Pathologists usually only request a screening for natural toxic substances if plant material has been observed during autopsy or if there exists a hint in the police investigation file. This situation is aggravated by the fact that most toxins are not covered by typical immunoassays and gas chromatography–mass spectrometry (GC–MS) profiling systems. In addition, only a few forensic toxicological libraries based on liquid chromatography coupled to high-resolution tandem mass spectrometry (LC–HRMS/MS) exist. In the following case, femoral blood and urine were applied to systematic toxicological analysis (STA). However, the concentrations determined in blood did not lead to death. Consequently, a liquid chromatography high-resolution tandem mass spectrometry (LC–HRMS/MS) screening approach was applied. Aconitine was quantitated in all specimens taken during autopsy and urine and bile fluid screened for aconitine metabolites. Aconitine, jesaconitine, hypaconitine, and mesaconitine were found in the root piece collected from the duodenum. Apart from aconitine, no other alkaloids were detected in the urine or in the femoral blood sample. The highest concentrations of aconitine were found in gastric content (55.2 μg/mL), bile fluid (11.7 μg/mL), and liver (9.14 μg/g), and least in femoral blood (0.15 μg/mL) and cerebrospinal fluid (0.07 μg/mL). The liver/peripheral blood ratio amounted to 61 L/kg and indicated that aconitine undergoes postmortem redistribution. During our metabolism investigation, we found 3-dehydrogen-aconitine in the urine and bile fluid sample and N
-deethyl-aconitine only in the bile fluid sample. If the routine GC–MS screening approach does not come up with a toxin, then LC–HRMS/MS profiling could represent the method of choice. In this case aconitine was identified. The concentrations determined were compared to those reported in literature and clearly indicate that the deceased died due to an aconitine overdose.