Forensic Analysis of Stab Wounds

     Estimating the length of a knife from the depth of the wound it makes can be tricky, because different parts of the body have different degrees of elasticity or give. Abdominal tissue, for instance, is soft, so that a three-inch knife plunged into the gut can be driven all the way back to the spine, producing a six-inch-deep stab wound.

     At most autopsies, a trained forensic eye will take tissue flexibility into consideration and compensate appropriately in estimating puncture depth. On occasion, however, medical examiners forget to take account of this variable and as a result overestimate the length of the killing instrument, sometimes by several inches…

     Stab wounds delivered to the chest do not usually cause such miscalculations. Owing to the hardness of the ribs and the sternum, this area tends not to cave in when struck, even by the point of a dagger. In some cases, it is true, a rib cage will collapse under the pressure of a powerful jabbing thrust. I see this most often on the soft bones of children and the brittle bones of the elderly. But in a robust, healthy adult, the durable plating of the rib cage and sternum acts as a suit of armor, cracking and scarring but usually not breaking against the force of the lance.

Frederick Zugibe, M.D., Ph.D. and David L. Carroll, Dissecting Death, 2006