Koji Yamaguchi is an Associate Professor in the Department of Forensic Medicine, School of Medicine, International University of Health and Welfare, Japan. His research interests include LC-MS/MS analysis of drugs and toxic compounds in postmortem specimens, drug metabolite analysis in autopsy samples, and the development of derivatization methods for LC-MS analysis. Dr. Yamaguchi has 26 years of experience in LC-MS/MS analysis in police forensic laboratories and forensic medicine, with expertise in forensic toxicology and postmortem drug analysis.