Page 14 - Patterns of Murder Blood Spatter
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While the overhead viewing technique is generally first to recognize a relationship between the length
the easiest way to determine the convergence/ and width of a resulting stain and the angle of the
origin, this technique is limited to determining projected droplet’s impact. This relationship was
a two dimensional convergence point and no further refined by Dr. Herb MacDonell, who applied
information on height is available to form a true mathematical sine functions to the relationship.
point of origin in three dimensional space. In each Because droplets in flight are spherical, when the
instance in which a stain’s path can be defined, a droplet impacts the target, its dimensions can be
line is drawn in the opposite direction. By mapping used to define the angle of impact. The inverse
the path of multiple droplets, an intersection of this sine relationship provides an estimate
point can be determined. The intersection point of impact angle accurate to within 5°-7°. These
of droplets caused by the same impact should be techniques require the ability to define a well
close to the origin of the blow. Additionally, multiple formed stain, where length and width of the stain
blows can be established by determining clusters can be clearly and precisely measured. Satellite
of intersection points from multiple droplets. spatter and spines must also be excluded, so only
the elliptical part of the stain is measured.
To establish a specific location above the point
of convergence, an investigator must use a side- Building on these theoretical bases for determining
view approach, requiring the determination of a points of origin, two three-dimensional techniques
droplet’s impact angle. Dr. Victor Balthazard was have been developed to aid analysts in evaluating
14 THE MYSTERY OF LYLE AND LOUISE
