Rear Admiral Jeffries began his naval career in 1976 through the Armed Forces Health Professional's Scholarship Program and earned his BA from Coe College in Cedar Rapids, Iowa. He completed graduate studies at the University of Colorado in secondary education, earning a State of Colorado teaching certificate. He graduated from the College of Osteopathic Medicine and Surgery in Des Moines, Iowa in 1979.
Jeffries completed an internship and Family Medicine residency at Naval Hospital Pensacola, Fla. in 1982 and immediately attained board certification from the American Board of Family Practice. His first staff assignment was to Branch Naval Hospital Twenty-nine Palms, Calif., where he received appointments as head, Family Practice Department, acting director Clinical Services, and chief, Medical Staff.
In August 1984 Jeffries was transferred to the Department of Family Medicine at Naval Hospital Camp Pendleton, serving as staff Family Physician, Residency Faculty and Clinic director. In 1986 he was promoted to director, Residency Training where he attained board certification in Family Practice from the American Osteopathic Board of General Practice and Fellow, American Academy of Family Physicians. Jeffries is a member of the American Academy of Family Physicians, Association of Military Osteopathic Physicians and Surgeons (Past President), Uniformed Services Academy of Family Physicians, American Osteopathic Association, and the Association of Military Surgeons of the United States.
In August of 1990 he served in Operation Desert Shield as Artillery Regimental surgeon, 11th Marines. While in theater he was deputy then acting division surgeon. A year later he was assigned to the 1st Marine Division as division surgeon. In December 1992 he was appointed Marine Forces Central Command and I Marine Expeditionary Force (Forward) force surgeon for Operation Restore Hope, Somalia.
In the summer of 1993 Jeffries was re-assigned to Naval Hospital Camp Pendleton as Family Practice Department head and Residency Program director. In 1996 he was appointed chairman, Executive Committee of the Medical Staff and completed his tour as director, Medical Services. In October 1998 he reported to Marine Forces Pacific, Camp Smith, Hawaii, as the force surgeon. In April 2000 he assumed duties as the deputy commander for Clinical Services at Tripler Army Medical Center until April 2003 when he assumed command at Naval Hospital Camp Pendleton. In August 2005 Jeffries reported to the Bureau of Medicine and Surgery as the deputy chief for Future Plans and Strategies. Soon after his arrival, Jeffries was deployed as the JFMCC surgeon in support of Hurricane Katrina relief efforts. From November 2005 to July 2007 Jeffries was medical officer to the Marine Corps. He then assumed command of National Naval Medical Center and Regional Commander Navy Medicine National Capitol Area in Bethesda. In August 2008 he returned to Headquarters U.S. Marine Corps where he is currently assigned.
Jeffries’ personal decorations include the Legion of Merit with four Gold Stars, Bronze Star, Joint Meritorious Service Medal, Meritorious Service Medal with one Gold Star, Combat Action Award, Joint Meritorious Unit Award, Navy Unit Commendation, Meritorious Unit Commendation, Bronze Star, Army Order of Military Medical Merit, and Artillery Order of Saint Barbara.