Criminalistics (page 2)
Scope of Work
Criminalists analyze, compare, identify, and interpret physical
evidence. Forensic labs have two primary functions: identifying
evidence, and linking suspect, victim, and crime scene through
physical evidence. The main role of the criminalist is to
objectively apply the techniques of the physical and natural
sciences to examine physical evidence. Physical evidence
may be anything: evidence so small that a microscope is
needed to see it, or as large as a truck. It may be as subtle
as a whiff of a flammable gas at an arson scene or as obvious
as a pool of blood at a homicide scene. The enormous range
of material challenges the ingenuity of the criminalist
who examines and identifies hair, fibers, blood, seminal
and body fluid stains, alcohol, drugs, paint, glass, botanicals,
soil, flammables, and safe insulating material; restores
smeared or smudged markings; and identifies firearms and
compares bullets, tool markings, and foot prints. In most
cases, the amount of the evidence to be tested is very small,
such as a drop of blood, a hair, or a piece of glass.
Using analytical skill and practical experience, the criminalist
separates important evidence from that having little or
no value. Next, the criminalist sorts, compares, and identifies
the evidence, using chemicals and instruments, developing
useful information for an investigation or trial. He may
find, for example, that a bullet has been fired from a particular
gun, the blood in the suspect's car is from the victim,
or that a fragment of plastic from the scene of a hit-and-run
accident has broken off a particular car. These types of
analyses are difficult; they require an eye for detail,
a broad practical scientific background, and the ability
to apply these skills in the laboratory.
Scientist in forensic laboratory keeping
the
bench area meticulously clean.
Forensic scientist microscopically
examining evidence.
Perhaps the most important task of the criminalist lies
in interpreting the results of the tests to determine the
truth. This may be the circumstances at the time a crime
occurred, or may support a witness' statement. Reconstructing
the events of a crime is often very difficult. It requires
an understanding of human behavior, of the physical laws
and processes involved, and the recognition of how they
interact. Finally, any findings must be conveyed to the
other parts of the criminal justice system, such as officers
and attorneys. This is done by written reports and expert
testimony. The criminalist must express conclusions so that
technical details are understood by the non-scientist jury,
attorneys, and judges.
Trace Analytical System used to examine
evidence.
