In sharp force fatalities, the congruence of the stabbing tool and the stab wound on the body surface can usually be assessed at least approximately by comparing corresponding post-mortem photographs with a potential murder weapon. The photographs must then of course meet the requirements of forensic documentation. Corresponding statements are also possible radiologically [1–2]. However, an exact match can usually not be determined without any doubt. The excision of stab wounds to compare stab injury and stab tool is unusual and would be pointless in elastic tissue such as skin. If there are no individual characteristics on the piercing tool or corresponding features on the stab wound, an absolute match with a reliable association between the puncture tool and the puncture itself cannot generally be postulated.

In the case reported here, however, it was possible to unequivocally assign the stabbing tool to the stab wound because the bone shard, which was removed neurosurgically to relieve intracranial pressure, was presented at autopsy, and it exactly matched the instrument of the crime. The length of the intracranial puncture canal could also be reconstructed in this way. A potential murder weapon was found at the scene immediately after the event, but was not available at autopsy due to police investigations. However, at trial about one year later, there was the opportunity to perform a reproducible demonstration of the forensic reconstruction findings in foro, even without postmortem radiological findings.

Fatal penetrating skull stabs are an absolute rarity. This applies to accidents, homicides and suicides [1,2,3,4]. Accordingly, scientific reports on both the injury morphology and the force required to penetrate a human skull bone are sparse. In addition to skin, fatty tissue and muscles, porcine ribs can also be easily cut by adults using a knife with moderate effort (Energy approx. 1200 N, Force 11–16 J) [5–6]. Bony structures show the greatest resistance to penetrating piercing tools of any human tissue, which is not surprising [7–8]. It was obvious that the stab in the presented case was carried out very powerful, active, intentional and most likely directed downwards. The small fractures on the outside of the skull next to the penetrating bony injury were possibly attributed to the impact of the knife handle but could have been also just the result of the stab without additional blunt force. Although, it was not possible to make reliable statements about the amount of force required, an accident could be excluded.