Forensic Epigenetics for Casework: A Systematic Scoping Review of DNA Methylation-Centred Applications and Validation Evidence

Background/Objectives: Forensic epigenetics complements DNA profiling by informing donor age and trace origin, but technical promise does not establish casework validity. We mapped applications and validation evidence. Methods: Scopus, PubMed/MEDLINE and Web of Science were searched through 15 June 2026. Empirical reports were assigned a dominant application and an author-defined C1–C5 evidence category (not a readiness score). Results: Of 596 assessed full texts, 338 entered the evidence map (322 empirical studies and 16 contextual records). Among studies, 312/322 (96.9%) fell within C1–C3, 10 were C4 and none met the C5 definition of documented routine implementation in the indexed and retrievable corpus. C4 records advanced evaluation designs, which may reveal unsuccessful transfer or unresolved bias rather than acceptable casework performance. Age estimation (177 studies) and body-fluid/tissue identification (92) accounted for all C4 evidence. Of 272 identifiable methylation workflows, chemical conversion predominated; 23 studies were non-methylation, 26 reused methylation data without a new assay and one workflow remained unresolved. Conclusions: Published evidence is substantial but heterogeneous; internal performance cannot substitute for independent validation, inter-laboratory reproducibility, calibrated uncertainty, laboratory-specific procedures, controlled reporting and proportionate governance. Study-level counts do not quantify the proportion of distinct validated methods or establish absence of unindexed operational use.