Forensics • Profiling • Victimology • Interrogations
Blood spatter at the scene of a crime can be
useful in reconstructing what and how events took place by determining the
location of the source of the blood source or the direction of movement.
Blood spatter can also help determine whether a person was at the crime
scene during the offense. There is a very basic classification system
of spatter patterns, which is based upon the velocity of the object causing
the impact upon the blood source and the size of the resulting blood pattern
or spatter evidence.
Low Velocity - This type of spatter is
usually caused by an impact to the blood source at a rate of 5 feet per
second and is usually about 4 millimeters in diameter.
Medium Velocity - This type of spatter is
usually caused by an impact to the blood source at a rate of 5-25 feet per
second. Stains caused by this type of force are usually 1-3
millimeters in diameter, but may be larger or smaller.
High Velocity - This type of spatter is
usually caused by an impact to the blood source in excess of 100 feet per
second and is usually less than 1 millimeter in diameter, although it can be
larger or smaller.
When blood hits a surface at an angle other than 90 degrees,
the direction of it's path will be able to be viewed, interpreted and
measured, which allows investigators to reconstruct what and how something
occurred.
Although the picture to the left is is computer generated and
not very realistic in appearance, it was made to look the way it is to
exemplify how the direction of the path of blood can be indicated by "tail"
of the stain. In this example, the blood traveled from the lower left
to upper right. If an investigator was attempting to determine where
the source of the blood was when the stain was made, an equation can be
used, which will give an accurate location.
