NONRANDOMNESS OF STRIATION EVIDENCE

• NCJ Number: 52856
• Journal: Journal of Police Science and Administration Volume: 6 Issue: 4 Dated: (DECEMBER 1978) Pages: 413-415
• Author(s): J I THORNTON
• Date Published: 1978
• Length: 3 pages
• Corporate Author: International Assoc of Chiefs of Police
• Publication Format: Article
• Language: English
• Country: United States of America
• Note: *This document is currently unavailable from NCJRS.

Annotation

MATHEMATICAL EVIDENCE IS PRESENTED TO SHOW THAT STRIATED IMPRESSIONS ENCOUNTERED IN TOOLMARK AND FIREARMS EVIDENCE ARE NOT RANDOM OCCURRENCES BUT RESULT FROM MANUFACTURING CONDITIONS WHICH CAN BE DETERMINED.

Abstract

A DETERMINISTIC M0DEL IS PRESENTED TO INVESTIGATE THE RANDOMNESS OR NONRANDOMNESS OF STRIATION EVIDENCE. A FORTRAN PROGRAM WAS WRITTEN TO SOLVE AN EQUATION YIELDING A TABLE OF PATTERNS AGAINST WHICH ACTUAL STRIAE COULD BE MEASURED. WHEN VARIOUS TOOLMARKS WERE COMPARED WITH THIS TABLE, THE INCIDENCE OF RANDOMNESS WAS 0.18. THE MANUFACTURING PROCESS WHICH PRODUCES STRIAE ON A SCREWDRIVER HEAD IS EXPLAINED. IT IS SUGGESTED THAT VIEWING STRIATIONS AS 'UNIQUE' PATTERNS AND NOT AS 'RANDOM' PATTERNS WILL GIVE EXAMINERS A MORE POSITIVE APPRECIATION OF THIS TYPE OF EVIDENCE. FOOTNOTES PROVIDE REFERENCES. THE FORTRAN PROGRAM IS AVAILABLE FROM THE AUTHOR. (GLR)