NCJ Number
57970
Date Published
1978
Length
19 pages
Annotation
THE INDIVIDUALITY OF FINGERPRINTS AND THE OCCURRENCE OF FINGERPRINT CHARACTERISTICS IS MATHEMATICALLY MODELED AS A TWO-DIMENSIONAL MULTIVARIATE POISSON PROCESS.
Abstract
FINGERPRINT CHARACTERISTIC IDENTIFICATION IS BASED ON RIDGE LINE DETAILS. THESE DETAILS ARE CALLED GALTON CHARACTERISTICS AND ARE OF 10 TYPES (ISLANDS, BRIDGES, SPURS, DOTS, RIDGE ENDINGS, FORKS OR BIFURCATIONS, LAKES, TRIFURCATIONS, DOUBLE BIFURCATIONS, AND DELTAS). FORMULA DEVELOPMENT IS DESIRABLE TO EVALUATE THE PROBABILITY OF PARTIAL FINGERPRINTS, SUCH AS CRIME SCENE FINGERPRINTS. THE TWO-DIMENSIONAL MULTIVARIATE POISSON MODEL TAKES INTO ACCOUNT THE DEPENDENCE BETWEEN CELLS CONSIDERED IN FINGERPRINTS AND PROVIDES ALTERNATIVES FOR THE TREATMENT OF MULTIPLE OCCURRENCES OF CHARACTERISTICS. IT IS ASSUMED THAT THE OUTCOME FOR A PARTICULAR CELL DEPENDS ON OUTCOMES IN OTHER CELLS ONLY THROUGH OUTCOMES IN ADJACENT CELLS. IT IS ALSO POSTULATED THAT THE EXPECTED NUMBER OF OCCURRENCES OF FINGERPRINT CHARACTERISTICS IN A CELL DEPENDS ON THE NUMBER OF NEIGHBORING CELLS THAT ARE OCCUPIED. THE NUMBER OF OCCURRENCES IN A CELL IN A POISSON RANDOM VARIABLE, AND THE NUMBER OF OCCURRENCES IN A CELL IS DISTRIBUTED ACCORDING TO A POISSON PROCESS. CELLS AT THE BORDER OF A FINGERPRINT ARE NOT TOUCHED BY THE FULL COMPLEMENT OF ADJACENT CELLS AND REQUIRE SPECIAL TREATMENT. EXAMPLES OF THE MODEL'S APPLICATION ARE DETAILED. SUPPORTING DATA AND EQUATIONS AND A BIBLIOGRAPHY ARE INCLUDED. (DEP)