Crime Scene Forensics, LLC
Bloodstain Pattern Analysis

1. Distance from the blood source to the target
2. Direction of travel and impact angles
3. Nature of the force used to cause the bloodshed
4. The object used to cause the bloodshed
5. Sequencing of multiple bloodshed events
6.Interpretation of contact or transfer patterns

When properly documented, bloodstain patterns found at the crime scene, or on a
particular person's clothing, can be used to:
1. Confirm or refute the position of a victim, witness, suspect, or defendant
2. Determine if there is evidence of a struggle, or if the assault is "one
3. Confirm or refute statements made by principles in the case:
     IE: Are stain patterns on a particular person's clothing consistent
          with accounts given by the victim, witness, or defendant?

  • Spatters = Force

  • In order for spatters to be produced, an external force must be applied to a
source of liquid blood

  • The force must be great enough to overcome the surface tension of the blood

  • Blood will not break up unless it is acted upon by force.

  • As a general rule; the greater the amount of force applied to the source of
liquid blood, the smaller the resulting blood spatters

  • As a general rule, spatters on a suspects clothing or person, may indicate that
he was in direct proximity, to the blood source, at the time the force was
being applied

The simplest type of blood spatter analysis is
determining spatters from transfers.

Spatters are produced when a source of liquid
blood is acted upon by an external force. The
blood droplets, created by the force, travel
through the air before landing on a target

Transfers occur when a blood source comes
in direct contact with a target surface area.
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  • The type of surface that free falling blood (drip stain) strikes, affects the appearance
   of the resulting stain.

  • Drip stains on a smooth surface will make a more uniform, circular shape with smooth edges.

  • Drip stains on a course surface will make an irregular shaped stain with rough or
  jagged edges.

  • Blood drop that falls at the speed/force of normal gravity

  • These drops usually fall from an open wound, or from
a surface that is saturated with blood

  • Blood forms a spherical shape (perfect circular shape)
immediately upon separating from the blood source.

  • The spherical shape is caused by the surface tension of the blood.

  • Surface Tension causes the blood drop to pull itself in; both horizontally and
vertically, forming what is sometimes referred to as an invisible skin

  • The blood drop will settle into a spherical shape, as a result of the surface  

  • The surface tension will maintain the sphere shape of the blood drop until it  
impacts with the surface.
Angle of Impact:  
The steeper the impact, the more elliptical or elongated, the
blood drop

The "tail" points to the direction of the blood drop

       When a bullet strikes a target, some
high force impact spatter
may be directed
back toward the gun that fired the shot.
This is known as
back spatter

       If the bullet exits its target, a larger
amount of high force impact spatter may be
directed in the same direction as the bullet.
This is known as
forward spatter
Bloodstain Pattern Analysis: is the examination of the shapes, locations, and distribution of patterns of bloodstains, in
order to provide an interpretation of the physical events that gave rise to their origin. The analysis may be performed on
scene, in a laboratory setting, or in an office by reviewing case materials, such as photographs and reports. Bloodstain
Pattern Analysis is a general or class characteristic science and opinions are often expressed in more general terms. For
example, the analyst may be able to identify particular bloodstains or bloodstain patterns at a scene, and then offer one or
more possible mechanisms by which those stains or patterns were created. The opinions may then be applied to the overall
case investigation or scene reconstruction.

 Crime Scene Forensics, LLC offers complete review of cases involving bloodstains. It is important to understand that
Bloodstain Pattern Analysis is one component of a crime scene investigation. The analysis of the bloodstains need to
considered in the context of the scene and its associated evidence. We will incorporate all the case facts and render opinions
based on case facts and scientific principles.
Below are some quick facts and information regarding bloodstain pattern analysis. For further information, or to
request a CV or fee schedule, please
contact us
    The amount of high force impact spatter created will depend upon the size or caliber of the bullet fired, as well as the
distance from the muzzle of the gun to the target. The larger the bullet, the greater the potential for more significant spatter.
The closer to the target that the gun is fired...the greater the potential for more significant spatter.
     For a complete list of bloodstain pattern terms, as recommended by the Internation Association of Blood Stain
Pattern Analysts. (IABPA), go to: These terms should serve as a guide, for those who work and
teach in the field of Blood Stain Pattern Analysis. These terms are not meant to be all encompassing