Retired agent Dr. Joseph Dizinno, DDS. served in the FBI for 22 years. Prior to joining the FBI, Dr. DiZinno, who received a Doctor of Dental Surgery Degree from The Ohio State University in Columbus, Ohio, owned and operated a family dental practice. He was initially assigned to the Washington Field Office where he investigated reactive crimes. After three years in the field, he was promoted and transferred to the FBI Laboratory where he began to specialize in the examination of hairs and fibers. Dr. DiZinno served as a critical investigative resource on many high-profile cases including dental and DNA identification at the Branch Davidian Cult fire, kidnappings, and major extortion cases. In this episode of FBI Retired Case File Review, Dr. DiZinno reviews the functions of FBI Laboratory and the investigation of the tragic murders of Joann Katrinak and her baby Alex where mitochondrial DNA analysis was first applied to forensic casework. He was part of the research team that developed and validated forensic mitochondrial DNA analysis capability which enabled the FBI to obtain a DNA profile from evidence containing small or degraded quantities of DNA from hair, bone, teeth, and bodily fluids. Dr. DiZinno ended his Bureau career as the Director of the FBI Laboratory where he led more than 550 FBI Laboratory personnel, providing forensic examinations, technical support, expert witness testimony, and training to federal, state, and local law enforcement agencies and responding to events all around the world. Currently, Dr, DiZinno is a faculty member at George Mason University in Fairfax, Virginia where he teaches forensic science to undergraduate and graduate level students in the Forensic Science Program.