NCJ Number
217217
Journal
Journal of Forensic Sciences Volume: 52 Issue: 1 Dated: January 2007 Pages: 65-69
Date Published
January 2007
Length
5 pages
Annotation
A blind trial study that used an applied crime-scene methodology was used to evaluate a previous study in which mechanical engineering models were used to determine impact velocity and droplet volume for circular bloodstains by measuring stain diameter and counting "spines" that radiated from their outer edges.
Abstract
The findings of this study confirm that bloodstain measurements can be combined to predict both impact velocity and droplet volume. In addition, the consequences of this correlation are the basis for three general trends when comparing circular bloodstains on the same crime-scene surface before performing a calibration. First, when the larger bloodstain has fewer spines, it will have been caused by a larger droplet that impacts at a lower velocity. Second, when the larger bloodstain has greater spines, it will have been caused by a larger droplet that impacts at a higher velocity. Third, blood stains without spines or on different surfaces, cannot be compared in this manner. Further research will be required to confirm these trends and to evaluate whether they remain valid beyond this experimental range. Calculations from bloodstains produced on paper, drywall, and wood were used to develop surface-specific equations to predict 39 unknown mock crime-scene bloodstains created over a range of impact velocities (2.2-5.7 m/sec) and droplet volumes (12-45 ml). 2 tables, 6 figures, and 10 references