8127/frame/fm

 
a.
Trace Evidence — Transfer of Very Small Physical Entities
Locard was particularly concerned with the transfer of trace materials, such
as dust, dirt, and grime (1920; 1923; 1928; 1930; 1931–1940). In today’s crime
laboratory, typical trace evidence includes hairs, fibers, paint, soil, and other
materials that make up the world. Trace evidence is typically characterized
by the need for a microscope to characterize the material adequately, even if
it can be seen by the unaided eye. These are the materials that Locard felt
were most important in forensic science because the criminal would not be
aware that such materials would be transferred.
 
b.
Macroscopic Evidence — Transfer of Larger Physical Entities
Because the concept of transfer arose through the study of dusts and other
microscopic material, we are used to thinking about transfer only on a
microscopic scale. In fact, it is inordinately useful to consider transfer on a
macroscopic scale as well. Because it is impossible to draw an arbitrary line
between microscopic evidence and that which is easily visible to the naked
eye, we will take the liberty of creating the term “macro-transfer” to describe
this situation.
Much physical match evidence falls into this category. For instance, the
scrap of paper used to write the ransom note is only one half of the original
intact piece, the other half of which is still in the kidnapper’s pocket. Broken
glass fragments are another example of this type of evidence.
 
c.
Factors Affecting Transfer and Detection
Several factors either promote or inhibit transfer of materials. These influence
both our ability to detect crime-related materials (i.e., evidence) and our
interpretation of the analytical findings. These components must be consid-
ered when assessing the strength and significance of an association:
• The 
 
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