Page 88 - Automated Fingerprint Identification Systems (AFIS)

CHAPTER 4

AFIS SUMMAR Y—
HOW THE SYSTEM WORKS

This chapter provides an overview of how Automated Fingerprint Identification
Systems work through the interaction of various processing and databases.
The chapter also notes some of the differences in tenprint versus latent
print processing. Latent print processing includes not only a search of the
latent print against the latent cognizant database, but also the search of
new latent cognizant records against the unsolved latents. If desirable, an
unsolved latent print can be searched against to the unsolved latents to iden-
tify a serial offender, if that person’s identity is unknown. Also noted in this
chapter are some of the changes to the identification business model that AFIS
has introduced.

4.1 DATABASES
Identification systems may contain databases of one, two, three, or more
records. Examples of these databases include the tenprint database, which con-
tains information on two fingers; the latent cognizant database, which contains
information on all ten fingers; and the unsolved latent database, which is the
repository for latent print images not identified on AFIS. The tenprint and
latent cognizant databases may contain millions of records, while the unsolved
latent database may contain hundreds of thousands of records. Each database
may be further segmented into an image, a matcher, and possibly an alpha data-
base. Figure 4.1 shows an illustration of these databases.
The Computerized Criminal History (CCH) database contains information
about the subject’s activity for fingerprintable events. Although the term crim-
inal history implies that only criminal activity is recorded, this is not always the
case; any fingerprintable event is recorded in this database. For example, job
applicants who have been fingerprinted as part of a background check have a
history stored in this database. That history, or rap sheet, includes the date when
the person was fingerprinted, the person’s name and other biographical infor-
mation, aliases, if any, and other identification information.