Determining Manner, Mechanism, and Cause of Death

For forensic purposes, it may be important to determine if the lesions were inflicted postmortem or antemortem, if they were lethal or not, and the age of lesions. This information may be determined at necropsy and histopathological exam. If the lesion was inflicted antemortem, hemorrhage will occur and be detected by gross and/or microscopic examination and will extend through several tissue planes. Postmortem hemorrhage is generally distinguished microscopically by confinement of the blood to a single fascial plane; however, if the body is putrefied, such determination is difficult (Betz & Eisenmenger, 1996; Sauvageau & Racette, 2008).

The cause of death should be defined as sharp injury with an indication of the topographical regionfs) affected, and it depends on the site and vessels/organs involved. The most frequent cause of death is hypovolemic shock resulting from hemorrhage, which occurs when major blood vessels are affected (see Table 8.2). Stabbing in the thorax or abdomen may cause internal bleeding (Dettmeyer et al., 2014). When the limbs, head, or neck are affected, there may be a large amount of blood at the crime scene. The mechanism of death depends on the site and vessels/organs involved, but the most frequent cause of death is hypovolemic shock resulting from hemorrhage, which occurs when major blood vessels are severed (Di Maio & Di Maio, 2001; Dettmeyer et al., 2014). Lesions in the thorax and neck are most likely to be fatal; when the trachea is affected, the mechanism of death may be asphyxiation due to the aspiration of blood. The manner of death should be determined in conjunction with crime scene data, that is, bloodstain patterns. Histopathological analysis may be useful in cases of multiple wounds, because it may be difficult to determine the timing of wounds relative to death based only on their gross appearance. The amount of hemorrhage may not be a reliable indicator because unless the circulation has ceased for some time, some bleeding is likely to occur from injuries that are inflicted near death or shortly thereafter (Illinois Coroners and Medical Examiners Association, 2007).

Table 8.2 Sharp force trauma: Cause, mechanism, and manner of death considerations

^a Munro & Munro (2008); Schlesinger et al. (2014).

In cases of sharp force trauma to the lung, liver, spleen, or kidney, bleeding in the internal cavities is also likely to occur for several hours after death until all of the blood from the area has drained (Di Maio & Di Maio, 2001; Dettmeyer et al., 2014).

Late complications due to sharp force trauma include undetected bleeding in internal viscera, including lung, liver, spleen, or kidney, that may occur for several hours after death. Infections may also occur in days or weeks after sharp injuries have occurred in cases of non-lethal lesions. Sharp force injuries in intestines may cause peritonitis. Other causes may be from intentional wounds, such as torture or aggression and undiagnosed accidental stab wounds, such as in vehicular accidents (Byard et al., 2012).

Crime Scene Findings

Whenever possible, in cases of violent or suspicious deaths of animals, crime scene investigation is highly recommended. In cases of sharp force injuries, bloodstain pattern analysis (BPA) may give information about angle and distance of the blood spatter (de Bruin et al., 2011; Attinger et al., 2013). Its shape and pattern may indicate its source or point of origin. Blood spatter indicates the direction of the origin of the bleeding. All length and width spatter measures should be taken, in addition to the distance of the drops from their point of origin. BPA may provide information about the type of weapon used, the position of the weapon(s), the objects, the victim and the perpetrator, the movement of the individuals present at the crime scene, and an estimation of the number of stabs, blows, or shots. A castoff pattern may be found in cases of sharp force trauma, where the blood is projected from an object or other bloody source. The information provided by these parameters may assist in the reconstruction of the events that culminated in death. BPA should be paired with necropsy findings and molecular biology. The DNA of the blood may be considered to determine whether the blood is from the animal or from the perpetrator, who may have received injuries during the stabbing or shooting. The reconstruction of events may be interpreted based on this information. The examination of the crime scene may contribute to the elucidation of the cause and manner of death, as well as the interpretation of particular postmortem findings (Peschel et al., 2011; Osborne et al., 2016).