Characteristics of the Distance and Space Required for Knife Slashing Using a Motion Capture System

Abstract

Objectives: To investigate the relationship between the perpetrator's sex, victim's position and slashing location as well as anthropometric parameters on distance and space required for slashing, to provide the theoretical basis for the judgment of whether the crime scene was consistent with the criminal activity space.

Methods: The kinematics data of 12 male and 12 female subjects slashing the neck of standing and supine mannequins as well as the chest of the standing mannequins with a kitchen knife were obtained by using a 3D motion capture system. The relationship between the perpetrator's sex-victim's position, the perpetrator's sex-slashing location, and anthropometric parameters and the distance and space required for the slashing were analyzed by two-factor repeated measures ANOVA and Pearson correlation analysis respectively.

Results: Compared with slashing the neck of supine mannequins, the distance (L) and normalized L (l) of slashing the neck of standing mannequins were greater, while vertical distance (L_VR) and normalized L_VR (l_VR) of the knife side were smaller. Compared with slashing the neck of standing mannequins, the L and l slashing the chest of standing mannequins were greater, while L_VR and l_VR were smaller. Horizontal distance (L_HR) and normalized L_HR (l_HR) of the knife side in males were greater than that in females. Height and arm length were positively correlated with L, L_HR, and L_VR when striking the standing mannequins.

Conclusions: When slashing the neck of supine or standing victims, the slashing distance is shorter and the slashing height is greater. Furthermore, the distance and space required for slashing are correlate with anthropometric parameters.

Keywords: body position; forensic medicine; mannequin; motion capture; slashing; slashing distance; space required for slashing.