Page 190 - Automated Fingerprint Identification Systems (AFIS)

STANDARDS AND INTEROPERABILITY 175

8.5.1.2 Who Lifts the Latent Prints at the Crime Scene?
Imagine the evidence technicians in their white protective suits combing a
crime scene looking for every piece of evidence, including hair and blood
(DNA), fibers (lab), and latent fingerprints (AFIS). Does every local police
department have this technology, investment in personnel and equipment, and
sophisticated laboratory? Probably not. What a typical department most likely
has are trained evidence technicians, crime scene investigators, or others,
perhaps some with latent fingerprint training, who know what to look for and
what to discard. Or perhaps they have officers trained in the preservation of
evidence who are taught to bring back to the office anything that looks like
evidence.
Personnel trained in fingerprint identification who work a crime scene have
the experience to look at an image and decide if it is “of value,” i.e., if there is
sufficient ridge structure to effect a positive identification. With this knowledge,
a crime scene technician trained in fingerprints from Agency A may discard
finger images that are of “no value” and, alternatively, see ridge structure in
what might appear to the untrained eye as merely a smudge. The technician
without fingerprint training from Agency B, however, collects every piece of evi-
dence he or she can find, with the notion that it will be sorted out later. In
some departments, the crime scene specialist is also the fingerprint expert and
so knows exactly what to look for and how to process the latent print images.
Figure 8.1 describes two of many decisions that affect the statistical reporting
of latent print identification. It shows how two agencies with competent staff
process a total of 100 latent prints found at ten crime scenes.
In this example, there are ten identical crime scenes investigated by two
evidence collectors; one, a crime scene specialist at Agency A who has latent

Figure 8.1
100
Crime scene Latent Prints from Crime
prints Scene
from 10 cases

Agency A Agency B

“No value” Specialist “No value”
Yes No
prints excluded; trained in prints included;
80 prints kept latent 100 prints kept
8 cases prints? 10 cases

100 lifts at crime scene 100 lifts at crime scene
20 of no value, 80 of value No value determination made
80 lifts taken to headquarters 100 lifts taken to headquarters