The investigation remains ongoing.
The soldiers were part of a 2,200-member Marine combat unit that rotates deployment on three Navy amphibious vessels, reports said.
On the day of the accident, the team had completed training on San Clemente Island and was returning to the USS Somerset when the craft began taking on water with 15 Marines and one sailor on board.
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Six Marines were rescued from the water, but seven others and the sailor were trapped inside and went down with the vessel. Another Marine died from his injuries after reaching shore.
A search team recovered the dead a week later from the ocean floor, 385 feet down. They ranged in age from 18 to 23, reports said.
The nine victims were identified as Pfc. Bryan J. Baltierra, Pfc. Evan A. Bath, Pfc. Jack-Ryan Ostrovsky, Lance Cpl. Marco A. Barranco, Lance Cpl. Guillermo S. Perez, Lance Cpl. Chase D. Sweetwood, Cpl. Wesley A. Rodd, Cpl. Cesar A. Villanueva and Navy Hospital Corpsman 3rd Class Christopher Gnem.
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Regner was the commanding officer of the Battalion Landing Team, 1st Battalion, 4th Marine Regiment, 15th Marine Expeditionary Unit, according to the Marine Corps statement.
While details about the specific vehicle involved in the accident are not yet known, such vehicles have been in service since the early 1970s, though they have been updated and rehabilitated in the years since. Replacing the vehicles with expeditionary fighting vehicles was a top priority for the Marines, but a budget crunch in 2011 led to scrapping those plans.
A planned replacement for the assault amphibious vehicle is still in development.
Information provided by Tribune News Service was used to supplement this report.