An unusual case of serial poisoning of family members

The authors present an unusual criminal case of delusionally motivated, serial intrafamilial killings by a psychotic offender. Because the offender retained instrumental rationality and killed his victims by stealth, viz. surreptitious poisoning, the killing of his first victims went undetected. Persecutory delusions of being poisoned not uncommonly result in defensive violence, whereas in this case, religious delusions resulted in the mentally ill person killing others by poisoning them. Here, the psychotic offender killed his victims by means of poisoning based upon motivation driven by religious delusions. This case illustrates the importance of index of suspicion and appropriate investigation of mysterious deaths, and careful forensic psychiatric assessment to distinguish delusional versus extreme overvalued belief‐motivated killings in addressing the insanity defense.