Evidential convergence in the forensic attribution of death due to hydrogen sulfide intoxication: a systematic review protocol.

BACKGROUND: Attribution of death to hydrogen sulfide (H2S) is challenging because autopsy findings are often nonspecific, postmortem toxicology is vulnerable to analytical and decomposition-related uncertainty, and scene investigation varies in completeness. A systematic appraisal of how these domains support or weaken published causal conclusions is needed. METHODS: This protocol specifies a systematic review with structured narrative synthesis of peer-reviewed human fatality reports in which H2S exposure is suspected or attributed, together with relevant human postmortem comparator studies. MEDLINE via PubMed, Embase, Scopus, Web of Science, and the Cochrane Library will be searched for studies published from 1 January 2007 onward. English-language eligibility will be assessed during screening. Two reviewers will independently select studies, extract prespecified case-level data, and undertake design-specific JBI critical appraisal without total scores. A rule-based matrix will distinguish interpretable exposure evidence, nonspecific compatibility, unresolved discordance, and missing information. Original authors' conclusions will be recorded separately from reviewers' assessments. Recurrence will be summarized descriptively; discriminatory claims will require appropriate within-study comparators and an independently established attribution basis. Formal GRADE ratings and diagnostic-accuracy pooling are not planned. DISCUSSION: The completed review will examine the documented basis and limitations of forensic attribution, including cases with absent or inconclusive toxicology. The proposed convergence profiles are descriptive constructs, not validated diagnostic thresholds or probabilities of causation. Study and case counts, the PRISMA 2020 flow diagram, and synthesis findings will be reported in the completed review; this protocol contains no review results. REVIEW REGISTRATION: PROSPERO CRD420261324108.