CAMP PENDLETON, Calif.—A Marine Corps panel convenes Tuesday to decide if an officer should be discharged over the sinking of an amphibious assault vehicle in the ocean off Southern California that killed nine service members. Lt. Col. Michael J. Regner was relieved of command of the landing team of the 1st Battalion, 4th Marine Regiment, 15th Marine Expeditionary Unit, shortly after the mishap off the coast of San Clemente Island on July 30, 2020. A Marine Corps statement at the time said his removal was based on “a substantial amount of information and data” and cited a loss of trust. If the Board of Inquiry, composed of three officers, determines Regner should be discharged, he could potentially lose retirement benefits and privileges. The hearing is expected to run up to four days. A Marine Corps investigation found that inadequate training, shabby maintenance and poor judgment by leaders led to the …