NCJ Number
206535
Journal
Journal of Forensic Sciences Volume: 49 Issue: 4 Dated: July 2004 Pages: 781-783
Date Published
July 2004
Length
3 pages
Annotation
This paper reports on a case in which tree growth rings were analyzed to estimate the time of death (postmortem interval) in the case of a person who fell on a young black spruce at death, producing an intervention in the tree's normal growth; the time period from the start of this intervention could be determined from an analysis of the distinctive tree rings produced after the falling body disrupted the tree's normal vertical growth.
Abstract
The growth pattern of an individual tree ring depends not only on the environmental conditions at a given time but also on mechanical stresses on the tree, such as slope, snow creep, or partial wind-throw. Each of these factors can displace the tree's stem from its vertical growth direction. The response of a tree to such a vertical displacement is to develop "reaction wood" that produces a ring that is not uniform around the stem. The resulting rings become elliptical due to the greater growth on one side of the stem owing to an increase in localized cambial activity. In the case at issue, the body fell on the leader (terminal shoot) of a young black spruce that subsequently grew up around the body in an attempt to regain its normal vertical growth. This paper describes how the analysis of the tree's growth rings was the key to estimating the postmortem interval (PMI). Since the remains were discovered in an advanced state of decomposition in October 2000, and it was clear that relevant insect evidence was not available, the time-relevant growth patterns of the tree leader were analyzed to determine the PMI. Because the date of cutting the tree's leader was known, it was possible to assess the asymmetrical growth pattern to provide an estimation of the PMI. The fine polishing of the leader's cross section and the computerized quantification of ring widths produced an estimation of when the leader was displaced, and hence the time when the decedent's body intervened to displace the leader from its vertical positioning. By charting the ring-width differential for the leader, analysts concluded that the displacement occurred between July 1993 and May 1994. The actual date of the deceased person's disappearance was reported by witnesses to be August 24, 1993. 3 figures and 7 references