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2.
Individualization
a.
Biological Evidence
The concept of individualization is clearly central to the consideration of
physical evidence. Even before it was formally articulated, it seems impossible
that the early civilizations who used fingerprints and other biometric mea-
surements did not presume their uniqueness to an individual. Adolphe
Quetelet, the Belgian statistician who provided the foundation for Bertillon’s
work, may have been the first to express formally the inherent assumption
that no two human bodies are exactly alike (Thorwald, 1964; Block, 1979).
Bertillon, of course, created the first systematized knowledge base for per-
sonal identification. He even attempted to provide a statistical foundation
for his conclusions. Bertillon suggested that if 14 proscribed measurements
were taken, the chances of any two individuals having exactly the same
measurements were 268,435,456 to 1 (Thorwald, 1964).* This was based on
Quetelet’s (unproven) assumption that each measurement would decrease
the frequency of the total profile by 1/4. Whether or not a mathematical basis
existed for this calculation, it was certainly one of the first allusions (illu-
sions?) to the potential multiplicative value of added traits. Never mind that
* Thorwald (pg. 10), reports this number as 2
86
,435,456 to 1. We can hope the transposition
of digits occurred in Thorwald’s transcription of the data rather than in the original source.
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Principles and Practice of Criminalistics
Bertillon apparently failed to account for any possible dependence of anthro-
pometric traits on each other.
As soon as fingerprints replaced anthropometry, they became the stan-
dard of individuality against which every other kind of physical evidence was
measured. Even today, when someone wants to tout the power of some