EQUIPMENT SYSTEMS IMPROVEMENT PROGRAM - FINAL REPORT ON PARTICLE ANALYSIS FOR GUNSHOT RESIDUE DETECTION

• NCJ Number: 43632
• Author(s): G M WOLTEN; R S NESBITT; A R CALOWAY; G L LOPER; P F JONES
• Date Published: 1977
• Length: 217 pages
• Contract Number(s): J-LEAA-025-73
• Sponsoring Agency: US Dept of Justice; US Dept of Justice NIJ Pub
• Corporate Author: Aerospace Corporation
• Sale Source: National Institute of Justice/
• Language: English
• Country: United States of America

Annotation

PARTICLE ANALYSIS, USING A SCANNING ELECTRON MICROSCOPE EQUIPPED WITH X-RAY ANALYSIS, MAKES DETECTION OF GUNSHOT RESIDUE POSSIBLE FOR UP TO 12 HOURS AFTER A FIRING. PARTICLE PATTERNS ARE ILLUSTRATED, TECHNIQUE DESCRIBED.

Abstract

THIS REPORT ON THE DEVELOPMENT OF THE PARTICLE ANALYSIS METHOD OF GUNSHOT RESIDUE DETECTION IS PRESENTED IN MANAUAL FORM TO PROVIDE INFORMATION NECESSARY TO PERFORM SUCCESSFUL ANALYSES, INTERPRET RESULTS, AND EXPLAIN AND DEFEND THESE FINDINGS IN COURT. PARTICLE ANALYSIS IDENTIFIES GUNSHOT RESIDUE WITH GREATER CERTAINTY THAN PREVIOUS METHODS BECAUSE DISCRIMINATION OF RESIDUE FROM A MAJORITY OF OCCUPATIONALLY CAUSED DEPOSITS OF LEAD, BARIUM, OR ANTIMONY IS POSSIBLE. PARTICLES ARE LIFTED FROM THE HAND WITH AN ADHESIVE-COATED DISK; PRESENT ADHESIVES PROVIDE 70-75 PERCENT COLLECTION EFFICIENCY. THE DISK IS INSERTED DIRECTLY INTO THE SCANNING ELECTRON MICROSCOPE. RESEARCH FOUND THAT EXAMINATION OF 10-15 PERCENT OF THE SAMPLE AREA IS SUFFICIENT TO ALLOW VALID EXTRAPOLATIONS AS TO NUMBER OF PARTICLES, SIZE, AND COMPOSITIONAL DISTRIBUTION IN THE ENTIRE SAMPLE. PARTICLE DISTRIBUTION PATTERNS HAVE BEEN FULLY DETERMINED FOR 24 COMMON CARTRIDGES AND PARTIALLY DETERMINED FOR A NUMBER OF ADDITIONAL SIZES. ACTUAL FIELD WORK COLLECTED GUNSHOT RESIDUE IN 90 PERCENT OF CASES IN WHICH A HANDGUN HAD BEEN USED. DELAY BETWEEN FIRING AND SAMPLE COLLECTING WAS 1 TO 13 HOURS WITH AN AVERAGE OF 3-1/4 HOURS. A 10 PERCENT LOSS OCCURRED DURING THE FIRST HOUR AFTER SHOOTING; THE LOSS WAS A FACTOR OF 100 AFTER 10 HOURS. LONG GUNS WERE USED IN ONLY 15 OF THE FIELD CASES. RESIDUE WAS FOUND IN 50 PERCENT WITH RIFLES ACCOUNTING FOR A MAJORITY OF THE NEGATIVE RESULTS AND SHOTGUNS A MAJORITY OF THE POSITIVE RESULTS. IN SUICIDES, GUNSHOT RESIDUE WAS DETECTED AS MUCH AS 5 DAYS AFTER FIRING WHEN THE BODY WAS UNDISTURBED. TABLES AND PHOTOGRAPHS PRESENT RESIDUE CHARACTERISTICS AND CLASSIFICATION OF PARTICLES, CHARACTERISTICS OF PARTICLES BY CARTRIDGE, PROCEDURE OF X-RAY ANALYSIS, OPERATING COSTS, AND SAMPLE CASE REPORTS. IT WAS FOUND THAT AN EXPERIENCED OPERATOR COULD COMPLETE EXAMINATIONS FOR TWO AVERAGE CASES IN AN 8-HOUR DAY. FOR LARGE LABORATORIES, AUTOMATION OF THE PROCEDURE IS POSSIBLE.