SIFTER (SYSTEM FOR THE IDENTIFICATION OF FINGERPRINTS BY TECHNICAL SEARCH OF ENCODED RECORDS) - AN EXPERIMENTAL COMPUTERIZED FINGERPRINT TECHNICAL SEARCH SYSTEM FOR STATE IDENTIFICATION BUREAUS

• NCJ Number: 16290
• Author(s): G L CAMPBELL
• Date Published: 1974
• Length: 132 pages
• Grant Number(s): 73-SS-99-3301
• Sponsoring Agency: US Dept of Justice
• Corporate Author: SEARCH Group Inc.
• Sale Source: National Institute of Justice/
• Publication Type: Program/Project Description
• Language: English
• Country: United States of America

Annotation

COMPUTERIZED METHOD OF SEARCHING A LIBRARY FILE FOR A GIVEN INQUIRY FINGERPRINT.

Abstract

THE SIFTER FINGERPRINT TECHNICAL SEARCH SYSTEM IS DESIGNED TO DERIVE THE MAXIMUM SEARCHING EFFECTIVENESS FROM THE INFORMATION CONTAINED IN A FINGERPRINT CLASSIFICATION. SIFTER USES THE NCIC CLASSIFICATION SYSTEM WHICH REQUIRES MANUAL ENCODING OF FINGERPRINT PATTERNS BY SKILLED TECHNICIANS. HOWEVER, THE BASIC APPROACH IS GENERAL AND CAN BE ADAPTED TO ANY CLASSIFICATION SYSTEM INCLUDING THOSE INVOLVING AUTOMATIC ENCODING. SIFTER WORKS BY COMPARING EACH INQUIRY CODE WITH EACH FILE ENTRY TO DERIVE A SCORE WHICH IS PROPORTIONAL TO THE PROBABILITY THAT THE TWO CLASSIFICATIONS REPRESENT THE SAME PERSON. A THRESHOLD IS SET SO THAT FILE ENTRIES WITH MATCHING SCORES ABOVE THE THRESHOLD ARE ACCEPTED AS POSSIBLE MATCHES (CANDIDATES) AND THOSE BELOW THE THRESHOLD ARE REJECTED. PROBABILITY TABLES FOR USE IN SIFTER ARE CONSTRUCTED FROM PAIRS OF CLASSIFICATIONS TAKEN AT DIFFERENT TIMES BUT KNOWN TO BE FROM THE SAME PERSON. OTHER TABLES ARE MADE FROM THE OBSERVED DISTRIBUTIONS OF PATTERN TYPES FOUND IN A LARGE FINGERPRINT FILE. IN USING THESE DATA, THE SYSTEM ADAPTS IN AN OPTIMAL WAY TO THE CHARACTERTERISTICS OF THE NCIC CLASSIFICATION SYSTEM. SOFTWARE PROGRAMS ARE DESCRIBED, AND SAMPLE PRINTOUTS ARE APPENDED. (AUTHOR ABSTRACT)