NCJ Number
2826
Date Published
1971
Length
39 pages
Annotation
RESULTS OF PILOT PROJECT TO INVESTIGATE TIME DEPENDENT NATURE OF EPR SIGNAL OF GUNPOWDER AND PRIMER RESIDUES.
Abstract
THE PYROLYSIS OF PRIMER COMPOUNDS AND GUN POWDERS WHICH OCCURS UPON THE DISCHARGE OF A CARTRIDGE IMPARTS TO THESE MATERIALS AN ELECTRON PARAMAGNETIC RESONANCE (EPR) SIGNAL INDICATIVE OF THE PRESENCE OF FREE RADICALS. THESE PYROLYTICALLY INDUCED FREE RADICALS ARE OBSERVED TO DISAPPEAR WITH TIME, AS SEEN IN SERIAL EPR SPECTRA OBTAINED FROM EACH RESIDUE OVER A PERIOD OF TIME. THE PURPOSE OF THIS FEASIBILITY STUDY WAS TO DETERMINE IF THE TIME DEPENDENT EPR SIGNALS COULD BE CHARACTERIZED TO AN EXTENT THAT WOULD PERMIT THEIR UTILIZATION BY CRIMINALISTICS EXPERTS. SUCH INFORMATION MIGHT ALLOW ONE TO DETERMINE IF A PRIMER COMPOUND HAD BEEN DISCHARGED RECENTLY, ESTIMATE THE ELAPSED TIME FROM DISCHARGE OF THE PRIMER COMPOUND, AND ESTABLISH THE MANUFACTURER OF THE PRIMER COMPOUND. RESIDUES FROM A TOTAL OF 53 PRIMERS WERE OBTAINED FROM THE DISCHARGE OF FIVE DIFFERENT BRANDS OF AMMUNITION. FROM THESE SAMPLES, APPROXIMATELY 325 EPR SPECTRA WERE OBTAINED AND ANALYZED. THE FINDINGS INDICATED THAT THERE WERE EASILY DISCERNIBLE DIFFERENCES BETWEEN BRANDS OF PRIMERS BASED ON THEIR EPR SIGNAL AND THE TIME-COURSE DECAY OF THESE SIGNALS. THE AUTHORS STATE THAT DATA WERE, WITHIN LIMITS, REPRODUCIBLE AND PREDICTABLE. IT WAS CONCLUDED THAT EPR SPECTROMETRY SHOWS PROMISE AS A TOOL FOR FORENSIC CRIMINALISTICS. (SNI ABSTRACT)