Self-inflicted hammer blows to the head-Literature and case review.

Self-inflicted hammer blows to the head are rare occurrences in forensic medicine, particularly when they are lethal. In the majority of cases, no distinction between self-inflicted injury versus assault has to be made. However, when assault is claimed and such distinction is required, the task may be challenging. We report a case concerning a 32-year-old psychotic woman, who had suffered multiple lacerations of the scalp and survived after claiming she had been assaulted with a hammer by an acquaintance. A clinical forensic examination was performed as well as the inspection of the scene of the incident for bloodstain pattern analysis. In summary, findings were inconsistent with assault and the injuries were determined to be self-inflicted. In addition, a retrospective analysis of our own autopsy records as well as a search in scientific literature and the internet for self-inflicted hammer blows to the head was conducted. For the majority of published cases a positive psychiatric history is reported. While published cases were few, potentially characteristic properties of self-inflicted hammer blows to the head were identified. For example, self-inflicted hammer blows may be identified by the absence of defensive wounds, injuries to the face and extracranial injuries and the finding that they are most commonly distributed in an area usually covered by a 'zuchetto' skull cap.

Prism (II): 127 cooling dummy experiments.

The Prism method for temperature based time since death estimation has been demonstrated as a proof of principle in 2021. Now it was validated experimentally. 10 cooling dummies (physical weights from 5.9 kg to 26.9 kg) were fabricated and fitted with temperature probes. A total of 127 dummy cooling experiments were conducted (total cooling time 2082 h, average cooling time 24.6 h) for both regular and elevated starting temperatures, covering ambient temperatures between - 14.0 °C and + 24.0 °C and for different cooling conditions. Cooling data was recorded, then cropped, smoothed, fed into the Prism workflow, and analyzed using dedicated scripts written in the Python programming language. Calculations did not take any additional information into account. No correction factors were needed. General Prism cooling weight curves were confirmed (false ambient temperature and elevated rectal temperature at the time of death). Sub-zero ambient temperature generated unexpectedly large cooling weights. Time since death estimation errors were - 0.29 h ± 5.24 h (whole course of cooling, all experiments) and were typically smaller in earlier stages of cooling. Prism performed relatively well, where conventional temperature based death time estimation struggles. In the future it may potentially be adapted to known conditions. Our results indicate that Prism's cooling weight might serve as a highly individual, case-based data-driven umbrella parameter, replacing (subjectively) estimated parameters.

Prism - A novel approach to dead body cooling and its parameters.

In temperature based death time estimation, the mathematical description by Marshall and Hoare is combined with the parameters defined and additional correction factors introduced by Henssge in the Nomogram method (summarized as MHH). Parameters and correction factors however leave room for subjectivity and disagreement. Elevation of rectal temperature at the time of death has been acknowledged as problematic for death time estimation in several studies, but has neither been solved nor systematically integrated into death time estimation methodology. Ambient temperature, when non-constant and/or unknown, may introduce additional errors. Further problems may arise if the fundamental relationship between torso dimensions and total body weight is not comparable to Henssge's dummy cooling model. In this study we present a novel methodological approach to temperature based death time estimation, in which relevant parameters for calculations may be evaluated, corrected and generated using brute-force calculations. Consistency of death time over the course of cooling is used as brute-force target. The calculations produce momentary cooling weights, which are graphed over time. Cooling weight graphs can be analyzed to draw conclusions related to different parameters. The method was used on artificial ideal cooling data which was generated according to MHH for known parameters. Correctness of assumed parameters was confirmed by a linear horizontal path of the cooling weight graph. However, controlled false value input resulted in characteristic graph variations. Elevated rectal temperature at the time of death was detectable from the curve shape until hours after cooling below regular temperature at death. False high and false low ambient temperature produced positive and negative curve slopes. Overall, the method acts much like a prism which breaks up light into its elemental colors. It holds potential for application both in scientific settings and practical case work.

Hammer blows to the head.

Hammer blows cause serious, often fatal injuries, especially when massive blunt violence is targeted at the head region. The evaluation of the injury potential depends not only on the body region hit, but also on the characteristics of the hammer as a weapon and on the physical characteristics of the attacker. This study aimed at elucidating the dependency between the physical constitution of a perpetrator and the intensity of hammer blows, thus to verify or refute this seemingly obvious interrelation sometimes expressed in the saying that a "strong hand strikes harder". For this purpose, 113 volunteers of different ages and sexes took part in different experimental settings. While, as expected, clear differences between male and female were detectable in the striking power of single and multiple strokes, there were no age or sex differences with regard to the maximum number of strokes per time unit. Strength differences in slamming with a hammer between men and women exceeded expectations in this study. Using the fracture forces as described by Sharkey et al. in an exemplary manner, one can expect a fracture of the skull in 9 out of 10 cases with a 300 g hammer by men for intensively executed single strokes, whereas this was only the case for approx. 2/10 women in this study. The maximum circumference of the upper arm and the width of the shoulder girdle correlate significantly with the achievable impact forces of individual hammer blows in both sexes. A simple measurement of the hand force with a manometer using the regression formula y [kN] = 0.144 × manual grip force -1.08 can be used as a rough estimation parameter for the theoretically achievable impact force. If one strikes repeatedly with the same hammer for 1 min, the magnitude of a single strike decreases continuously from 4.5 kN to 2.6 kN on average. If a 1500 g hammer is used instead of a 300 g hammer, one does not get the fivefold impact force you might expect at first sight, but only on the order of twice the impact force, about 14 kN on average. The results prove the importance of physical experiments, whose results can help to better interpret the magnitude and effects of hammer blows as a form of potentially life-threatening violence.

Minimum time since death when the body has either reached or closely approximated equilibrium with ambient temperature.

In temperature based death time estimation the construction of a death time interval using the conventional Nomogram method (NM) is not permissible for bodies in which rectal temperature (Tr) has reached or closely approximated equilibrium with ambient temperature (Ta). We provide a logic approach to compute a minimum time since death with high probability. We also provide a simple graphical solution to be used at the crime scene for preliminary estimation. Special attention is advised in regards to cases with Ta>23°C as well as borderline cases. Proof by induction, application to test cases and one example of use are presented.