Реферат: Forensic Science Essay Research Paper Forensic Science
Forensic Science Essay, Research Paper
Forensic Science, also known as Forensics, is the application of
science to law. It uses highly developed technology to uncover scientific
evidence in a variety of fields. Modern forensic science has a broad range of
applications. It is used in civil cases such as forgeries, fraud or negligence.
The most common use of forensic science is to investigate criminal cases
involving a victim, such as assault, robbery, kidnapping, rape, or murder.
Forensic science is also 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 a country
is developing a secret nuclear weapons program. 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 can also determine whether drinking water meets legal
The medical examiner is the most important individual in an
investigation of a crime involving a victim. It is the responsibility of the
medical examiner to visit the crime scene, conduct an autopsy (examination
of the body) in cases of death, examine the medical evidence and lab reports,
study the victims history, and put all the information together in a report to be
turned in to the district attorney.
Medical examiners are usually physicians specializing in forensic
pathology, the study of structural and functional changes in the body as a
result of injury. Their training and qualifications most often include a medical
degree and an apprenticeship in a medical examiners office.
In the field of forensic science, there are many subspecialties. They
include odontology (the study of teeth), anthropology(the study of human
beings), psychiatry, biology, chemistry, physics, toxicology (the study of
poisons), and pathology (the examination of body tissues and fluids). The
medical examiner may call upon forensic scientists who are specialized in
these fields for help in a crime investigation.
Toxicology is a branch of forensic science that deals with the adverse
effects of drugs and poisonous chemicals found in the home, at work or in the
environment. All drugs have toxic effect but the effect is most often minor.
The toxic effect of drugs may produce only a little discomfort or they may be
serious enough to cause death. One of the most common cases of death by
poison is arsenic poison.
Pathology is the branch of forensic science that determines the nature
and course of diseases by analyzing body fluids and tissues. Pathology is
divided into clinical and anatomic pathology. Clinical pathologists contribute
to the diagnosis of diseases by measuring chemicals and cells in blood,
sputum, bone marrow and urine. Anatomic pathologists perform autopsies
and analyze tissues taken from patients during surgery or by biopsy.
The medical examiner investigates many different types of violent
crime to determine whether a violent death was an accident, a suicide, or a
homicide. In cases involving gunshot wounds, the medical examiner looks for
gunpowder residues on the clothing of the victim and around wounds. The
information is used to determine whether the gun was fired by the victim of
by someone else.
In the case of knife wounds, the medical examiner must distinguish
between a cut (an injury that is longer than deep) and a stab wound (an injury
that is deeper than long).He must also be able to identify a defense wound
which is a cut caused when a victim grabs the knife in self-defense. Cuts are
associated with suicide. The body of the victim usually has numerous parallel
cuts which indicate hesitant wounds or repeated hesitant trials before the final
cut is made. Homicides typically consist of one deep gash.
Medical examiners are also called upon to investigate cases of
asphyxiation or death form lack of oxygen in the blood. Asphyxiation may be
caused in a number of different ways, such as hanging, which can be an
accident, homicide or suicide, or strangling which is homicide. Damage to the
victims air passage by an object in the throat or compression of a victims
chest by a person or an objector the replacement of oxygen in the red blood
cells by another gas such as carbon monoxide poisoning. That too can be a
result of an accident, homicide or suicide.
In a death involving carbon monoxide poisoning a closed garage door
and no marks on the body are usually taken as an indication of suicide. The
presence of tools around the car and grease on the victims hands is an
indication of an accidental death. The presence of a wound caused by a blow
to the head or if there is no carbon monoxide in the blood of he victim
indicates a homicide that was made to look like a suicide.
Forensic science uses sophisticated lab techniques to detect the
presence of substances in the victim, the suspected criminal, or at the crime
scene. In determining whether alcohol was involved in a crime, the amount of
alcohol in the blood can be measured in two ways. The first is to measure the
amount of alcohol exhaled in the breath of the person. This reveals the
concentration of alcohol in the person s blood. Blood alcohol level can also
be determined by blood tests, usually through chromatography. In this
method, the blood sample is vaporized by high temperature, and the gas is
sent through a column that separates the different chemical compounds
present in the blood. Gas chromatology also detects the presence of
barbiturates, cocaine, amphetamines, and heroin.
When a body is discovered in a lake, stream, river or ocean, and the
lungs are filled with water, the medical examiner must determine if the
drowning occurred where the body was found or somewhere else. A
standard microscope that can magnify objects to 1500 times their size is used
to look for diatoms. Diatoms are single cell algae that are found in all natural
bodies of water. If there are no diatoms, it can be concluded that the
drowning took place in a bathtub or sink since diatoms are filtered from tap
A scanning electron microscope that can magnify objects 100,000
times is used to detect tiny gunpowder particles present on he hand of a
person who recently fired a gun.
One of the oldest techniques of forensic science is dusting the scene of
a crime for fingerprints. In one method of obtaining a fingerprint, a technician
spreads fine powder over a surface with a brush or magnetic wand. The
powder sticks o proteins secreted by the sweat glands on the skin ridges of
the fingertip When the excess powder is removed, an outline of the contours
of the ridges remains. The print may also be chemically treated to reveal the
contours. Since no two fingerprints are the same, fingerprinting is a positive
way of identifying someone.
Other evidence that may be found at a crime scene is blood, hair, skin,
or semen. Human bite marks can also serve as evidence. Bites can be found
on the victims body or in pieces of food or gum found at the crime scene. A
forensic scientist can fill the impression caused by the bite marks with a liquid
plastic. The cast will form an accurate replica of the assailants teeth which is
then compared with a cast of the suspects teeth.
District attorneys call forensic scientists to give their expert testimony
in a trial concerning what they find from an autopsy and what they write in
the lab reports. Expert testimony is the statement given by a specialist who
has been recognized as having expert knowledge about evidence in the case.
An expert witness is allowed to give an opinion about whether or not the
evidence is valid. An expert witness may also quote the statements of other
experts to support an opinion. Ordinary witnesses are restricted to giving
statements about what they actually saw or heard.
The medical and legal approach to dealing with crimes began in
England during the 12th century. King Richard I established the Office of the
Coroner. The coroners main job was to keep a record of all criminal affairs in
the county and investigate all deaths that were believed to be a homicide or
suicide. The need for more scientific investigation of unnatural deaths became
evident and the coroners began asking doctors for help. Over time medical
schools started to prepare doctors in that specific field. In 1807, the
University of Edinburgh in Scotland instituted a Department of Legal
Early American colonists Bought the coroner system with them. As
medical involvement in investigating violent and unexplained deaths
increased, communities began requiring that coroners have specific academic
training. In 1877, Massachusetts replaced the coroners office with the Office
of the Medical Examiner, which was to be headed by a physician. Soon many
other states followed. In 1915 New York City established a program where
the medical examiner was authorized to investigate all deaths that occurred to
people who appeared to be in good health, that resulted from criminal
violence, accidents, or suicides.
Computer technology now allows law enforcement officers o record
fingerprints digitally and to transmit and receive information for quick
identification. Recent developments in technology allows scientists o examine
the deoxyribonucleic acid (DNA) or genetic material of blood, hair, skin, or
semen to see if they belong to the victim or the suspected criminal. Using
polymerase chain reaction (PCR), a lab can clone the DNA from a very small
sample of one of those substances.
Forensic science as practiced today is a field of science medicine that uses
electron microscopes, lasers, ultraviolet and infrared light, advanced chemical
techniques and computerized databanks to analyze and research evidence.