring poison that causes harm or injury when it comes into contact with a living thing. These generally include venoms from plants and animals or microorganisms that can be absorbed, digested or injected into the body and kill rapidly in s