Aging is a natural and gradual process in human life, and is influenced by heredity, environment, lifestyle, and disease. DNA methylation varies with age, and the ability to predict the age of donor using DNA from evidence materials at a crime scene is a considerable value in forensic investigations. Recently, many studies have reported several age prediction models based on DNA methylation from various tissues and body fluids. Those models seem to be very promising because of their high prediction accuracies. In this review, the changes of age-associated DNA methylation and the age prediction models for various tissues and body fluids were examined, and then the applicability of the DNA methylation-based age prediction method to the forensic investigations was discussed. This will improve our understandings about DNA methylation markers and their potential to be used as biomarkers in the forensic field, as well as in the clinical field.