16
Principles and Practice of Criminalistics
to proceed. In this setting, the only germane questions are the legal questions.
The role of the forensic scientist is to translate the relevant legal question
into a scientific question. If this cannot be done, then
forensic science has
no role to play.
One way the criminalist can assist law enforcement and legal profession-
als is by helping them to translate a legal question correctly (Did O. J.
Simpson kill Ron Goldman and Nicole Brown Simpson?) into a question
that science can answer (What genetic types are found in the bloodstains
from the scene?). The answer to the scientific question will then assist in
answering the legal question. Conversely, one of the most effective counters
to the presentation of physical evidence is to show that the wrong question
was asked. For instance, finding the suspect’s blood on the suspect’s shoes
is irrelevant to whether he attacked the victim. Similarly, the finding of an
unusual collection of fibers on the murder weapon
becomes meaningless if
both the suspect and the victim were wearing uniforms composed of the
rare fiber set. Analysis of physical evidence in a crime laboratory is best
suited to answering
who
,
what
,
where
, and
how
; it is less adept at answering
when
and can almost never answer
why
. Because the design or selection of
appropriate tests depends completely on the initial hypothesis, it must be
carefully framed at the beginning of the investigation rather than on the
witness stand.
It is crucial to note that the moment the
question is translated into
science, the component of guilt or innocence is lost. Forensic science seeks
to establish connections (or lack thereof) between evidence and its source,
and secondarily, between items that may be associated by the evidence. Said
in another way, we consider the probability of the evidence in light of com-
peting hypotheses, often the prosecution’s allegation and the defense prop-
osition. Guilt or innocence may only be considered
by the legal system and
decided by a judge or jury.
The focus of an analysis and its interpretation are dictated by the cir-
cumstances of the case and the question(s) facing the criminal justice system.
This is the reason the most common and useful answer to any general crim-
inalistics question is, “it depends.” The analysis of a sexual assault case serves
as a good example of this point. Sexual assault, and rape in particular, is
distinguished from other crimes in that it is not necessarily evident by mere
observation that a crime has occurred. We know that if we come home, the
window has
been forced open, and our stereo is missing, that a burglary has
taken place. This is generally obvious to any other observer as well. It is rarely
possible to look at a woman or man and determine that she or he has been
raped. The crime of rape can be summarized as the act of sexual intercourse
accomplished through fear or force. Science can assist in substantiating one
of the elements (that of sexual intercourse) by determining that sperm are
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Introduction
17
present. This, of course, says nothing about the fear or force part. The mean-
ing of the scientific finding may change dramatically
depending on the cir-
cumstances of the case.
The use of science in the arena of civil law has grown as pioneering and
developing societies have achieved the economic stability necessary to sup-
port elective activities. Civil litigation almost always concerns money; to
argue about it, one must have both the time and means to do so. Many of
the common areas of civil litigation, such as medical malpractice, money
fraud, and engineering, are outside the scope of this volume. Of the
areas of
inquiry shared by criminal and civil investigations, the legal standards obvi-
ously differ, leading to, among other things, different questions, but the
scientific analyses remain the same.
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