NCJ Number
194648
Journal
Canadian Society of Forensic Science Journa; Volume: 34 Issue: 4 Dated: December 2001 Pages: 173-189
Date Published
December 2001
Length
17 pages
Annotation
This article describes the Directional Analysis theory of bloodstain patterns making use of virtual strings drawn by a computer and presents the results of an experiment that created a bloodstain pattern and used directional analysis to locate the blood source with good accuracy.
Abstract
Based on the string method, Directional Analysis of bloodstain patterns is a mathematical procedure developed to find the directions in space (virtual strings) pointing from the bloodstains to a location directly above the location of the blood source. It makes use of virtual strings that are drawn by a computer. The Directional Analysis theory depends on the physical laws of motion and the resolution of a velocity into its three components and simple trigonometry. However, it does not depend on unknown quantities, such as droplet sizes and speeds. The analysis is carried out with the aid of a computer and digital cameras gather the evidence. A laboratory experiment was conducted to validate Directional Analysis in both theory and practice. Six bloodstains were chosen for fast upward movement of the corresponding blood droplets. Results indicated a strong agreement between the measured position of the blood source and the true position. This validated the theory of virtual strings and the method of ellipses developed in measuring the impact of angles of the blood droplets. Figures