8127/frame/fm

 
I–
DENTICAL!.
 
—Jim Trotter III
 
D.A. in the movie My Cousin Vinnie, played by Lane Smith
 
A.
The Relationship of Evidence to Source
In 
 
Crime Investigation
(1953), Kirk suggests that the central task of the crim-
inal investigator is to establish personal identity. He continues to say that
supplementary to this task is the identification of physical objects that may,
in turn, contribute to the desired personal identification. Kirk outlines the
issues and difficulties inherent in the endeavor to establish personal identity
through clues provided by physical evidence. In this chapter, we continue
that discussion.
In Chapter 3 we introduced the concept that identification and individ-
ualization are each legitimate goals in a forensic analysis. Historically, the
word 
 
identification
has had two meanings: one dealt with defining the nature
of a substance, while another implied the failure to individualize. We think
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Classification, Identification, and Individualization
115
that each meaning is an important concept in forensic science and so have
adopted two words to communicate these separate intentions. While
acknowledging that in some instances usage may indeed overlap, we offer
the following definitions:
 
Identification
: Defining the physicochemical nature of an evidence item
(without a specific reference item).
 
Classification
: Inferring multiple potential common sources for an evi-
dence item.
 
Individualization
: Concluding a singular common source for two items.
Because the objective of identification defines an end point in and of
itself, we depict this route as a bifurcation from the path leading to individ-
ualization (Figure 3.2). Both identification and individualization are concepts
essential to the practice of criminalistics. Which of the two is invoked depends
on the legal question as well as the attributes of the evidence. Classification,
on the other hand, becomes an end point by default rather than by design.
We set out with a goal to individualize and because of some limitation
imposed by either the evidence or the test, we fail to narrow the source item
to a category of one. Although we may not succeed in individualizing, we
can restrict the category to which the evidence belongs and define the char-
acteristics of items in that category. This results in classification.
In this chapter we address that aspect of forensic science that virtually
defines it, the process of comparing an evidence and reference sample and
forming a conclusion about their relationship. We start with classification —
a process that either results in identification or proceeds to individualization —
then continue with identification, the unrecognized hero of the criminal
justice system. We conclude with a discussion of individualization. But first,
we make a brief digression to discuss a couple of themes common to any
forensic comparison.