|
Glossary
ALCOHOL /
DUI
Measuring the quantity of alcohol in the blood is one of the three methods
available to assess alcohol impairment. This is usually accomplished by an
instrumental chemical analysis of the blood to measure the blood alcohol concentration. A practical method for
monitoring alcohol impairment in driving is breath analysis via breath testing
devices. These breath analyzers measure the amount of alcohol in breath and
translate it to blood alcohol levels.
Return to Top
ARSON / EXPLOSIVES
Arson investigation is the science of
determining the cause of a fire. It is necessary for experts in this field to
be knowledgeable in scientific, as well as non-scientific areas. Such
scientific areas include physics, chemistry, and electronics. An extensive
knowledge of the construction of buildings would be an example of a
non-scientific area. It is also important for an arson investigator to be
aware of the psychological disorders that are related to fire-setting
behavior.
Investigation of explosives is similar
since the explosion scene requires extensive reconstruction efforts. The
investigator must be knowledgeable in the areas of manufacture, materials, and
detonation of explosive materials. Another important aspect is the knowledge
of the mental states and psychological disorders that lead to random and
intentional bombings.
Return to Top
CRIME SCENE INVESTIGATION
/ RECONSTRUCTION
Crime Scene Investigation deals with the preservation and collection of evidence located
at the scene of a crime. Crime Scene
Reconstruction is the interpretation of the
evidence to recreate the circumstances of the crime. Each crime scene is
unique and must be evaluated individually.
Return to Top
DNA/SEROLOGY
Serology is the study of body fluids:
blood, saliva, semen, and urine.
From biological evidence left at a crime scene, such as hair or semen,
DNA analysis (or
DNA typing) can
be used to identify an individual. The most widely used methods of DNA typing
are Restriction Fragment Length
Polymorphism (RFLP) and Polymerase Chain Reaction
(PCR).
The RFLP process is a long, labor
intensive procedure that involves extracting DNA from the biological sample, fragmenting the
DNA with special (restriction) enzymes and
separating the molecular pieces by gel electrophoresis.
PCR is a technique by which a miniscule
and/or degraded amount of DNA can be quickly
amplified. This is beneficial in cases where only small quantities of evidence
are discovered.
Return to Top
DRUG IDENTIFICATION / TOXICOLOGY
Toxicology is the study of substances
that are harmful to humans. Toxicologists examine body fluids and organs for
the presence of poisons, alcohol, and drugs. A toxicologist detects,
identifies, and quantifies minute amounts of these substances for further
evaluation.
Return to Top
FIREARMS / TOOLMARKS IDENTIFICATION
The basic principle of firearms
examination is based on the fact that most machined parts will have
unique marks, which can be transfered to other surfaces. Almost all gun
barrels, as well as the machined areas in the weapon's firing mechanism, leave
unique marks on bullets fired through the barrel and on cartridge cases worked
through the firearm. A firearms examiner deals with the analysis of both
firearms and ammunition of all types. The Firearms
Examiner also determines whether a bullet originated from a suspect
firearm. Impacted items which were on the receiving end of a discharged bullet
are also examined for discharge residues in an attempt to ascertain muzzle
distance.
As each machined gun barrel is unique, so too are all machined tools.
These tools leave distinct marks on most objects they contact. A toolmark is
any machined impression transfer caused by the tool coming into contact with
an object. A toolmark examiner compares
toolmarks in order to determine what type of tool, or what exact tool, was
used to make a specific mark.
Return to Top
LATENT PRINTS
A latent print expert examines all types
of fingerprints found at a crime scene, whether visable or not. The three
categories of fingerprints include: latent, plastic, and contaminated.
Latent fingerprints are the invisible prints
made by the deposit of oils or perspiration from the friction ridges of one's
fingers onto another substance. Plastic prints are those fingerprints
impressed into easily malleable surfaces -- like plasticine or putty.
Contaminated fingerprints are the result of material transfers, such as
liquid blood, from the fingers to a surface.
Return to Top
QUESTIONED DOCUMENTS
A Questioned Documents Examiner analyzes
and identifies written, printed, or typed material for authenticity. If the
authenticity is doubted or if its source is unknown, it becomes a Questioned Document. Questioned
Document examination may be associated with criminal cases involving
forgery, suicide, and embezzlement.
Return to Top
TRACE EVIDENCE
Examples of trace
evidence could be hair, fibers, paint chips,
glass fragments, etc. Trace
evidence is often of such a minute nature that
it can be easily cross-transfered from one surface to another without
detection; therefore, the microscope is usually the first tool used in its
examination and identification. Instrumental methods of analysis are generally
the second phase of comparison associated with trace evidence.
Return to Top
|
