Mushroom-related intoxications pose a distinctive challenge for forensic medicine because early manifestations are non-specific, latency may be prolonged, and co-exposures can obscure the mechanism of death. This narrative review summarizes key toxic and psychoactive fungi and their principal compounds, spanning organ-toxic syndromes (amatoxins, orellanine) and functional neuropsychiatric intoxications—acute, predominantly functional effects causing impairment rather than organ failure (psilocybin/psilocin, ibotenic acid/muscimol). We propose an integrated diagnostic workflow combining exposure history, biochemical markers of organ injury, mycological assessment, and confirmatory toxicology. Particular emphasis is placed on postmortem interpretation: toxin instability and biotransformation, conjugation, matrix effects, postmortem redistribution (central vs. femoral blood), and postmortem fungal colonization that may alter analyte profiles or generate misleading metabolites. Because robust lethality thresholds are unavailable for most mushroom toxins, conclusions should rely on a multi-source synthesis of scene information, autopsy/histopathology, and time-dependent matrix selection (urine, gastric contents/vomitus, bile, and selected tissues; kidney for late orellanine confirmation). We review current screening and confirmatory methods—ELISA; LC-MS/MS, LC-HRMS/MS, GC-MS—and highlight pre-analytical requirements (rapid sampling, cold storage) to reduce false negatives. Finally, we discuss emerging directions such as point-of-care tests, portable mass spectrometry, and DNA barcoding for species identification. Keywords: fungi; toxic fungi; psychoactive fungi; toxicology; forensic toxicology; forensic medicine