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5.
Impression Evidence — Does Divisible Matter Apply?
Divisible matter does not account for a large category of evidence, that of
pattern transfer evidence, such as prints and impressions. Although small
amounts of physical matter may be transferred, it is the pattern of transfer
that concerns us, not the substance. Therefore divisible matter does not apply.
The transfer of matter requires its prior division; the transfer of 
 
traits
may not.
 
D.
Transfer Theory (Locard)
Once matter has divided, it is “available” for transfer. Two different excerpts
from Locard’s writing* provide slightly different insights into his thinking
on the issue of material transfer.
* Translation courtesy of Sharon Kruzik.
1.
 
Il est impossible au malfaiteur d’agir, et sourtout d’agir avec l’intensite
que suppose l’action criminelle sans laisser des traces de son passage.
(1920)
It is impossible for the criminal to act, and especially to act with
the force that a crime demands, without leaving behind traces of
his presence.
2.
 
Nul ne peut agir avec l’intensite que suppose l’action sans laisser des
marques multiples de son passage, tantot le malfaiteur a laissi sur les
lieux des marques de son activiti, tanto par une action inverse, il a
emporti sur son corps ou sur ses vetements les indices de son sejour
ou de son geste.
(1923)
No one can act (commit a crime) with the force (intensity) that
the criminal act requires without leaving behind numerous signs
(marks) of it; either the wrong-doer (felon, malefactor, offender)
has left signs at the scene of the crime, or on the other hand, has
taken away with him — on his person (body) or clothes — indi-
cations of where he has been or what he has done.
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Principles and Practice of Criminalistics
As much as the Locard transfer theory has been invoked, no peer-reviewed
literature exists that proffers it, tests it, or refutes it. It is axiomatic in forensic
science; it is accepted as true without proof.
The second of the two quotes above is a more complete explication of
Locard’s sense of what happens during the commission of a crime. For
example, he talks about transfer of material both from the criminal to the
scene, as well as from the scene to the criminal. Significantly, this passage
has been taken to mean that when two objects come in contact, material will
be transferred in both directions 
 
between the two objects.
That does not appear
to be the plain reading of this translation. It is possible to interpret this
passage to mean that different kinds of material may be transferred from the
criminal to the surroundings, 
 
or
from the surroundings to the criminal;
carpet fibers may accumulate on the shoes of a criminal, yet there may be
no trace of his on the carpet.
For a maxim that has been accepted as the lynchpin of forensic science
for over 80 years, it is curious that no one has ever tested this theory by trying
to falsify it. Of course, if it were completely false, then no physical evidence
would exist to examine. Not wanting to tackle the disputatious “
 
Il est impos-
sible…
,” we can say as a matter of common observation that at least some of
the time, contact between two objects results in the transfer of material from
one to the other. We leave as a challenge to the profession of forensic science
to begin the process of testing this working hypothesis.