ESTABLISHING THE EVIDENTIAL VALUE OF A SMALL QUANTITY OF MATERIAL FOUND AT A CRIME SCENE

Treatments of the interpretation of trace evidence found at a crime scene normally start with the assumptions that the evidence is relevant, in the sense that it must have been left by the offender, and that there is no possibility that the evidence could have come from the suspect by purely innocent means. As the sensitivity of forensic techniques increases, there will be a tendency to use them in cases where one or both of these two assumptions are dubious. This paper shows how the theory of transfer evidence can be used to understand the interpretation of such cases.