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Introducing Forensic Science
At most crime scenes, the first step is to secure the evidence by pre-
venting people from trampling it. Normally the first-responders to the
scene, the police, handle this. The ECU is responsible for carefully and
methodically analyzing the crime scene, looking for as much evidence as
possible. Typically, the scene will be divided into a grid—the most efficient
and thorough method for finding evidence. Once the grid is established,
the crime scene is sketched and photographed so each piece of evidence
that is collected can be linked to its proper location at the scene. These
photographs often serve as evidence themselves. As evidence is collected,
it is bagged, tagged, and labeled with the proper grid location. One of
the most critical steps in evidence collection is the “chain of custody.”
Every piece of evidence must be handled in accordance with the rules
of the chain of custody, which require that each person who handles the
evidence signs for it before he can take possession of it. A break in the
chain of custody can be enough for a judge to disallow the use of a piece
of evidence in a trial—something for which no forensics expert wants to
be responsible.
Collected evidence is cataloged and sent to the proper department
at the crime laboratory for processing. Specialists who work only with
particular evidence types staff each department. Each evidence type has
its own specialized department in order to reduce errors and obtain the
maximum amount of information each bit can provide. The evidence is
examined exhaustively as every single bit of information can be crucial
to the case at hand. One mistake can be enough to allow a criminal to
walk free. Because of the importance of their work, forensic experts are
required to train long hours in the laboratory before they are allowed to
work alone.
When physics is applied to forensics, experts will rely on various types
of physical evidence—such as blood spatter, bullets, and wounds—as well
