CAMP FOSTER, Okinawa — The Marine Corps on Thursday released the identity of an Okinawa Marine who died earlier this week after emergency responders were called to his off-base home.

Staff Sgt. Donald B. Landgraf, 35, of St. Charles, Ill., was pronounced dead at the Camp Lester Navy hospital Tuesday. The cause of death remains under investigation, the service said. He was assigned to Marine Wing Support Squadron 172 of the 1st Marine Aircraft Wing on Okinawa.

Landgraf, who was married with three children, was about to begin warrant officer’s training and had built an “extremely successful” military career that included serving in Iraq and Afghanistan, according to a statement from Maj. Briton Breck, squadron executive officer.

“Staff Sgt. Landgraf was in excellent mental and physical health as he was preparing to attend the Warrant Officer Basic Course in January, so his passing at such an early age is tragic and shocking,” Breck said.