Investigating the Force Relative to Blood Stain Size and Pattern

“Every contact leaves a trace”- Dr. Edmond Locard (1877–1966), all trace evidences represents a characteristic feature in reconstructing the crime scene. Mostly in crime scenes bloodstains can be found these stains can occur when blood falls passively due to force being applied to a body and these tiny droplets are helpful in reconstructing the crime scene. The aim of this research is to investigate the force relative to the bloodstain size and spatter pattern using a force sensor and propose new parameter in categorizing the type of spatter. In order to achieve these aims a set of preliminary experiments, gravity drop and impact spatter were conducted. In gravity drop, the width of the stains under different heights was studied and in impact spatter experiment, a known mass was dropped from different heights and spatter patterns were interpreted. Further sets of experiments were performed with the help of force sensor, which could give value of force in Newton (N). There were variety of weapons used for this project, namely wooden hammer, metal hammer and metal rod. In conclusion of this research, three different ranges of force Mild/Moderate/Severe were defined by interpreting the spatter pattern and stain size for single and multiple blows. Thus, investigating the force of impact based on the stain size, angle of impact and spatter pattern is not conclusive for the judgments. However, we can categorize the type of attack either mild/moderate/severe based on the stain size and spatter pattern that can be helpful in supportive of an argument during trial.