NCJ Number
191260
Journal
Journal of Forensic Identification Volume: 51 Issue: 4 Dated: July/August 2001 Pages: 367-377
Date Published
2001
Length
11 pages
Annotation
This article explains how a microscopic examination of plant fragments in fecal samples can be used to link a suspect to a crime scene.
Abstract
Humans usually consume three major meals each day and a variable number of snacks that may contain plant materials; however, defecation occurs on the average every 1.1 days, resulting in a mixture of meals appearing in any given fecal sample; therefore, a fecal sample may be a composite of a number of unique meals that give it even greater individualization than if it were based on a single meal. Furthermore, some materials from a single meal may occur in more than one stool sample. Two types of information may be obtained from a fecal sample for drawing conclusions. The first is the identification of similar plant cells in both samples being examined. The second useful piece of information is the relative frequency of each plant type in the fecal sample. Together, these data indicate that not only were the same materials present, but they were present in the same relative proportions. It is not uncommon to find some overlap in certain common plant types in unrelated samples; but in the authors' experience, the frequency has always been different. Thus, two samples that have many of the same plant cell types in the same proportions strongly suggest they are from the same original sample. The results of a fecal analysis can be used in several ways. In one case, the authors connected stains on a male suspect's clothing with a fecal sample from a female rape-homicide victim as well as with fecal stains on her clothing. In another case, the authors matched fecal material in the suspect's clothing with a sample left at a burglary site. This article explains the procedures used, including the preservation of samples, the processing of fecal material in the laboratory, the preparation of microscope slides, and the identification of plant cells and plant fragments. 4 figures and 5 references