An Experimental Model of Tool Mark Striations by a Serrated Blade in Human Soft Tissues

Abstract

Tool mark analysis is a method of matching a weapon with the injury it caused. In a homicidal stabbing using a serrated knife, a stab wound that involves a cartilage may leave striations from the serration points on the blade edge. Assessing tissue striations is a means of identifying the weapon as having a serrated blade. This prospective study examines the possibility that similar striations may be produced in human soft tissues. Using tissues taken at the time of hospital-consented autopsies, stab wound tracks were assessed in a variety of human tissues (aorta, skin, liver, kidney, and cardiac and skeletal muscle). Stab wounds were produced postmortem with similar serrated and smooth-edged blades. The walls of the stab wounds were exposed, documented by photography and cast with dental impression material. Striations were identified by naked-eye examination in the skin and aorta. Photodocumentation of fresh tissue was best achieved in the aorta. Striations were not identified in wound tracks produced by the smooth-edged blade. Three blinded forensic pathologists were assessed for their ability to detect striations in photographs of wound tracks and had substantial interobserver agreement (κ = 0.76) identifying striations. This study demonstrates that tool mark striations can be present in some noncartilaginous human tissues.