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FORENSIC SCIENCE
Forensic science is the application of a broad spectrum of sciences
to answer questions of interest to the legal system. Forensic science
uses highly developed technologies to uncover scientific evidence
in a variety of fields. The word forensic comes from the Latin word
forensis (meaning “public”) and currently means “used
in or suitable to courts of judicature or to public discussion or
debate.” Forensic science is science used in public, in a court
or in the justice system; so any science, used for the purposes of
the law, is a forensic science.
The Eureka legend of Archimedes (287
to 212 B.C.E.) can be considered an early account of the use of forensic
science. By examining the principles of water displacement, Archimedes
was able to prove that a crown was not made of gold (as it had been
claimed) by its density and buoyancy. The use of fingerprints as
a means to establish identity occurred during the seventh century.
The use of medical evidence to determine the mode of death began
as early as the 11th century in China and flourished in 16th-century
Europe. The combination of a medical and legal approach to dealing
with crimes used in the United States today had its origin in England
in the 12th century, when King Richard I established the Office of
the Coroner. The American colonists instituted the coroner system,
which still exists today. There is no federal law requiring a coroner
to be a licensed physician.
Modern forensic science has a broad range
of applications. It is used in civil cases such as forgeries, fraud
or negligence. It can help law enforcement officials determine whether
any laws or regulations have been violated in the marketing of foods
and drinks, the manufacture of medicines or the use of pesticides
on crops. It also can determine whether automobile emissions are
within a permissible level and whether drinking water meets legal
purity requirements. Forensic science is used in monitoring the compliance
of various countries with such international agreements as the Nuclear
Non-Proliferation Treaty and the Chemical Weapons Convention and
to learn whether countries are developing secret nuclear weapons
programs. However, forensic science most commonly is used to investigate
criminal cases involving a victim, such as assault, robbery, kidnapping,
rape or murder.
The medical examiner is the central figure in an investigation
of crimes involving victims. It is the responsibility of the medical
examiner to visit the crime scene, conduct an autopsy (an examination
of the body) in cases of death, examine the medical evidence and
laboratory reports, study the victim's medical history and put all
that information together in a report to the district
attorney, the
public prosecuting officer within a defined district. Medical examiners
usually are physicians specializing in forensic pathology, the study
of structural and functional changes in the body as a result of injury.
The
medical examiner may call upon forensic scientists, who are specialists
in these various fields for help investigating a crime. In criminal
cases, forensic scientists often are involved in the search for and
examination of physical traces that may be useful for establishing
or excluding an association between someone suspected of committing
a crime and the scene of the crime or victim. Such traces commonly
include blood, other body fluids, hair, textile fibers from clothing,
paint, glass, other building materials, footwear, tool and tire marks
and flammable substances used to start fires. Sometimes the scientist
will visit the scene itself to advise about the likely sequence of
events and to join in the initial search for evidence. Other forensic
scientists called toxicologists analyze a person’s bodily fluids,
tissue and organs for drugs, poisons, alcohol and other substances.
Yet others specialize in firearms, explosives or documents whose
authenticity is questioned.
One of the oldest techniques of forensic
science is dusting the scene of a crime for fingerprints. Because
no two fingerprints are the same, fingerprinting provides a positive
means of identification. Computer technology now allows law enforcement
officers to record fingerprints digitally and to transmit and receive
fingerprint information electronically for rapid identification.
DNA
fingerprinting provides an excellent way to analyze blood, hair,
skin or semen evidence found at the crime scene. By using an advanced
technology method known as the polymerase chain
reaction (PCR), a
laboratory rapidly can clone, or multiply, the DNA from a tiny sample
of any of these substances. This process produces enough DNA to compare
with a sample of DNA taken from a suspected criminal.
Forensic science
today is a high-technology field using electron microscopes, lasers,
ultraviolet and infrared light, advanced analytical chemical techniques
and computerized databanks to analyze and research evidence. For
example, blood-alcohol levels can be determined by actual blood tests,
usually through gas chromatography. In this method,
the blood sample is vaporized by high temperature and the gas is
sent through a column that separates the various chemical compounds
present in the blood. Gas chromatography permits the detection not
only of alcohol but also of other drugs, such as barbiturates, cocaine,
amphetamines and heroin.
When a body is discovered in a lake, stream,
river or ocean and the lungs are found to be filled with water, the
medical examiner must determine if the drowning occurred where the
body was found or elsewhere. A standard microscope that can magnify
objects to 1,500 times their actual size is used to look for the
presence or absence of diatoms, single-celled algae
that are found in all natural bodies of water. The absence of diatoms
raises the possibility that the drowning took place in a sink or
bathtub, not where the body was found, since diatoms are filtered
from household water during treatment.
A scanning electron microscope that can
magnify objects 100,000 times is used to detect the minute gunpowder
particles present on the hand of a person who recently has fired
a gun. These particles also can be analyzed chemically to identify
their origin from a particular type of bullet. Forensic examination
of substances found at a crime scene often can establish the presence
of the suspect at the scene.
Human bite marks also can serve as circumstantial
evidence. Such bites may be found upon the body of a homicide victim
or within pieces of food or other objects found at the crime scene,
such as chewing gum. A forensic scientist can fill the impressions
caused by these bites with liquid plastic. Upon hardening, the cast
formed is an extremely accurate replica of the assailant’s
teeth, which can be compared with a cast made from the teeth of the
suspect.
Subdisciplines of Forensic Science
Criminalistics: This is the application
of various sciences to answer questions relating to the examination
and comparison of biological evidence, trace evidence, impression
evidence (such as fingerprints, shoeprints and tire tracks), controlled
substances and firearms in criminal investigations.
Forensic accounting: This is the study and interpretation of financial evidence.
Forensic
anthropology: This is the application of physical anthropology in
a legal setting, usually for the recovery and identification of skeletonized
human remains.
Forensic economics: This is the study
and interpretation of economic damage evidence to include present-day
calculations of lost earnings and benefits, the lost value of a business,
lost business profits, lost value of household service, replacement
labor costs and future medical care costs.
Forensic engineering: This
is the study of the causes of failure of devices, vehicles and structures.
Forensic
entomology: This deals with the examination of insects in,
on and around human remains to assist in determination of time or
location of death. It also is possible to determine if a body has
been moved after death.
Forensic odontology: This the study of the
uniqueness of teeth.
Forensic psychology and forensic psychiatry: These deal with the legal aspects of human behavior.
Forensic ballistics: This is the science dealing with the investigation of use of firearms
and ammunition.
Wildlife forensics: This is the study
of crime scenes when the victim is an animal, such as an endangered
species or an animal illegally hunted or poached.
Forensic scientists
work in laboratories, at crime scenes, in offices and in morgues.
They may work for federal, state and local government, forensic laboratories,
medical examiners offices, hospitals, universities, toxicology laboratories,
police departments, medical examiner/coroner’s
offices or as independent forensic science consultants. The minimum
requirement is a bachelor’s degree in chemistry, biology, physics,
molecular biology or a related science.
Related Links
http://www.aafs.org
American Academy of Forensic Sciences
http://www.aafs.org/default.asp?section_id=resources&page_id=choosing_a_career#Criminalistics
Choosing a Career, American Academy of Forensic Sciences
http://www.aafs.org/default.asp?section_id=resources&page_id=colleges_and_universities
Education Opportunities, American Academy of Forensic Sciences
http://www.aafs.org/yfsf/index.htm
Young Forensic Science Forum, American Academy of Forensic Sciences
http://www.beginnersforensics.bravehost.com
Forensic Science Central
http://www.forensic-science-society.org.uk/information/careers.html
A Career in Forensic Science, The Forensic Science Society
http://school.discovery.com/lessonplans/forensics.html
Forensic Science lesson plans, DiscoverySchool.com
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