Page 192 - Automated Fingerprint Identification Systems (AFIS)

STANDARDS AND INTEROPERABILITY 177

elimination prints is no less than the expertise required to make any latent print
identification.
In Figure 8.2, the effect of taking elimination prints is highlighted. Agency
A takes elimination prints at the crime scene, but Agency B does not. When the
technicians from Agency A return to headquarters, they make a manual com-
parison of the 80 prints they have taken with the elimination prints. They make
20 identifications without the use of the AFIS system. They close two cases with
these identifications, i.e., in two of the ten cases, the only latent prints found
at the crime scene were identified as belonging to persons who had a legitimate
reason for being there. Of the original 100 images the technicians examined
at ten crime scenes, 20 were determined to be of no value. Assume these 20
represented all the images in two cases. The elimination prints identified
another 20 latents and closed two additional cases from further latent print
searches. At this point, the team from Agency A has 60 latent images remain-
ing from six cases. The technicians at Agency B did not take elimination prints
from anyone present at the crime scene. They still have 100 latent prints taken
from ten crime scenes.
If asked for a statistical report at this time, the staff at Agency A could report
that they made identifications on 20 out of 80 latent prints (100 images minus
20 images of no value) in eight cases, a hit rate of 25% before any AFIS searches.
Agency B has 100 latent images, value undetermined, and has not taken any
elimination prints. Their hit rate for 100 images thus far is zero.
As illustrated in Figure 8.3, when the teams from the two agencies return to
their headquarters, each team has a different number of images from the crime
scene to search. The team from Agency A has 60 images, while the team from
Agency B has 100. With the computer imaging equipment available, the team
from Agency A determines that only 50 of the 60 latent images are of value;
similarly, Agency B eliminates 30 of the 100 latent images, leaving 70 latent
images for them to search.

Figure 8.2
Elimination
Prints Use of Elimination Prints

Agency A Agency B
Manual
comparisons Yes Taken at No All 100 prints may
identify 20 prints scene? be searched on
6 cases AFIS, 10 cases

Elimination prints identify 20 No elimination prints taken
60 lifts remain 100 lifts remain