Tool Mark Striations in Pig Skin Produced by Stabs From a Serrated Blade

Stab wounds produced by serrated blades are generally indistinguishable from stab wounds produced by nonserrated blades, except when visible tool mark striations are left on severed cartilage. Using a pig-skin experimental model, we explored the possibility that similar striations may be left in skin. Stabs into pig skin were made using a straight spine coarsely serrated blade (121), a drop point finely serrated blade (20), a clip point irregular coarsely serrated blade (20), a drop point coarsely serrated blade (15), and as controls 2 nonserrated blades (40). Tool mark striations could be seen on the skin wall of the stab canal in all stabs made using serrated blades but in none with nonserrated blades. The striation pattern, reflecting the class characteristics of the serrated blade, was the same as that described in cartilage but less well defined. Fixation of the specimen with Carnoy's solution best preserved visible striations, and fixation with formaldehyde after staining with 5% Neutral Red was also satisfactory. Casting with vinyl polysiloxane dental impression material greatly facilitated photo-documentation. Applying the technique to homicidal stabbings may help identify stab wounds produced with serrated blades.