NCJ Number
1907
Date Published
1970
Length
109 pages
Annotation
SAMPLING, ACTIVATION ANALYSIS WORK, RESULTS, AND STATISTICAL INTERPRETATION OF PAINTS, BULLET LEAD, AND GUNSHOT RESIDUES ARE DESCRIBED.
Abstract
PAINT CAN BE HIGHLY CHARACTERIZED BY NEUTRON ACTIVATION ANALYSIS (NAA). A GIVEN BATCH OF PAINT IS HIGHLY UNIFORM, BUT THERE ARE SIGNIFICANT BATCH-TO-BATCH DIFFERENCES IN THE COMPLETE ARRAY OF OBSERVED ELEMENTAL CONCENTRATIONS (FINGERPRINTS), AND DIFFERENT PAINTS HAVE HIGHLY DIFFERENT FINGERPRINTS. ON THE AVERAGE, THE CHANCE THAT TWO DIFFERENT PAINTS WILL BE ACCIDENTALLY MATCHED BY NAA IS CONSIDERABLY LESS THAN ONE IN A BILLION. A REVIEW OF EARLIER NAA DATA REGARDING PAPER SAMPLES SHOWS THAT NEARLY THE SAME DEGREE OF CHARACTERIZATION SHOULD BE POSSIBLE BY NAA WITH THIS MATERIAL AS HAS BEEN ACHIEVED WITH PAINT. BULLET LEAD ANALYSIS BY INSTRUMENTAL NAA HAS BEEN SHOWN TO BE USEFUL, ALTHOUGH TO A CONSIDERABLY LESSER DEGREE THAN IN THE CASE OF PAINT, PAPER, OR GUNSHOT RESIDUES. RECOMMENDATIONS TO INCREASE THE USEFULNESS OF BULLET LEAD COMPARISONS BY NAA ARE GIVEN. THE PROBABILITIES ASSOCIATED WITH ALTERNATIVE INTERPRETATIONS OF THE NAA DETERMINATION OF GUNSHOT RESIDUE ELEMENTS IN A GIVEN CASE ARE DEFINED FOR EACH COMBINATION OF A NUMBER OF SPECIFIED OCCUPATIONAL CATEGORIES AND WEAPON CALIBERS. THE DISCUSSION OF EACH OF THE FOREGOING SUBJECTS INCLUDES A DESCRIPTION OF RELATED WORK DURING PREVIOUS REPORT PERIODS. (AUTHOR ABSTRACT MODIFIED.)