The Directional Analysis of Bloodstain Patterns Theory and Experimental Validation

Abstract

Directional Analysis of bloodstain patterns is a mathematical procedure developed by the author that is based on the string method. It finds the directions in space (virtual strings) that point from the bloodstains to a spot directly above the location of the blood source. When viewed from above, the virtual strings are seen to converge onto the source position. When viewed from the side, the virtual strings provide an upper limit for the probable height of the blood source.The theory relies only on the well-known physical laws of motion, the resolution of a velocity into its three components and simple trigonometry, and does not depend on unknown quantities such as droplet sizes and droplet speeds. This procedure has a solid basis in physics and mathematics, and satisfies the criterion of sound scientific methodology for bloodstain evidence specified by the courts. Digital cameras are used for gathering the evidence and the analysis is carried out with a computer.The second part of this paper will describe a laboratory experiment that validates “Directional Analysis” both in theory and in practice.