Page 196 - Automated Fingerprint Identification Systems (AFIS)

STANDARDS AND INTEROPERABILITY 181

8.5.2.2 Was the Best Card Selected for Conversion?
It may seem like this is a question that does not need to be asked, but it must.
In an earlier discussion, it was noted that a criminal record may contain several
events, e.g., arrests, each of which may be associated with a fingerprint capture.
If a person had been arrested only once, there would only be one tenprint card
in the master fingerprint file. If that person had been arrested more than once,
there would be several sets of finger images of the same person in the file, and
the finger images on each card would not necessarily be identical. Conditions
such as finger pressure, amount of ink, cooperation of the person being fin-
gerprinted, and skill of the person taking the finger images can all contribute
to the amount of finger image data recorded.
For each roll or electronic capture there should be enough minutiae and
ridge flow to match with another image. If the image is of poor quality, or if a
transmission error between the capture device and the database occurred,
the finger can be re-rolled to produce an image of acceptable quality. A good
finger image capture can result in as many as 100 or more individual minutiae
points.
Assume two agencies have similar tenprint records needing to be converted
into electronic images. The first agency feels that whatever card is identified as
the master tenprint record for the person (perhaps the first tenprint card,
perhaps the most recent) is the card that should be converted. The other
agency first reviews each tenprint record and then selects the best quality card
to be converted. This quality control step will provide a superior database, but
it is an expensive process since it involves personnel and considerable time.
AFIS software usually includes a feature that allows, either manually or auto-
matically, the replacement of a lower quality image with a better quality image.
Another feature offered by AFIS vendors is the creation of a virtual card made
of the best images from several tenprint records. The advances in AFIS tech-
nology have permitted the creation and maintenance of a database that con-
tains every image of every tenprint record, regardless of the number of tenprint
records a person has on file. For a subject who has been arrested eight times,
for example, all 80 images (ten fingers ¥ eight tenprint cards) can be searched.
To do so requires vast storage farms and extremely fast matchers, but it is an
option currently offered by AFIS vendors.

8.5.2.3 How Many Records Are Stored on the Latent
Cognizant Database?
The larger the database, the greater the opportunity to make a latent print iden-
tification. If the subject has never been enrolled, i.e., has never had prints taken
for this agency, there is no chance of making an identification. If the agency
has a large database, there is at least a chance of making the ident if the person
has been enrolled.