A U.S. Marine was found dead Monday morning by the Japan Coast Guard off the coast of Camp Schwab in Okinawa, according to Stars and Stripes.

The Marine, who has not been identified, was assigned to Marine Corps Installations Pacific.

The cause of death has not been released.

The Naval Criminal Investigative Service is investigating the death.

“The thoughts and prayers of the entire command are with the family, friends and co-workers of the deceased Marine,” a statement from the Marines said. “We extend our deepest gratitude to our Japan Coast Guard partners for their immediate professional assistance in searching for and locating our deceased Marine.”