Homicide-suicide in three regions of the Czech Republic: A retrospective autopsy-based study (1998-2023).

Homicide-suicide (H-S) is a rare but highly consequential form of fatal violence in which one or more homicides are followed by the perpetrator's suicide. Although H-S has been reported in several countries, systematic forensic data from the Czech Republic remain limited. This retrospective autopsy-based study analyzed H-S cases recorded in three regions of the eastern Czech Republic between 1998 and 2023 to characterize their epidemiological, medicolegal, and toxicological features. Variables were extracted from autopsy reports, police findings, and toxicological reports. Cases were classified according to the typology proposed by Marzuk et al. A total of 39 H-S incidents involving 108 decedents were identified, corresponding to a mean annual incidence of 0.06 incidents per 100,000 inhabitants. Intimate partner H-S was the most frequent subtype (46.2%), followed by familial (33.3%) and extrafamilial (20.5%) incidents. Perpetrators were predominantly male (92.3%); female perpetrators were younger and occurred exclusively in filicide-suicide cases. Firearms were the leading lethal mechanism, and method concordance between homicide and suicide was observed in 61.5% of incidents. Ethanol was detected in 11 of 39 perpetrators (28.2%) and in 9 of 69 victims (13.0%). Jealousy or revenge was the most commonly recorded motive in intimate partner and extrafamilial incidents, whereas altruistic motives were more prominent in familial cases. These findings are consistent with international patterns and indicate that H-S prevention requires multidisciplinary strategies focused on domestic violence escalation, mental health crisis intervention, firearm access assessment, and substance use as a contextual factor rather than a demonstrated causal factor.