THE ROLE OF EPIGENETIC BIOMARKERS AND DNA METHYLATION ANALYSIS IN AGE ESTIMATION AND TISSUE IDENTIFICATION FOR MODERN FORENSIC INVESTIGATIONS

Abstract

DNA methylation has emerged as an important epigenetic biomarker for forensic investigations because it can provide biological information beyond conventional DNA profiling. This study examined the role of CpG methylation markers in forensic age estimation and tissue-identification interpretation using a secondary data-based computational design. A publicly available methylation dataset, GSE207605_GSE40279.csv.gz, containing 656 samples and 2,374 CpG markers with chronological ages ranging from 19 to 101 years, was analyzed. Data preprocessing confirmed complete methylation and age information, with no missing values. CpG markers were ranked according to their association with chronological age, and the strongest age-associated markers were used to develop a ridge regression-based age-estimation model. Model performance was evaluated using cross-validation and compared with a mean-age baseline model. The methylation-based model substantially outperformed the baseline, reducing mean absolute error from 11.92 years to 4.06 years and achieving an R² value of 0.862. These findings demonstrated that selected CpG methylation markers carried strong age-predictive information and supported their forensic value for donor age estimation. Direct tissue-identification modeling was not performed because tissue-origin labels were unavailable; however, tissue-specific methylation was discussed as a complementary forensic application. Overall, DNA methylation analysis showed strong potential for enhancing forensic biological inference through age estimation and tissue-origin interpretation.