''Forensics'' Blood Stain Patterns

 In 1955, the first meaningful achievement of bloodstain evidence was credited to Dr. Paul Kirk of the University of California at Berkeley (Nordby).

First of all, blood contains a fluid portion we call plasma. Plasma contains natural segments of erythrocytes, leukocytes, and platelets. The nuclei of the leukocyte (white blood cells) are our source to DNA evidence. Furthermore, blood is similar to common fluids however, blood is held together by powerful cohesive molecular forces that generate a surface tension within each drop and on an external surface (Nordby).

Moreover, surface tension is a great way to determine the characteristics of bloodstain patterns. For instance, if a single drop of blood fell vertically on a nonporous surface there would be little to no spatter. In contrast, if the blood fell vertically on a porous or rough surface nine times out of ten there will be a significant amount of spatter. The geometry of determining an individual bloodstain pattern can be very complex. The direction of travel, area of origin and angle of impact are important factors in reference to determining the area of convergence to blood stain patterns (Nordby).

Not to mention, bloodstain spatters vary in size.  After identifying bloodstain spatters; gathering medical, scene, and case related evidence; determining the mechanism category becomes easier for the analyst to establish specifics.  Categories of blood spatters are based on the mechanisms. Such as:

Secondary mechanisms                 Impact mechanisms            Projection mechanisms

Satellite Spatter                                   *Gunshot                                *Cast off

*Beating/Stabbing                  *Arterial

*Power tools/etc.                    *Expirated

Furthermore, arterial punctures can produce very large quantities of blood. When an artery is punctured it is usually obvious. This is because; arterial punctures varying from large gushing or spraying patterns to small spray patterns are obvious. Like, if an individual was stabbed in the neck and an artery was punctured this type of injury would result in a large amount of spraying or gushing from the body; developing obvious patterns of an arterial spurt (Nordby).

Lastly, transfer bloodstain patterns are when an object wet comes in contact or whipping with an unstained object or secondary surface. Transfer patterns can be a very useful part of solving an investigation. If a suspect dropped a knife used in a murder in the woods and it was recovered and if trace evidence were found, the evidence can be examined to rule out the suspect involved (Nordby).