When blood drips vertically onto a flat surface the blood stain is circular. When blood impacts a flat surface at an angle, then an elliptical stain is formed. The angle of impact can be estimated based on measurements of the blood stain.



(1) width of the blood stain in mm

(2) length of the blood stain in mm


SIN(impact angle in degrees) =

= (width of the stain) / (length of the stain)


impact angle in degrees =

= ARCSIN(width of the stain) / (length of the stain)


If multiple stains were made at the same time, then a distribution for the angle estimates can be used to get a better estimate for the true angle of impact.



• The measurements must be taken very carefully. It is important not to include any artifacts or distortions.


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