Estimation of postmortem interval (PMI) as revealed through the analysis of annual growth in woody tissue.

The discovery of human remains lying across a black spruce (Picea mariana) leader (branch) that subsequently grew up around the remains provided an opportunity to use the growth ring pattern to estimate the postmortem interval (PMI). As these remains were discovered in an advanced state of decomposition in October of 2000, and it was clear that relevant insect evidence was not forthcoming, this novel approach to estimating PMI was proposed. The asymmetrical growth of the leader resulted in a correspondingly asymmetrical pattern of its growth riings. As the date of cutting the leader was known, it was possible to evaluate the asymmetrical growth pattern to provide an estimation of PMI. Fine polishing of the cross section and computerized quantification of ring widths enabled an estimation of the displacement of the leader, and hence the time the decedent's body was so positioned. By charting the ring-width differential for the leader, it was concluded that the displacement occurred sometime between July of 1993 and May of 1994. The actual date of disappearance was confirmed to be August 24, 1993.