Postmortem toxicological investigations in cases with an extended postmortem interval and advanced decomposition

Postmortem (PM) toxicological analysis and interpretation are complicated by PM redistribution, degradation and/or formation. Most existing knowledge on PM compound concentration changes is based on animal and human studies with a PM interval (PMI) up to a week. Consequently, there is limited knowledge of how concentrations change in cases with an extended PMI or advanced decomposition. In this narrative review we provide an overview of existing literature describing toxicological measurements in human tissue and bodily fluids with a PMI of 168 h (seven days) or more. After a literature search, the information on PMI, matrix, compound and decomposition was collected from 56 selected publications, the majority of which were case reports or case series. An overview is provided of investigated matrices and detected compounds across five PMI groups. Localized and confined bodily fluids, such as femoral blood and cardiac blood and vitreous humor, have been sampled up to four weeks PM, but are usually only available for several days PM. Collection and analysis of soft and hard tissues were described, identifying 147 different compounds in cases with PMI's up to ten years and beyond. Although the number of false negative results in these publications is unknown, these findings are in support of qualitative investigation of drug exposure in alternative matrices after an extended PMI. However, one should refrain from drawing conclusions regarding perimortem effects based on quantitative results. Toxicological findings should be considered supportive of those from pathological and crime scene investigations and interpreted as part of the death investigation.