NCJ Number
183890
Journal
Journal of Forensic Sciences Volume: 44 Issue: 6 Dated: November 1999 Pages: 1136-1150
Date Published
November 1999
Length
15 pages
Annotation
This article proposes several criteria for making decisions about comparing sets of debris that involve the transfer of non-component particles and fibers (those produced from something other than the item itself) using a model based upon rudimentary set theory.
Abstract
Decisions about the significance of an association or an exclusion based upon trace evidence require an evaluation of debris in its context; reference points for such evaluation are presented. Samples of debris from the sites relevant to the event under investigation must be available, as well as debris standards from the usual environments of the people involved. The samples must be of an amount and quality that permit a determination of normal versus foreign debris. The author proposes criteria for establishing contact based upon corresponding sets of particles and fibers, for excluding contact in the absence of corresponding particles or fibers, and for refraining from making either an association or an exclusion. Conditions for reaching qualified conclusions or other types of associations when these criteria are only partially met are also discussed; conclusions may sometimes be reached if potential sources for debris particles and fibers can be found. Decisions about the strength of an association or an exclusion based on comparisons of non-component debris particles and fibers can be made by reference to the criteria for reaching a conclusion. The criteria can be tested via Bayes' Theorem. The analysis itself is based primarily on light microscopy, although other methods may be used as well. Ten case examples are presented. 85 references