Forensic investigation of unexpected multi-drug overdoses: A case series suggesting potential homicidal poisoning

Homicidal poisoning involving multiple prescription medications presents significant diagnostic challenges, particularly in determining intent. We present a case series of two unexpected deaths within the same social community, both linked to the same suspect. In Case 1, a 49-year-old woman found unresponsive was referred for forensic autopsy as a suspicious death. Although initial findings were non-specific, postmortem toxicological analysis revealed fatal multi-drug poisoning involving tramadol, diltiazem, and metoprolol. The investigation of Case 1 subsequently raised suspicion regarding Case 2, a 50-year-old woman originally certified as a natural death and buried without an autopsy. Following exhumation, toxicological evaluation of decomposed samples demonstrated exposure to tramadol, diltiazem, and metoprolol. Postmortem toxicological analysis was conducted at the Chemistry Specialization Department's ISO/IEC 17025-accredited laboratory, using advanced analytical techniques such as LC-MS/MS, liquid chromatography-time-of-flight mass spectrometry (LC-TOF-MS), and GC-MS. Review of both victims' medical histories revealed no records of prescriptions for tramadol, diltiazem, or metoprolol. The presence of a common suspect, absence of relevant medical prescriptions for either victim, and associated investigative findings supported third-party involvement, making homicidal poisoning highly probable, although the possibility of voluntary ingestion within a socially influenced context was also considered. This case series highlights the critical role of comprehensive toxicological analysis and multidisciplinary forensic evaluation in the reclassification of unexpected deaths. It underscores the importance of meticulous investigation to identify potential homicidal poisonings that may otherwise be misclassified as natural or undetermined.