The influence of Close Non-Match fingerprints similar in delta regions of whorls on fingerprint identification.

Fingerprint identification errors may be due to the high similarity of fingerprints from different sources, especially when queries are conducted in a large database with the application of the Automatic Fingerprint Identification System (AFIS). In this study, a database of ten-prints of 6.964 million individuals was used; 20 sets of 60 simulated fingermarks of different qualities were used and compared with fingerprints from the database. A total of 245 queries were conducted based on both the quality of each fingermark and the number of minutiae. Four types of results were obtained from these queries on the large database, and were categorized as follows: (A) Neither Same Source nor Close Non-Match appears in the candidate list, (B) Only Same Source appears, (C) Only Close Non-Matches appear, and (D) Both Same Source and Close Non-Matches appear. When the quality of the fingermark was improved, more minutiae could be identified, and the degree of accuracy of the placement as well as orientation was higher. As a result, highly Close Non-Match fingerprints appeared; this made it harder to distinguish these fingerprints from Same Source fingerprints, especially in the large database. We concluded that more highly Close Non-Matches might appear when the database is consistently expanded, and an increasing number of Close Non-Matches might be found with a higher ranking and score than the Same Source; this would make the identification harder for examiners and might increase the possibility of identification errors.