How Should the Time Interval be Defined in Homicide-Suicide Cases?

Purpose: Homicide−suicide behavior ordinarily refers to people who attempt to kill other people then themselves within a week. However, some offenders may have suicide behaviors before or almost simultaneously with homicide acts. The present study aimed to examine the time interval involved in homicide−suicide behavior. Methods Murderers who have attempted suicide or individuals who have attempted murder and suicide are regarded as homicide−suicide offenders. We searched Chinese court documents to identify these individuals. We classified them into five groups: those who attempted suicide more than 24 hours before (T1); within 24 hours before (T2); almost simultaneously (T3); within 24 hours after (T4, reference group); and more than 24 hours after (T5) homicide acts. We used multinomial logistic regressions to compare demographics, methods of homicide and suicide, and risk factors among the five groups. Results A total of 987 offenders were included (T1, 62; T2, 111; T3, 103; T4, 688; T5, 23). T1 (OR, 2.94; p  < 0.01), T2 (OR, 1.89; p  < 0.05), and T3 (OR, 3.73; p  < 0.01) were more likely to be female than T4; T1 (33.9% vs 19.4%) and T5 (65.2% vs 30.4%) were more likely to attack extra-family members than intimate partners; and T1 were more likely to have psychiatric illnesses than T4 (OR, 9.33; p  < 0.001). Conclusions If the tendency of attacking intimate partners was set to be the primary inclusion standard of HS, only cases that involved less than one-day intervals between homicidal and suicidal acts could be regarded as homicide−suicide.